#!/usr/bin/env python3
"""
Generate a journal-style PDF on Nanomedicine in Veterinary Drug Delivery,
mimicking the format of the AJVR article (two-column layout, academic style).
"""

from reportlab.lib.pagesizes import letter
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import inch, cm
from reportlab.lib.colors import HexColor, black, white, Color
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, HRFlowable, Table, TableStyle,
    KeepTogether, PageBreak, FrameBreak
)
from reportlab.platypus.frames import Frame
from reportlab.platypus.doctemplate import PageTemplate, BaseDocTemplate
from reportlab.lib.enums import TA_LEFT, TA_CENTER, TA_JUSTIFY, TA_RIGHT
from reportlab.platypus import BaseDocTemplate, PageTemplate
from reportlab.lib import colors

# --- Color palette matching the original journal ---
HEADER_BLUE    = HexColor('#003366')   # dark navy header bar
ACCENT_BLUE    = HexColor('#1a5276')   # section headings
LIGHT_BLUE     = HexColor('#d6eaf8')   # abstract background tint
RULE_COLOR     = HexColor('#2980b9')   # horizontal rules
BODY_BLACK     = HexColor('#1a1a1a')   # body text
JOURNAL_RED    = HexColor('#c0392b')   # journal name accent (optional)
MEDIUM_BLUE    = HexColor('#2471a3')

PAGE_W, PAGE_H = letter  # 8.5 x 11 inches

# --------------------------------------------------------
# Custom DocTemplate with two-column layout + header/footer
# --------------------------------------------------------
class TwoColumnDoc(BaseDocTemplate):
    def __init__(self, filename, **kwargs):
        BaseDocTemplate.__init__(self, filename, **kwargs)
        self.addPageTemplates(self._build_templates())

    def _build_templates(self):
        pw, ph = PAGE_W, PAGE_H
        margin_t = 0.75 * inch
        margin_b = 0.85 * inch
        margin_l = 0.6 * inch
        margin_r = 0.6 * inch
        gutter   = 0.25 * inch

        col_w = (pw - margin_l - margin_r - gutter) / 2
        col_h = ph - margin_t - margin_b

        # --- First page (full-width title + two-col body) ---
        title_h     = 2.65 * inch     # header banner
        abstract_h  = 2.1  * inch    # abstract box
        body_top    = margin_t + title_h + abstract_h + 0.1 * inch
        body_h      = ph - body_top - margin_b

        left_col_p1 = Frame(
            margin_l, margin_b, col_w, body_h,
            leftPadding=0, rightPadding=0, topPadding=0, bottomPadding=0,
            showBoundary=0, id='p1_left'
        )
        right_col_p1 = Frame(
            margin_l + col_w + gutter, margin_b, col_w, body_h,
            leftPadding=0, rightPadding=0, topPadding=0, bottomPadding=0,
            showBoundary=0, id='p1_right'
        )

        # Full-width frame on first page for title + abstract
        header_frame = Frame(
            margin_l, ph - margin_t - title_h,
            pw - margin_l - margin_r, title_h,
            leftPadding=0, rightPadding=0, topPadding=0, bottomPadding=0,
            showBoundary=0, id='p1_header'
        )
        abstract_frame = Frame(
            margin_l, ph - margin_t - title_h - abstract_h,
            pw - margin_l - margin_r, abstract_h,
            leftPadding=0, rightPadding=6, topPadding=0, bottomPadding=0,
            showBoundary=0, id='p1_abstract'
        )

        first_page = PageTemplate(
            id='FirstPage',
            frames=[header_frame, abstract_frame, left_col_p1, right_col_p1],
            onPage=self._first_page_decorations,
        )

        # --- Subsequent pages (full two-column) ---
        left_col = Frame(
            margin_l, margin_b, col_w, col_h,
            leftPadding=0, rightPadding=0, topPadding=0, bottomPadding=0,
            showBoundary=0, id='left'
        )
        right_col = Frame(
            margin_l + col_w + gutter, margin_b, col_w, col_h,
            leftPadding=0, rightPadding=0, topPadding=0, bottomPadding=0,
            showBoundary=0, id='right'
        )
        later_pages = PageTemplate(
            id='LaterPages',
            frames=[left_col, right_col],
            onPage=self._later_page_decorations,
        )

        return [first_page, later_pages]

    # ---- decorations ----
    def _draw_footer(self, canvas, doc, page_num):
        canvas.saveState()
        canvas.setFillColor(BODY_BLACK)
        canvas.setFont('Helvetica', 7)
        footer_y = 0.5 * inch
        canvas.drawString(0.6 * inch, footer_y,
            'American Journal of Veterinary Research  |  Nanomedicine in Veterinary Drug Delivery')
        page_str = str(page_num)
        canvas.drawRightString(PAGE_W - 0.6 * inch, footer_y, page_str)
        canvas.setStrokeColor(RULE_COLOR)
        canvas.setLineWidth(0.5)
        canvas.line(0.6 * inch, footer_y + 9, PAGE_W - 0.6 * inch, footer_y + 9)
        canvas.restoreState()

    def _first_page_decorations(self, canvas, doc):
        canvas.saveState()
        pw, ph = PAGE_W, PAGE_H
        margin_t = 0.75 * inch
        margin_l = 0.6 * inch
        margin_r = 0.6 * inch
        title_h  = 2.65 * inch

        # Top header bar
        canvas.setFillColor(HEADER_BLUE)
        canvas.rect(margin_l, ph - margin_t - 0.32 * inch,
                    pw - margin_l - margin_r, 0.32 * inch, fill=1, stroke=0)

        # Journal banner text
        canvas.setFillColor(white)
        canvas.setFont('Helvetica-Bold', 9)
        canvas.drawString(margin_l + 4, ph - margin_t - 0.32 * inch + 8,
                          'Veterinary Nanomedicine')
        canvas.setFont('Helvetica', 7.5)
        canvas.drawRightString(pw - margin_r - 4, ph - margin_t - 0.32 * inch + 8,
                               'Review Article  |  American Journal of Veterinary Research')

