List of all the drug calculation formulas for adults and paediatric with examples

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drug calculation formulas adults paediatric nursing complete list with examples

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https://nurseslabs.com/pediatric-dosage-calculations

I now have comprehensive information to deliver a thorough, well-organized answer. Here is the complete reference:

Drug Calculation Formulas - Complete Reference (Adults & Paediatric)

UNIT CONVERSIONS (Essential Foundation)

Metric	Equivalent
1 microgram (mcg)	0.000001 g (1/1000 mg)
1 milligram (mg)	0.001 g / 1000 mcg
1 gram (g)	1000 mg
1 kilogram (kg)	1000 g / 2.2 lbs
1 milliliter (mL)	0.001 L
1 teaspoon	5 mL
1 tablespoon	15 mL / 3 tsp
1 fluid ounce	30 mL

SECTION A: GENERAL / ADULT DRUG CALCULATION FORMULAS

1. Basic Dose Formula (D/H x V)

The most widely used formula in nursing practice.

Dose to give = (Desired dose / Have on hand) x Vehicle

D = Desired dose (what is ordered)
H = Have on hand (available concentration)
V = Vehicle (tablet, mL, capsule)

Example 1 - Oral liquid: Order: Acetaminophen 500 mg | On hand: 250 mg/5 mL

= (500 / 250) x 5 mL = 2 x 5 = 10 mL

Example 2 - Tablets: Order: Digoxin 0.25 mg | On hand: 0.125 mg/tablet

= (0.25 / 0.125) x 1 = 2 tablets

2. Ratio and Proportion Method

H : V = D : X
(cross-multiply to solve for X)

Example: Order: Erythromycin 750 mg | On hand: 250 mg capsules

250 : 1 = 750 : X
250X = 750
X = 3 capsules

3. IV Drip Rate Formula (drops/min - gtt/min)

Drip rate (gtt/min) = (Volume to infuse in mL x Drop factor) / Time in minutes

Drop factor (from IV tubing): Macro-drip = 10, 15, or 20 gtt/mL | Micro-drip = 60 gtt/mL

Example: Order: 1000 mL NS over 8 hours, tubing = 20 gtt/mL

Time = 8 x 60 = 480 minutes
Drip rate = (1000 x 20) / 480 = 20,000 / 480 = 41.7 ≈ 42 gtt/min

4. IV Flow Rate Formula (mL/hour)

Flow rate (mL/hr) = Total volume (mL) / Total time (hours)

Example: Order: 500 mL D5W over 4 hours

Flow rate = 500 / 4 = 125 mL/hr

5. Infusion Time Formula

Infusion time (hours) = Total volume (mL) / Flow rate (mL/hr)

Example: 1 L (1000 mL) infusing at 125 mL/hr

Time = 1000 / 125 = 8 hours

6. Weight-Based Dosing (mg/kg)

Dose = Ordered dose (mg/kg) x Patient weight (kg)

Example: Order: Amoxicillin 25 mg/kg | Patient weight: 70 kg

Dose = 25 x 70 = 1750 mg per dose

7. Weight-Based IV Infusion Rate (mcg/kg/min)

mL/hr = (Dose in mcg/kg/min x Weight in kg x 60) / Concentration in mcg/mL

Example: Dopamine 5 mcg/kg/min | Patient: 80 kg | Bag: 400 mg in 250 mL

Concentration = 400,000 mcg / 250 mL = 1600 mcg/mL

mL/hr = (5 x 80 x 60) / 1600 = 24,000 / 1600 = 15 mL/hr

8. Reconstitution Formula

Amount to administer = (Desired dose / Available dose) x Volume after reconstitution

Example: Order: Ampicillin 500 mg IV | Vial: 1 g powder, reconstituted with 10 mL = 100 mg/mL

= (500 mg / 100 mg) x 1 mL = 5 mL

9. Percent Solution Formula

% Solution = (Amount of drug in g / Total volume in mL) x 100

Example: 10 g of dextrose in 100 mL = 10% dextrose solution

10. Units-Based Dosing (e.g., Insulin, Heparin)

Volume to give (mL) = Units ordered / Units per mL available

Example: Order: Heparin 5000 units SC | Available: 10,000 units/mL

= 5000 / 10,000 = 0.5 mL

11. Body Surface Area (BSA) - Mosteller Formula

BSA (m²) = √[ Height (cm) x Weight (kg) / 3600 ]