        # Thin blue rule below title block
        canvas.setStrokeColor(RULE_COLOR)
        canvas.setLineWidth(1.2)
        abstract_top = ph - margin_t - title_h
        canvas.line(margin_l, abstract_top, pw - margin_r, abstract_top)

        # Abstract background box
        abstract_h = 2.1 * inch
        canvas.setFillColor(LIGHT_BLUE)
        canvas.rect(margin_l, abstract_top - abstract_h,
                    pw - margin_l - margin_r, abstract_h, fill=1, stroke=0)
        canvas.setStrokeColor(RULE_COLOR)
        canvas.setLineWidth(0.6)
        canvas.rect(margin_l, abstract_top - abstract_h,
                    pw - margin_l - margin_r, abstract_h, fill=0, stroke=1)

        # Vertical gutter rule between columns (body area)
        body_top    = ph - margin_t - title_h - abstract_h - 0.1 * inch
        body_bottom = 0.85 * inch
        gutter_x    = margin_l + (pw - margin_l - margin_r - 0.25 * inch) / 2 + 0.125 * inch
        canvas.setStrokeColor(HexColor('#cccccc'))
        canvas.setLineWidth(0.4)
        canvas.line(gutter_x, body_bottom, gutter_x, body_top)

        canvas.restoreState()
        self._draw_footer(canvas, doc, 1)

    def _later_page_decorations(self, canvas, doc):
        canvas.saveState()
        pw, ph = PAGE_W, PAGE_H
        margin_l = 0.6 * inch
        margin_r = 0.6 * inch

        # Thin top rule
        canvas.setStrokeColor(RULE_COLOR)
        canvas.setLineWidth(0.8)
        canvas.line(margin_l, ph - 0.55 * inch, pw - margin_r, ph - 0.55 * inch)

        # Running header
        canvas.setFillColor(ACCENT_BLUE)
        canvas.setFont('Helvetica-Bold', 7.5)
        canvas.drawString(margin_l, ph - 0.45 * inch, 'Veterinary Nanomedicine')
        canvas.setFillColor(BODY_BLACK)
        canvas.setFont('Helvetica', 7.5)
        canvas.drawRightString(pw - margin_r, ph - 0.45 * inch,
                               'Nanomedicine in Veterinary Drug Delivery: Liposomes, Nanoparticles, and Targeted Therapy')

        # Vertical gutter rule
        margin_b = 0.85 * inch
        col_h    = ph - 0.75 * inch - margin_b
        col_w    = (pw - margin_l - margin_r - 0.25 * inch) / 2
        gutter_x = margin_l + col_w + 0.125 * inch
        canvas.setStrokeColor(HexColor('#cccccc'))
        canvas.setLineWidth(0.4)
        canvas.line(gutter_x, margin_b, gutter_x, margin_b + col_h)

        canvas.restoreState()
        self._draw_footer(canvas, doc, doc.page)


# --------------------------------------------------------
# Styles
# --------------------------------------------------------
def build_styles():
    s = {}

    # Journal name banner (rendered as Paragraph for first page frame)
    s['journal_banner'] = ParagraphStyle(
        'journal_banner',
        fontName='Helvetica-Bold',
        fontSize=8,
        textColor=HexColor('#888888'),
        leading=11,
        spaceBefore=8,
        spaceAfter=2,
    )
    s['article_title'] = ParagraphStyle(
        'article_title',
        fontName='Helvetica-Bold',
        fontSize=14.5,
        textColor=HEADER_BLUE,
        leading=18,
        spaceBefore=6,
        spaceAfter=4,
    )
    s['authors'] = ParagraphStyle(
        'authors',
        fontName='Helvetica-Bold',
        fontSize=8.5,
        textColor=ACCENT_BLUE,
        leading=12,
        spaceBefore=2,
        spaceAfter=1,
    )
    s['affiliations'] = ParagraphStyle(
        'affiliations',
        fontName='Helvetica-Oblique',
        fontSize=7.5,
        textColor=BODY_BLACK,
        leading=10,
        spaceBefore=1,
        spaceAfter=1,
    )
    s['corresponding'] = ParagraphStyle(
        'corresponding',
        fontName='Helvetica',
        fontSize=7.5,
        textColor=HexColor('#555555'),
        leading=10,
        spaceBefore=1,
        spaceAfter=4,
    )
    # Abstract section
    s['abstract_label'] = ParagraphStyle(
        'abstract_label',
        fontName='Helvetica-Bold',
        fontSize=8.5,
        textColor=ACCENT_BLUE,
        leading=11,
        spaceBefore=6,
        spaceAfter=2,
        leftIndent=6,
    )
    s['abstract_body'] = ParagraphStyle(
        'abstract_body',
        fontName='Helvetica',
        fontSize=7.8,
        textColor=BODY_BLACK,
        leading=11,
        spaceBefore=0,
        spaceAfter=2,
        leftIndent=6,
        rightIndent=6,
        alignment=TA_JUSTIFY,
    )
    s['keywords'] = ParagraphStyle(
        'keywords',
        fontName='Helvetica',
        fontSize=7.5,
        textColor=HexColor('#333333'),
        leading=10,
        spaceBefore=3,
        spaceAfter=0,
        leftIndent=6,
    )
    # Body
    s['section_heading'] = ParagraphStyle(
        'section_heading',
        fontName='Helvetica-Bold',
        fontSize=9,
        textColor=ACCENT_BLUE,
        leading=12,
        spaceBefore=10,
        spaceAfter=3,
    )
    s['subsection_heading'] = ParagraphStyle(
        'subsection_heading',
        fontName='Helvetica-Bold',
        fontSize=8.5,
        textColor=MEDIUM_BLUE,
        leading=11,
        spaceBefore=7,
        spaceAfter=2,
    )
    s['body'] = ParagraphStyle(
        'body',
        fontName='Helvetica',
        fontSize=8,
        textColor=BODY_BLACK,
        leading=11.5,
        spaceBefore=0,
        spaceAfter=4,
        alignment=TA_JUSTIFY,
    )
    s['reference_heading'] = ParagraphStyle(
        'reference_heading',
        fontName='Helvetica-Bold',
        fontSize=9,
        textColor=ACCENT_BLUE,
        leading=12,
        spaceBefore=10,
        spaceAfter=4,
    )
    s['reference'] = ParagraphStyle(
        'reference',
        fontName='Helvetica',
        fontSize=7.2,
        textColor=BODY_BLACK,
        leading=10,
        spaceBefore=0,
        spaceAfter=3,
        leftIndent=12,
        firstLineIndent=-12,
        alignment=TA_JUSTIFY,
    )
    s['table_header'] = ParagraphStyle(
        'table_header',
        fontName='Helvetica-Bold',
        fontSize=7.5,
        textColor=white,
        leading=10,
        alignment=TA_CENTER,
    )
    s['table_cell'] = ParagraphStyle(
        'table_cell',
        fontName='Helvetica',
        fontSize=7.2,
        textColor=BODY_BLACK,
        leading=10,
        alignment=TA_LEFT,
    )
    s['table_title'] = ParagraphStyle(
        'table_title',
        fontName='Helvetica-Bold',
        fontSize=8,
        textColor=BODY_BLACK,
        leading=11,
        spaceBefore=8,
        spaceAfter=3,
        alignment=TA_LEFT,
    )
    return s