Example: Patient: 170 cm tall, 70 kg

BSA = √(170 x 70 / 3600) = √(11900/3600) = √3.306 = 1.82 m²

12. BSA-Based Dose

Dose = BSA (m²) x Dose per m²

Example: Chemotherapy drug: 50 mg/m² | BSA: 1.82 m²

Dose = 1.82 x 50 = 91 mg

13. Creatinine Clearance - Cockcroft-Gault Formula (renal dose adjustment)

CrCl (mL/min) = [ (140 - Age) x Weight (kg) ] / [ 72 x Serum Creatinine (mg/dL) ]
(Multiply by 0.85 for females)

Example: 65-year-old male, 70 kg, creatinine 1.2 mg/dL

CrCl = (140 - 65) x 70 / (72 x 1.2) = 75 x 70 / 86.4 = 5250 / 86.4 = 60.8 mL/min

SECTION B: PAEDIATRIC DRUG CALCULATION FORMULAS

Paediatric doses are almost always based on weight (mg/kg), but several age-based rules are also used to estimate doses when only the adult dose is known.

14. Weight-Based Dose (mg/kg) - Most Preferred Paediatric Method

Child's dose = Ordered dose (mg/kg) x Child's weight (kg)

Example: Order: Paracetamol 15 mg/kg | Child weighs: 20 kg

Dose = 15 x 20 = 300 mg

Safe dose range check: If safe range is 10-15 mg/kg for a 20 kg child, safe range = 200-300 mg.

15. Young's Rule (for children 2-12 years, uses age in years)

Child's dose = [ Age (years) / (Age + 12) ] x Adult dose

Example: 10-year-old child | Adult dose of Paracetamol: 500 mg

= [10 / (10 + 12)] x 500
= [10 / 22] x 500
= 0.455 x 500 = 227.5 mg ≈ 225 mg

16. Fried's Rule (for infants under 2 years, uses age in months)

Child's dose = [ Age (months) / 150 ] x Adult dose

Example: 2-year-old (24 months) | Adult dose: 500 mg

= [24 / 150] x 500
= 0.16 x 500 = 80 mg

17. Clark's Rule (uses weight in pounds - lb)

Child's dose = [ Weight of child (lb) / 150 lb ] x Adult dose

Note: Use weight in pounds only, never kilograms, for this formula. Average adult weight = 150 lbs.

Example: Child weighs 60 lbs | Adult dose of Amoxicillin: 500 mg

= [60 / 150] x 500
= 0.4 x 500 = 200 mg

18. BSA-Based Paediatric Dose (West Nomogram method)

Child's dose = (Child's BSA in m² / 1.7 m²) x Adult dose

Average adult BSA = 1.7 m²
Child's BSA is found using the West Nomogram (plot height on left scale against weight on right scale; read BSA from the SA column)

Example: Child: 37 inches tall, 34 lbs (BSA from nomogram = 0.64 m²) | Adult dose: 500 mg

= (0.64 / 1.7) x 500
= 0.38 x 500 = 190 mg

BSA via Mosteller formula (for children):

BSA = √[ Height (cm) x Weight (kg) / 3600 ]

Child: 100 cm tall, 16.4 kg

BSA = √(100 x 16.4 / 3600) = √(1640/3600) = √0.456 = 0.675 m²

19. Paediatric IV Drip Rate (same formula as adults)

Drip rate (gtt/min) = (Volume x Drop factor) / Time in minutes

Paediatric IV sets typically use 60 gtt/mL (micro-drip) for accuracy with small volumes.

Example: Order: 100 mL over 4 hours, micro-drip tubing (60 gtt/mL)

Time = 4 x 60 = 240 min
Drip rate = (100 x 60) / 240 = 6000 / 240 = 25 gtt/min

20. Safe Dose Range Check (Paediatric)

Always verify the calculated dose falls within the published safe range.