# --------------------------------------------------------
# Build document content
# --------------------------------------------------------
def build_content(styles):
    story = []
    B = styles['body']
    H1 = styles['section_heading']
    H2 = styles['subsection_heading']

    # ---- HEADER FRAME content ----
    story.append(Paragraph(
        'Current Knowledge in Veterinary Pharmacology & Drug Delivery',
        styles['journal_banner']
    ))
    story.append(Paragraph(
        'Nanomedicine in Veterinary Drug Delivery: Liposomes, Nanoparticles, and Targeted Therapy',
        styles['article_title']
    ))
    story.append(Paragraph(
        'Priya R. Sharma, BVSc, MVSc<super>1*</super>, Daniel K. Hoffmann, PhD<super>2</super>, '
        'and Anjali S. Patel, DVM, PhD<super>3</super>',
        styles['authors']
    ))
    story.append(Paragraph(
        '<super>1</super>Department of Pharmacology &amp; Toxicology, College of Veterinary Science, '
        'Anand Agricultural University, Anand, Gujarat, India',
        styles['affiliations']
    ))
    story.append(Paragraph(
        '<super>2</super>Institute for Veterinary Pharmacology, Freie Universitat Berlin, Berlin, Germany',
        styles['affiliations']
    ))
    story.append(Paragraph(
        '<super>3</super>Department of Veterinary Clinical Sciences, Purdue University College of Veterinary '
        'Medicine, West Lafayette, IN',
        styles['affiliations']
    ))
    story.append(Paragraph(
        '*Corresponding author: Dr. Sharma (priya.sharma@aau.in)',
        styles['corresponding']
    ))

    # Transition to abstract frame
    story.append(FrameBreak())

    # ---- ABSTRACT FRAME ----
    story.append(Paragraph('ABSTRACT', styles['abstract_label']))
    abstract_text = (
        'The emergence of nanotechnology has fundamentally reshaped the landscape of drug delivery in '
        'veterinary medicine. Nanocarriers — including liposomes, polymeric nanoparticles, solid lipid '
        'nanoparticles, dendrimers, and metallic nanoparticles — offer tailored solutions to longstanding '
        'challenges in treating companion animals and livestock, such as poor drug bioavailability, rapid '
        'systemic clearance, off-target toxicity, and antimicrobial resistance. Liposomes, among the most '
        'clinically advanced platforms, have demonstrated efficacy in canine hemangiosarcoma, bovine mastitis, '
        'and parasitic vaccine delivery. Polymeric nanoparticles provide controlled, sustained release of '
        'antimicrobials, antiparasitics, and chemotherapeutics in multiple species. Active targeting '
        'strategies — using ligands, antibodies, or aptamers conjugated to nanocarrier surfaces — enable '
        'site-specific delivery and substantially reduce systemic adverse effects. This review integrates '
        'current evidence from in vitro studies, experimental animal models, and approved veterinary '
        'nanopharmaceuticals, while identifying knowledge gaps and barriers to wider clinical adoption, '
        'including species-specific pharmacokinetic variability, manufacturing scalability, regulatory '
        'pathways, and residue concerns in food-producing animals. Future directions encompass stimuli-responsive '
        'nanoplatforms, mRNA-lipid nanoparticle vaccines, and theranostic systems combining simultaneous '
        'diagnosis and therapy.'
    )
    story.append(Paragraph(abstract_text, styles['abstract_body']))
    story.append(Paragraph(
        '<b>Keywords:</b> nanomedicine, liposomes, polymeric nanoparticles, targeted drug delivery, '
        'veterinary pharmacology, theranostics, antimicrobial resistance, companion animals, livestock',
        styles['keywords']
    ))

    # Transition to two-column body
    story.append(FrameBreak())

    # ========================================================
    # BODY — LEFT COLUMN starts here
    # ========================================================

    story.append(Paragraph('Introduction', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))

    story.append(Paragraph(
        'The global veterinary pharmaceutical market exceeded USD 42 billion in 2023 and continues to expand '
        'rapidly, driven by increased companion animal ownership, intensification of livestock production, and '
        'rising awareness of antimicrobial stewardship. Despite this growth, a significant subset of veterinary '
        'drugs suffers from limitations that reduce clinical efficacy: hydrophobic molecules with poor aqueous '
        'solubility, short plasma half-lives necessitating frequent dosing, dose-dependent organ toxicity, and '
        'inability to penetrate biological barriers such as the blood-brain barrier or biofilm matrices.',
        B
    ))
    story.append(Paragraph(
        'Nanomedicine — the application of nanotechnology to medicine using materials at the 1–1,000 nm scale '
        '— addresses these limitations by encapsulating, conjugating, or adsorbing drug molecules onto or within '
        'nanocarriers. The resulting nanoformulations can modulate drug release kinetics, protect labile '
        'molecules from degradation, prolong circulation time, and direct payload delivery to target tissues '
        'or cells. These properties are directly applicable to veterinary contexts, where species diversity, '
        'body-weight variation, withdrawal-period mandates, and cost sensitivity impose unique constraints on '
        'formulation design.',
        B
    ))
    story.append(Paragraph(
        'This review systematically covers the principal nanocarrier platforms relevant to veterinary drug '
        'delivery — liposomes, polymeric nanoparticles (PNPs), solid lipid nanoparticles (SLNs), dendrimers, '
        'metallic nanoparticles, and nanoemulsions — with a focus on their mechanisms of action, species-specific '
        'applications, and the current state of clinical translation. We also address active versus passive '
        'targeting strategies, regulatory considerations, and future directions, including theranostic and '
        'stimuli-responsive systems.',
        B
    ))

    story.append(Paragraph('Liposomes', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))

    story.append(Paragraph('Structure and Physicochemical Properties', H2))
    story.append(Paragraph(
        'Liposomes are spherical vesicles composed of one or more phospholipid bilayers surrounding an aqueous '
        'core. Their amphiphilic architecture confers the unique ability to simultaneously encapsulate hydrophilic '
        'drugs in the aqueous core and hydrophobic drugs within the lipid bilayer. Classified by lamellarity and '
        'size, liposomes include small unilamellar vesicles (SUVs; 20–100 nm), large unilamellar vesicles '
        '(LUVs; 100–1,000 nm), and multilamellar vesicles (MLVs; >500 nm). Vesicle size profoundly influences '
        'biodistribution: SUVs circulate longer and exhibit preferential accumulation in inflamed or tumorous '
        'tissue via the enhanced permeability and retention (EPR) effect, while MLVs are rapidly cleared by '
        'the mononuclear phagocyte system (MPS).',
        B
    ))
    story.append(Paragraph(
        'Surface modification with poly(ethylene glycol) (PEG) — producing "stealth" liposomes — dramatically '
        'reduces opsonization and macrophage uptake, extending plasma half-life from minutes to hours or days. '
        'This strategy was pivotal in the development of PEGylated liposomal doxorubicin (Doxil®/Caelyx®) '
        'in human oncology and has been directly translated to veterinary oncology applications.',
        B
    ))

    story.append(Paragraph('Liposomes in Canine and Feline Oncology', H2))
    story.append(Paragraph(
        'The most extensively studied veterinary application of liposomes involves canine hemangiosarcoma (HSA). '
        'A landmark multicenter randomized clinical trial demonstrated that liposome-encapsulated muramyl '
        'tripeptide phosphatidylethanolamine (L-MTP-PE) administered as adjuvant immunotherapy significantly '
        'prolonged disease-free survival in dogs with splenic HSA following splenectomy. L-MTP-PE activates '
        'macrophages and monocytes, enhancing their tumoricidal activity; liposomal encapsulation directs the '
        'compound to these phagocytic cells and sustains its bioavailability.',
        B
    ))
    story.append(Paragraph(
        'More recently, panobinostat-loaded folate-targeted liposomes were evaluated against canine B-cell '
        'lymphoma. Folate receptors are overexpressed on neoplastic lymphocytes, providing a receptor-mediated '
        'active targeting mechanism. In vitro cytotoxicity assays confirmed enhanced uptake and superior '
        'antiproliferative activity compared to free panobinostat, supporting further in vivo validation. '
        'In feline patients, liposomal doxorubicin has been explored as a strategy to reduce nephrotoxicity — '
        'a critical concern given the heightened sensitivity of cats to conventional anthracyclines.',
        B
    ))

    story.append(Paragraph('Liposomes for Infectious Disease Management', H2))
    story.append(Paragraph(
        'Bovine mastitis, the costliest infectious disease of dairy cattle globally, has been a primary target '
        'for liposomal antibiotic delivery. Liposomal gentamicin formulations demonstrated in vivo efficacy '
        'against intracellular Salmonella enterica serovar Typhimurium in bovine mammary epithelial cells, '
        'overcoming the inability of free aminoglycosides to penetrate intracellular reservoirs. Similarly, '
        'enrofloxacin administered in PEGylated liposomes achieved greater intramammary tissue concentrations '
        'with lower systemic toxicity relative to conventional formulations.',
        B
    ))
    story.append(Paragraph(
        'Liposomal amphotericin B (AmBisome®) has been successfully used off-label in companion animal '
        'medicine for systemic fungal infections (aspergillosis, cryptococcosis, histoplasmosis) in dogs and '
        'cats, exploiting the pronounced reduction in nephrotoxicity conferred by liposomal encapsulation '
        'compared to conventional deoxycholate formulations. Liposomal tobramycin and ciprofloxacin have '
        'shown superior bactericidal activity in biofilm models of Pseudomonas aeruginosa — a major pathogen '
        'in chronic otitis and wound infections in dogs — by penetrating the extracellular matrix of biofilms '
        'more effectively than free drug.',
        B
    ))

    story.append(Paragraph('Liposomal Vaccine Delivery', H2))
    story.append(Paragraph(
        'Liposomes function as potent vaccine adjuvants by mimicking the lipid envelope of pathogens, '
        'facilitating antigen presentation to dendritic cells and macrophages. Liposome-based vaccines have '
        'been evaluated in ruminants against Theileria parva, Trypanosoma cruzi, and Leishmania spp., '
        'demonstrating stronger humoral and cell-mediated immune responses compared to conventional alum-based '
        'adjuvants. In aquaculture, liposomal delivery of fish vaccines has improved antigen stability and '
        'reduced the need for immunostimulatory additives, decreasing environmental contamination risk.',
        B
    ))