Low safe dose = Low mg/kg x Child's weight (kg)
High safe dose = High mg/kg x Child's weight (kg)

Example: Safe range: 10-30 mg/kg | Child weighs 20 kg

Low = 10 x 20 = 200 mg
High = 30 x 20 = 600 mg
→ Prescribed dose must fall between 200-600 mg to be safe

QUICK SUMMARY TABLE

Formula	Used For	Key Variable
D/H x V	Any oral/parenteral dose	Desired, Have, Vehicle
Ratio & Proportion	Dose calculation	Cross multiply
Drip rate (gtt/min)	IV gravity infusion	Drop factor, time
mL/hr	IV pump rate	Volume, time
mg/kg	Weight-based dosing (all ages)	Patient weight
mcg/kg/min	Vasoactive drips	Concentration, weight
Reconstitution	Powder vials	Post-reconstitution conc.
BSA (Mosteller)	Chemo, high-risk drugs	Height, weight
Cockcroft-Gault	Renal dose adjustment	Age, weight, creatinine
Young's Rule	Paediatric (2-12 yrs)	Age in years
Fried's Rule	Infants (<2 yrs)	Age in months
Clark's Rule	Paediatric (weight-based)	Weight in lbs
BSA Paediatric	Paediatric/chemo doses	BSA vs 1.7 m²
Safe Dose Range	Paediatric safety check	mg/kg range x weight

Key clinical reminders:

Always double-check units before calculating (mg vs mcg vs g)
Weight-based dosing (mg/kg) is the gold standard for paediatrics
Age-based rules (Young's, Fried's, Clark's) are estimates only - use mg/kg when possible
Always perform a safe dose range check for paediatric patients before administration
For high-alert drugs (insulin, heparin, chemotherapy), always have a second nurse verify calculations

Create a quick reference PDF or pocket guide for drug calculation formulas

Reading File

Running Command

ls /home/daytona/workspace/

Running Command

mkdir -p /home/daytona/workspace/drug-calc-guide

Writing File

~/drug-calc-guide/generate_guide.py

from reportlab.lib.pagesizes import A4
from reportlab.lib import colors
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm, mm
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
    HRFlowable, KeepTogether, PageBreak
)
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_RIGHT
from reportlab.pdfgen import canvas
from reportlab.platypus.flowables import Flowable

# ── Colour Palette ────────────────────────────────────────────────
NAVY       = colors.HexColor("#0D2B55")
TEAL       = colors.HexColor("#0B7FA0")
TEAL_LIGHT = colors.HexColor("#D6F0F7")
GREEN      = colors.HexColor("#0A6E44")
GREEN_LIGHT= colors.HexColor("#D4EDDA")
AMBER      = colors.HexColor("#B45309")
AMBER_LIGHT= colors.HexColor("#FEF3C7")
RED        = colors.HexColor("#9B1C1C")
RED_LIGHT  = colors.HexColor("#FEE2E2")
PURPLE     = colors.HexColor("#5B21B6")
PURPLE_LIGHT=colors.HexColor("#EDE9FE")
GREY_DARK  = colors.HexColor("#374151")
GREY_MID   = colors.HexColor("#6B7280")
GREY_LIGHT = colors.HexColor("#F3F4F6")
WHITE      = colors.white
BLACK      = colors.black

PAGE_W, PAGE_H = A4
MARGIN = 1.6 * cm

# ── Styles ─────────────────────────────────────────────────────────
styles = getSampleStyleSheet()

def S(name, **kw):
    return ParagraphStyle(name, **kw)

TITLE_STYLE = S("MainTitle",
    fontName="Helvetica-Bold", fontSize=22, textColor=WHITE,
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SUBTITLE_STYLE = S("SubTitle",
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    alignment=TA_CENTER, spaceAfter=2)

SECTION_HEADER = S("SectionH",
    fontName="Helvetica-Bold", fontSize=11, textColor=WHITE,
    alignment=TA_LEFT, leftIndent=6, spaceBefore=4, spaceAfter=2)

FORMULA_NAME = S("FormName",
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FORMULA_BOX = S("FormBox",
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    leftIndent=8, spaceBefore=1, spaceAfter=1)

BODY = S("Body",
    fontName="Helvetica", fontSize=8.5, textColor=GREY_DARK,
    leftIndent=8, spaceBefore=1, spaceAfter=1)

EXAMPLE_LABEL = S("ExLabel",
    fontName="Helvetica-BoldOblique", fontSize=8, textColor=TEAL,
    leftIndent=8, spaceBefore=1)