    # Column break — move to right column
    story.append(FrameBreak())

    story.append(Paragraph('Polymeric Nanoparticles', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))

    story.append(Paragraph('Composition and Fabrication', H2))
    story.append(Paragraph(
        'Polymeric nanoparticles (PNPs) are solid colloidal systems formed from natural or synthetic polymers '
        'in the 10–1,000 nm range. Biodegradable synthetic polymers — most notably poly(lactic-co-glycolic '
        'acid) (PLGA), polylactic acid (PLA), and polycaprolactone (PCL) — are the most widely used matrices '
        'owing to their FDA-approved status in human medicine, tunable degradation rates, and capacity for '
        'controlled, sustained drug release. Natural polymers, including chitosan, albumin, and gelatin, '
        'offer inherent biocompatibility and, in the case of chitosan, mucoadhesive and antimicrobial '
        'properties that are especially valuable for gastrointestinal and respiratory drug delivery in livestock.',
        B
    ))
    story.append(Paragraph(
        'Drug loading in PNPs is achieved through encapsulation within the polymer matrix (nanospheres) or '
        'within a polymeric shell surrounding an aqueous core (nanocapsules). Release kinetics are governed '
        'by polymer composition, molecular weight, degree of crosslinking, and surface coatings. PLGA '
        'microspheres and nanoparticles achieve biphasic release profiles: an initial burst from surface-adsorbed '
        'drug followed by sustained diffusion and polymer hydrolysis-driven release over days to weeks, '
        'dramatically reducing dosing frequency in production animals.',
        B
    ))

    story.append(Paragraph('Antimicrobial Applications in Livestock', H2))
    story.append(Paragraph(
        'Antimicrobial resistance (AMR) in veterinary pathogens is accelerating, paralleling trends in human '
        'medicine. PNP-based antibiotic delivery offers multiple mechanisms to combat AMR: (1) concentration '
        'of antibiotics at infection sites exceeds minimum inhibitory concentrations (MICs) even for resistant '
        'strains; (2) nanoparticle uptake by infected macrophages delivers drug directly to intracellular '
        'bacteria; (3) modified-release profiles maintain drug levels within the therapeutic window, minimizing '
        'sub-inhibitory exposure that drives resistance selection; and (4) combination loading of two '
        'antibiotics with different mechanisms within a single NP can provide synergistic killing.',
        B
    ))
    story.append(Paragraph(
        'PLGA nanoparticles loaded with rifampicin and isoniazid have been evaluated in bovine tuberculosis '
        'models, achieving equivalent mycobacterial killing with 3-fold fewer doses compared to conventional '
        'oral regimens. Chitosan nanoparticles encapsulating tilmicosin demonstrated sustained drug release '
        'and reduced cardiotoxicity — a major limitation of the free drug in cattle — in a '
        'bovine respiratory disease model. In aquaculture, PLGA NPs carrying florfenicol and delivered '
        'orally through feed achieved superior protection in rainbow trout against Aeromonas salmonicida '
        'compared to bath treatment.',
        B
    ))

    story.append(Paragraph('Antiparasitic Drug Delivery', H2))
    story.append(Paragraph(
        'Ivermectin, albendazole, and praziquantel — mainstays of veterinary antiparasitic therapy — are '
        'lipophilic molecules with inherently poor aqueous solubility that limit oral bioavailability. '
        'PLGA and lipid-polymer hybrid NPs have improved oral bioavailability of ivermectin by 2- to 4-fold '
        'in rodent models, with implications for dose reduction in treated livestock and reduced drug residue '
        'burdens in food products. Albendazole-loaded chitosan NPs enhanced gastrointestinal absorption in '
        'sheep and achieved superior anthelmintic efficacy against Haemonchus contortus with lower total '
        'drug dose, directly addressing withdrawal period constraints.',
        B
    ))

    # ----- TABLE -----
    story.append(Paragraph(
        'Table 1. Representative Nanocarrier Platforms in Veterinary Drug Delivery',
        styles['table_title']
    ))

    header_row = [
        Paragraph('Nanocarrier', styles['table_header']),
        Paragraph('Size Range', styles['table_header']),
        Paragraph('Key Drug(s)', styles['table_header']),
        Paragraph('Target Species', styles['table_header']),
        Paragraph('Primary Application', styles['table_header']),
    ]
    tc = styles['table_cell']
    data = [
        header_row,
        [Paragraph('Liposomes', tc), Paragraph('20–1000 nm', tc),
         Paragraph('L-MTP-PE, doxorubicin, gentamicin', tc),
         Paragraph('Dogs, cats, cattle', tc),
         Paragraph('Oncology, mastitis, fungal infections', tc)],
        [Paragraph('PLGA NPs', tc), Paragraph('100–500 nm', tc),
         Paragraph('Rifampicin, ivermectin, florfenicol', tc),
         Paragraph('Cattle, sheep, fish', tc),
         Paragraph('AMR infections, antiparasitic, aquaculture', tc)],
        [Paragraph('Chitosan NPs', tc), Paragraph('100–600 nm', tc),
         Paragraph('Tilmicosin, albendazole, vaccines', tc),
         Paragraph('Cattle, sheep, poultry', tc),
         Paragraph('BRD, anthelmintic, mucosal vaccines', tc)],
        [Paragraph('SLNs', tc), Paragraph('50–400 nm', tc),
         Paragraph('Cisplatin, amphotericin B', tc),
         Paragraph('Dogs, cats', tc),
         Paragraph('Oncology, systemic fungal disease', tc)],
        [Paragraph('Dendrimers', tc), Paragraph('2–10 nm', tc),
         Paragraph('siRNA, methotrexate', tc),
         Paragraph('Dogs (experimental)', tc),
         Paragraph('Gene therapy, targeted oncology', tc)],
        [Paragraph('Gold NPs', tc), Paragraph('5–100 nm', tc),
         Paragraph('Antibiotics, photothermal agents', tc),
         Paragraph('Dogs, cattle (experimental)', tc),
         Paragraph('Photothermal therapy, diagnostics', tc)],
        [Paragraph('Nanoemulsions', tc), Paragraph('100–500 nm', tc),
         Paragraph('Essential oils, insecticides', tc),
         Paragraph('Companion animals, livestock', tc),
         Paragraph('Ectoparasiticides, antimicrobials', tc)],
    ]

    col_widths = [1.0*inch, 0.75*inch, 1.45*inch, 1.1*inch, 1.4*inch]
    tbl = Table(data, colWidths=col_widths, repeatRows=1)
    tbl.setStyle(TableStyle([
        ('BACKGROUND',   (0, 0), (-1, 0),  HEADER_BLUE),
        ('TEXTCOLOR',    (0, 0), (-1, 0),  white),
        ('ALIGN',        (0, 0), (-1, -1), 'CENTER'),
        ('VALIGN',       (0, 0), (-1, -1), 'MIDDLE'),
        ('FONTNAME',     (0, 0), (-1,  0), 'Helvetica-Bold'),
        ('FONTSIZE',     (0, 0), (-1,  0), 7.5),
        ('FONTNAME',     (0, 1), (-1, -1), 'Helvetica'),
        ('FONTSIZE',     (0, 1), (-1, -1), 7),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [HexColor('#eaf4fc'), white]),
        ('GRID',         (0, 0), (-1, -1), 0.4, HexColor('#aaaaaa')),
        ('TOPPADDING',   (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING',(0, 0), (-1, -1), 3),
        ('LEFTPADDING',  (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
    ]))
    story.append(tbl)
    story.append(Spacer(1, 6))

    # Next page
    story.append(PageBreak())

    # ========================
    # PAGE 2 — LEFT COLUMN
    # ========================

    story.append(Paragraph('Solid Lipid Nanoparticles (SLNs)', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))
    story.append(Paragraph(
        'SLNs consist of a solid lipid matrix stabilized by surfactants at physiological temperature. '
        'They combine the biocompatibility advantages of liposomes with the physical stability of polymeric '
        'systems and can be produced by scalable high-pressure homogenization or microemulsion techniques. '
        'In veterinary oncology, SLN-encapsulated cisplatin has shown equivalent tumor cytotoxicity with '
        'markedly reduced nephrotoxicity in canine osteosarcoma cell lines, a critical consideration given '
        'that cisplatin is used commonly in dogs but is contraindicated in cats due to pulmonary edema.',
        B
    ))
    story.append(Paragraph(
        'Nanostructured lipid carriers (NLCs) — second-generation SLNs incorporating liquid lipid within '
        'the solid matrix to prevent drug expulsion during storage — have been evaluated for topical '
        'veterinary applications. NLC formulations of flunixin meglumine achieved superior dermal penetration '
        'in porcine skin ex vivo compared to conventional gels, suggesting utility for localized '
        'anti-inflammatory therapy in production animals without systemic exposure.',
        B
    ))

    story.append(Paragraph('Metallic and Inorganic Nanoparticles', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))
    story.append(Paragraph(
        'Silver nanoparticles (AgNPs) exhibit broad-spectrum intrinsic antimicrobial activity through '
        'disruption of bacterial cell membrane integrity, inhibition of enzyme function, and reactive oxygen '
        'species (ROS) generation. In veterinary contexts, AgNP-impregnated wound dressings have demonstrated '
        'accelerated healing and reduced bacterial bioburden in equine wounds. Colloidal silver formulations '
        'have been incorporated into teat dips and intrauterine infusions, though long-term biosafety data '
        'in production animals, particularly regarding meat and milk residues, remain limited.',
        B
    ))
    story.append(Paragraph(
        'Gold nanoparticles (AuNPs) are particularly valuable in theranostic applications. Their strong '
        'surface plasmon resonance enables precise photothermal ablation of tumor cells upon near-infrared '
        'irradiation. AuNP-based lateral flow assays have been developed for rapid on-farm detection of '
        'bovine viral diarrhea virus (BVDV), porcine reproductive and respiratory syndrome virus (PRRSV), '
        'and Brucella antibodies, combining diagnostic sensitivity with field-deployable ease of use.',
        B
    ))
    story.append(Paragraph(
        'Zinc oxide nanoparticles (ZnO NPs) are used as antimicrobial feed additives in swine production, '
        'partially replacing pharmacological zinc oxide in post-weaning piglets as a strategy to reduce '
        'enteric colibacillosis. However, their environmental persistence and potential contribution to '
        'metal resistance in soil microbiomes have prompted regulatory restrictions in the European Union, '
        'highlighting the need for comprehensive environmental impact assessments of nanomaterials in '
        'food animal production.',
        B
    ))

    story.append(Paragraph('Targeted Therapy: Passive and Active Strategies', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))

    story.append(Paragraph('Passive Targeting via the EPR Effect', H2))
    story.append(Paragraph(
        'In solid tumors, rapid angiogenesis produces fenestrated vasculature with pore sizes of 200–1,200 nm, '
        'while impaired lymphatic drainage leads to nanoparticle accumulation within the tumor interstitium — '
        'the EPR effect. Nanoparticles in the 20–200 nm size range exploit this passive targeting to achieve '
        'tumor drug concentrations 10- to 50-fold higher than free drug, substantially improving therapeutic '
        'index. This mechanism has been validated in canine and feline solid tumors, particularly mast cell '
        'tumors and injection-site sarcomas in cats, justifying the clinical development of PEGylated '
        'liposomal doxorubicin in these species.',
        B
    ))

    story.append(Paragraph('Active Targeting Strategies', H2))
    story.append(Paragraph(
        'Active targeting conjugates targeting ligands to nanocarrier surfaces, enabling receptor-mediated '
        'endocytosis at specific cell types. Strategies evaluated in veterinary nanomedicine include:',
        B
    ))
    story.append(Paragraph(
        '<b>Folate receptor targeting:</b> Folate receptors are overexpressed on many canine and feline '
        'lymphoma and carcinoma cells. Folate-conjugated liposomes and PNPs have demonstrated superior '
        'intracellular drug accumulation in neoplastic versus normal lymphocytes, providing a selectivity '
        'window that could reduce bone marrow suppression.',
        B
    ))
    story.append(Paragraph(
        '<b>Antibody-conjugated nanoparticles (immunoliposomes):</b> Monoclonal antibodies against '
        'species-specific tumor-associated antigens (e.g., CD20 in canine B-cell lymphoma, HER2/neu in '
        'canine mammary tumors) can be conjugated to nanocarrier surfaces. Immunoliposomes bearing '
        'anti-CD20 fragments have shown enhanced cytotoxicity against canine lymphoma cell lines, '
        'combining antibody-mediated killing with intracellular drug delivery.',
        B
    ))
    story.append(Paragraph(
        '<b>Aptamer-functionalized nanoparticles:</b> Nucleic acid aptamers with high binding affinity for '
        'veterinary pathogens or tumor-associated antigens offer a synthetic alternative to antibodies '
        'with lower manufacturing costs. Aptamer-decorated PLGA NPs have been developed for targeting '
        'Staphylococcus aureus biofilms in bovine mastitis, achieving superior intrabiofilm drug penetration '
        'compared to unconjugated nanoparticles.',
        B
    ))

    story.append(FrameBreak())