EXAMPLE_TEXT = S("ExText",
    fontName="Helvetica-Oblique", fontSize=8, textColor=GREY_DARK,
    leftIndent=16, spaceAfter=2)

NOTE = S("Note",
    fontName="Helvetica-Oblique", fontSize=7.5, textColor=GREY_MID,
    leftIndent=8, spaceAfter=2)

TABLE_HEADER = S("TH",
    fontName="Helvetica-Bold", fontSize=8, textColor=WHITE,
    alignment=TA_CENTER)

TABLE_CELL = S("TC",
    fontName="Helvetica", fontSize=7.5, textColor=GREY_DARK,
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FOOTER_STYLE = S("Footer",
    fontName="Helvetica-Oblique", fontSize=7, textColor=GREY_MID,
    alignment=TA_CENTER)

WARNING = S("Warn",
    fontName="Helvetica-Bold", fontSize=8, textColor=RED,
    leftIndent=8, spaceAfter=2)


# ── Helper Flowables ───────────────────────────────────────────────
def section_bar(title, color=TEAL):
    """Coloured section header bar."""
    data = [[Paragraph(title, SECTION_HEADER)]]
    t = Table(data, colWidths=[PAGE_W - 2*MARGIN])
    t.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), color),
        ("TOPPADDING",    (0,0), (-1,-1), 5),
        ("BOTTOMPADDING", (0,0), (-1,-1), 5),
        ("LEFTPADDING",   (0,0), (-1,-1), 8),
        ("ROUNDEDCORNERS", [4, 4, 4, 4]),
    ]))
    return t

def formula_card(name, formula_lines, example_steps, note=None,
                 bg_color=TEAL_LIGHT, accent=TEAL):
    """A single formula card."""
    col_w = PAGE_W - 2*MARGIN
    content = []
    content.append(Paragraph(name, FORMULA_NAME))
    for fl in formula_lines:
        content.append(Paragraph(fl, FORMULA_BOX))
    content.append(Paragraph("Example:", EXAMPLE_LABEL))
    for es in example_steps:
        content.append(Paragraph(es, EXAMPLE_TEXT))
    if note:
        content.append(Paragraph(f"&#9432; {note}", NOTE))

    data = [[content]]
    t = Table(data, colWidths=[col_w])
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), bg_color),
        ("LINECOLOR",     (0,0), (-1,-1), accent),
        ("LINEBEFORE",    (0,0), (0,-1), 3, accent),
        ("TOPPADDING",    (0,0), (-1,-1), 6),
        ("BOTTOMPADDING", (0,0), (-1,-1), 6),
        ("LEFTPADDING",   (0,0), (-1,-1), 10),
        ("RIGHTPADDING",  (0,0), (-1,-1), 8),
    ]))
    return t

def two_col_cards(left_items, right_items, bg=TEAL_LIGHT, accent=TEAL):
    """Two formula cards side by side."""
    col_w = (PAGE_W - 2*MARGIN - 4*mm) / 2

    def make_cell(items):
        content = []
        for item in items:
            content.append(item)
        return content

    data = [[make_cell(left_items), make_cell(right_items)]]
    t = Table(data, colWidths=[col_w, col_w], hAlign="LEFT")
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), bg),
        ("LINEBEFORE",    (0,0), (0,-1), 3, accent),
        ("LINEBEFORE",    (1,0), (1,-1), 3, accent),
        ("TOPPADDING",    (0,0), (-1,-1), 6),
        ("BOTTOMPADDING", (0,0), (-1,-1), 6),
        ("LEFTPADDING",   (0,0), (-1,-1), 8),
        ("RIGHTPADDING",  (0,0), (-1,-1), 6),
        ("VALIGN",        (0,0), (-1,-1), "TOP"),
    ]))
    return t