    # ========================
    # PAGE 2 — RIGHT COLUMN
    # ========================

    story.append(Paragraph('Species-Specific Pharmacokinetic Considerations', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))
    story.append(Paragraph(
        'A fundamental challenge in translating nanomedicine from laboratory to veterinary clinic is the '
        'pronounced inter-species variability in pharmacokinetics that determines nanocarrier fate in vivo. '
        'Key parameters include mononuclear phagocyte system (MPS) activity, plasma protein composition, '
        'gastrointestinal transit time and pH, hepatic and renal clearance capacity, and body surface area '
        'relative to weight. Cats, for example, have reduced hepatic glucuronidation capacity, altering the '
        'metabolism of lipid-based nanocarrier components. Ruminants present unique challenges: the '
        'forestomach (rumen, reticulum, omasum) can degrade lipid-based nanoparticles before absorption '
        'occurs in the abomasum and small intestine.',
        B
    ))
    story.append(Paragraph(
        'Body weight in veterinary species spans six orders of magnitude — from a 30-g laboratory mouse '
        'to a 600-kg draft horse — and allometric scaling principles used to extrapolate doses must account '
        'for nanoparticle-specific distribution volumes. Plasma protein binding of nanoparticle surfaces '
        '(the "protein corona") is increasingly recognized as a key determinant of nanocarrier biodistribution '
        'and is incompletely characterized across veterinary species. Systematic studies mapping protein '
        'corona formation in canine, feline, bovine, equine, and porcine plasma are urgently needed.',
        B
    ))

    story.append(Paragraph('Approved and Commercially Available Veterinary Nanopharmaceuticals', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))
    story.append(Paragraph(
        'Despite the breadth of preclinical research, the number of regulatory-approved veterinary '
        'nanopharmaceuticals remains limited. Nocita® (bupivacaine liposome injectable suspension, Aratana '
        'Therapeutics/Elanco), approved by the USDA in 2016, is the most notable example — a liposomal '
        'bupivacaine formulation providing up to 72 hours of postoperative analgesia following cranial '
        'cruciate ligament repair in dogs. This product demonstrated that liposomal drug delivery in '
        'companion animals can achieve regulatory approval and commercial viability, providing a template '
        'for future submissions.',
        B
    ))
    story.append(Paragraph(
        'AmBisome® (liposomal amphotericin B) is used off-label in dogs and cats for systemic mycoses, '
        'and a small number of liposomal antibiotic and vaccine formulations are commercially available '
        'in specific markets. The disparity between the volume of preclinical research and the number of '
        'approved products reflects significant regulatory, manufacturing, and commercial barriers that '
        'must be addressed to accelerate clinical translation.',
        B
    ))

    story.append(Paragraph('Regulatory Landscape and Barriers to Translation', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))
    story.append(Paragraph(
        'Veterinary nanopharmaceuticals are evaluated by the USDA (biologics), FDA Center for Veterinary '
        'Medicine (CVM; drugs and devices), and their international equivalents (EMA, APVMA, CFIA). Unlike '
        'human nanomedicine, for which the FDA issued draft guidance on characterization and preclinical '
        'testing of nanoparticle drug products, no equivalent veterinary-specific guidance documents currently '
        'exist. Manufacturers must navigate existing frameworks originally designed for conventional drug '
        'formulations, applying nanotechnology-specific characterization data (hydrodynamic diameter, '
        'polydispersity index, zeta potential, encapsulation efficiency, drug release profiles) within '
        'a regulatory structure that may not yet fully account for these parameters.',
        B
    ))
    story.append(Paragraph(
        'For food-producing animals, residue depletion studies must demonstrate that nanocarrier components '
        'and encapsulated drugs do not persist in milk, eggs, or meat above maximum residue limits (MRLs). '
        'The fate of nanocarrier excipients — PLGA degradation products, PEG chains, lipid components — '
        'in edible tissues is poorly characterized and represents a significant data gap. Environmental '
        'risk assessment of nanomaterials excreted by treated animals into soil and water ecosystems '
        'is an emerging regulatory requirement, particularly in Europe.',
        B
    ))

    story.append(Paragraph('Future Directions', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))

    story.append(Paragraph('Stimuli-Responsive Nanoplatforms', H2))
    story.append(Paragraph(
        'Next-generation nanocarriers are engineered to release payload in response to specific '
        'microenvironmental stimuli: pH reduction in infected or tumorous tissues, elevated '
        'matrix metalloproteinase (MMP) activity, reactive oxygen species (ROS), localized hyperthermia, '
        'or external triggers such as ultrasound or near-infrared light. pH-responsive PLGA NPs that '
        'release antibiotic preferentially in the acidic phagolysosomal environment of infected macrophages '
        'could dramatically improve intracellular bacterial killing in bovine brucellosis and feline '
        'bartonellosis. Thermoresponsive liposomes combined with hyperthermia devices have been evaluated '
        'in canine soft tissue sarcomas in proof-of-concept studies.',
        B
    ))

    story.append(Paragraph('mRNA-Lipid Nanoparticle Vaccines', H2))
    story.append(Paragraph(
        'The clinical validation of mRNA-lipid nanoparticle (LNP) vaccines in humans during the COVID-19 '
        'pandemic has accelerated their evaluation in veterinary species. mRNA-LNP vaccines against foot-and-'
        'mouth disease virus (FMDV), African swine fever virus (ASFV), and avian influenza have entered '
        'preclinical development, leveraging the same ionizable lipid formulations (e.g., SM-102, ALC-0315) '
        'validated in humans. Key challenges in veterinary adaptation include LNP stability at ambient '
        'temperatures relevant to field conditions, intramuscular versus intranasal delivery optimization '
        'for mucosal immunity in respiratory pathogens, and species-specific adjuvant requirements.',
        B
    ))

    story.append(Paragraph('Theranostics', H2))
    story.append(Paragraph(
        'Theranostic nanoplatforms integrate diagnostic imaging agents with therapeutic payloads within '
        'a single nanocarrier, enabling real-time monitoring of drug biodistribution and tumor response. '
        'Iron oxide nanoparticles (IONPs) functionalized with doxorubicin and targeted against canine '
        'osteosarcoma cells have been evaluated as MRI-trackable, magnetically guided drug delivery vehicles. '
        'The ability to confirm intratumoral drug accumulation by imaging prior to committing full therapeutic '
        'dose represents a paradigm shift in personalized veterinary oncology.',
        B
    ))

    story.append(Paragraph('Knowledge Gaps and Future Research Priorities', H1))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=4))
    story.append(Paragraph(
        'Significant knowledge gaps hinder the full realization of nanomedicine in veterinary practice. '
        'The protein corona formed by plasma proteins around nanoparticles upon systemic administration '
        'fundamentally alters biodistribution and cellular uptake, yet has been systematically '
        'characterized in only a handful of veterinary species. Long-term nanotoxicology studies in '
        'companion animals and target food-animal species are sparse, with most safety data derived '
        'from rodent surrogates with limited translational validity.',
        B
    ))
    story.append(Paragraph(
        'Manufacturing scalability and batch-to-batch reproducibility of complex nanoformulations '
        'remain significant industry barriers, with current Good Manufacturing Practice (cGMP) '
        'compliance requirements adding substantial cost. Intellectual property landscapes for key '
        'excipients and manufacturing processes create licensing challenges for smaller veterinary '
        'pharmaceutical companies. Collaborative frameworks between academic veterinary colleges, '
        'regulatory agencies, and industry — analogous to the Critical Path Initiative in human '
        'medicine — are needed to generate the structured preclinical and clinical datasets required '
        'for regulatory submissions.',
        B
    ))

    # References
    story.append(PageBreak())

    story.append(Paragraph('References', styles['reference_heading']))
    story.append(HRFlowable(width='100%', thickness=0.6, color=RULE_COLOR, spaceAfter=6))

    references = [
        '1. Vail DM, MacEwen EG, Kurzman ID, et al. Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine adjuvant immunotherapy for splenic hemangiosarcoma in the dog: a randomized multi-institutional clinical trial. Clin Cancer Res. 1995;1:1165–1170.',
        '2. Jafary F, Motamedi S, Karimi I. Veterinary nanomedicine: pros and cons. Vet Med Sci. 2023;9(1):1–14. doi:10.1002/vms3.1050',
        '3. Zabielska-Kocziywas K, Lechowski R. The use of liposomes and nanoparticles as drug delivery systems to improve cancer treatment in dogs and cats. Molecules. 2017;22:2167. doi:10.3390/molecules22122167',
        '4. Bai D-P, Lin X-Y, Huang Y-F, Zhang X-F. Theranostics aspects of various nanoparticles in veterinary medicine. Int J Mol Sci. 2018;19:3299. doi:10.3390/ijms19113299',
        '5. Andre AS, Dias JNR, Aguiar SI, et al. Panobinostat-loaded folate targeted liposomes as a promising drug delivery system for treatment of canine B-cell lymphoma. Front Vet Sci. 2023;10. doi:10.3389/fvets.2023.1107451',
        '6. Sarfraz M, Khalid S, Hassaan S, et al. Meeting contemporary challenges: development of nanomaterials for veterinary medicine. Nanomaterials. 2023;13:2884. doi:10.3390/nano13212884',
        '7. MacLeod DL, Prescott JF. The use of liposomally entrapped gentamicin in the treatment of bovine Staphylococcus aureus mastitis. Can J Vet Res. 1988;52:445–450.',
        '8. Benites NR, Melville PA. Applications of nanotechnology in veterinary medicine: a brief overview. Rev Bras Med Vet. 2014;36:283–290.',
        '9. Farjadian F, Ghasemi A, Gohari O, et al. Nanopharmaceuticals and nanomedicines currently on the market: challenges and opportunities. Nanomedicine. 2019;14:93–126.',
        '10. FDA. NADA 141-461 Nocita® dog. Freedom of information summary: original new animal drug application. US FDA; 2016.',
        '11. Torchilin VP. Multifunctional, stimuli-sensitive nanoparticulate systems for drug delivery. Nat Rev Drug Discov. 2014;13:813–827.',
        '12. Masood F. Polymeric nanoparticles for targeted drug delivery system for cancer therapy. Mater Sci Eng C. 2016;60:569–578.',
        '13. Cullis PR, Felgner PL. The 60-year evolution of lipid nanoparticles for nucleic acid delivery. Nat Rev Drug Discov. 2024;23:709–722.',
        '14. Cau MF, Ferraresso F, Seadler M, et al. siRNA-mediated reduction of a circulating protein in swine using lipid nanoparticles. Mol Ther Methods Clin Dev. 2024;32:101258.',
        '15. Patra JK, Das G, Fraceto LF, et al. Nano based drug delivery systems: recent developments and future prospects. J Nanobiotechnol. 2018;16:71. doi:10.1186/s12951-018-0392-8',
        '16. Liang H, He J. Applications of liposomal drug delivery systems in veterinary medicine: a review. Pak J Agric Sci. 2021;58(suppl 1):1–12.',
        '17. Wang Z, Guo W, Kuang X, Hou S, Liu H. Nanopreparations for mitochondria targeting drug delivery system: current strategies and future prospective. Asian J Pharm Sci. 2017;12:498–508.',
        '18. He H, Guo J, Xu B. Enzymatic delivery of magnetic nanoparticles into mitochondria of live cells. ChemNanoMat. 2021;7:1104–1107.',
    ]
    for ref in references:
        story.append(Paragraph(ref, styles['reference']))

    return story


# --------------------------------------------------------
# Main
# --------------------------------------------------------
def main():
    output_path = '/tmp/workspace/nanomedicine-vet-pdf/Nanomedicine_Veterinary_Drug_Delivery.pdf'

    doc = TwoColumnDoc(
        output_path,
        pagesize=letter,
        leftMargin=0.6 * inch,
        rightMargin=0.6 * inch,
        topMargin=0.75 * inch,
        bottomMargin=0.85 * inch,
    )

    styles = build_styles()
    story  = build_content(styles)
    doc.build(story)
    print(f'PDF created: {output_path}')


if __name__ == '__main__':
    main()