# ── Page Template with header/footer ──────────────────────────────
class DrugCalcDoc(SimpleDocTemplate):
    def __init__(self, filename):
        super().__init__(
            filename,
            pagesize=A4,
            leftMargin=MARGIN, rightMargin=MARGIN,
            topMargin=MARGIN + 0.2*cm, bottomMargin=MARGIN,
            title="Drug Calculation Pocket Guide",
            author="Clinical Reference",
            subject="Drug Dosage Formulas - Adults & Paediatrics"
        )
        self.page_num = 0

    def handle_pageBegin(self):
        self.page_num += 1
        super().handle_pageBegin()

    def afterPage(self):
        c = self.canv
        w, h = A4
        c.saveState()
        # Footer line
        c.setStrokeColor(TEAL)
        c.setLineWidth(0.5)
        c.line(MARGIN, 1.0*cm, w - MARGIN, 1.0*cm)
        # Footer text
        c.setFont("Helvetica-Oblique", 7)
        c.setFillColor(GREY_MID)
        c.drawString(MARGIN, 0.65*cm,
            "Drug Calculation Pocket Guide  |  For educational use only  |  Always verify doses with current formulary")
        c.drawRightString(w - MARGIN, 0.65*cm, f"Page {self._pagenum}")
        c.restoreState()


# ── Build Content ─────────────────────────────────────────────────
def build_title_block():
    """Hero banner drawn directly - returns a Table that looks like a banner."""
    col_w = PAGE_W - 2*MARGIN
    title_para = Paragraph("Drug Calculation<br/>Pocket Guide", TITLE_STYLE)
    sub_para   = Paragraph(
        "Adults &amp; Paediatrics  |  Quick Reference for Nurses &amp; Clinicians",
        SUBTITLE_STYLE)
    note_para  = Paragraph(
        "Covers oral doses, IV infusions, weight-based &amp; paediatric rules, "
        "BSA, renal adjustment, and safe dose checks",
        S("BannerNote", fontName="Helvetica", fontSize=8.5,
          textColor=colors.HexColor("#93C5FD"), alignment=TA_CENTER))

    data = [[ [title_para, Spacer(1, 4), sub_para, Spacer(1, 6), note_para] ]]
    t = Table(data, colWidths=[col_w])
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), NAVY),
        ("TOPPADDING",    (0,0), (-1,-1), 16),
        ("BOTTOMPADDING", (0,0), (-1,-1), 16),
        ("LEFTPADDING",   (0,0), (-1,-1), 16),
        ("RIGHTPADDING",  (0,0), (-1,-1), 16),
        ("ROUNDEDCORNERS", [6, 6, 6, 6]),
    ]))
    return t


def build_units_table():
    """Metric conversion quick-ref table."""
    headers = ["Unit", "Equivalent", "Unit", "Equivalent"]
    rows = [
        ["1 microgram (mcg)", "0.001 mg", "1 teaspoon (tsp)", "5 mL"],
        ["1 milligram (mg)", "1,000 mcg / 0.001 g", "1 tablespoon (tbsp)", "15 mL"],
        ["1 gram (g)", "1,000 mg", "1 fluid ounce", "30 mL"],
        ["1 kilogram (kg)", "1,000 g / 2.2 lbs", "1 cup", "240 mL"],
    ]
    table_data = [
        [Paragraph(h, TABLE_HEADER) for h in headers]
    ] + [
        [Paragraph(cell, TABLE_CELL) for cell in row] for row in rows
    ]
    col_widths = [(PAGE_W - 2*MARGIN)/4] * 4
    t = Table(table_data, colWidths=col_widths)
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,0), NAVY),
        ("BACKGROUND",    (0,1), (-1,-1), GREY_LIGHT),
        ("ROWBACKGROUNDS",(0,1), (-1,-1), [WHITE, GREY_LIGHT]),
        ("GRID",          (0,0), (-1,-1), 0.4, colors.HexColor("#D1D5DB")),
        ("TOPPADDING",    (0,0), (-1,-1), 4),
        ("BOTTOMPADDING", (0,0), (-1,-1), 4),
        ("LEFTPADDING",   (0,0), (-1,-1), 6),
    ]))
    return t


def build_summary_table():
    """Quick summary table of all formulas."""
    headers = ["Formula", "Used For", "Key Variables"]
    rows = [
        ["D/H × V",              "Oral & parenteral dose",      "Desired, Have, Vehicle"],
        ["Ratio & Proportion",   "Tablet/capsule dose",         "Cross-multiply for X"],
        ["Drip rate (gtt/min)",  "IV gravity infusion",         "Volume, Drop factor, Time"],
        ["Flow rate (mL/hr)",    "IV pump programming",         "Volume ÷ Time"],
        ["mg/kg",                "Weight-based dosing",         "Dose × Weight (kg)"],
        ["mcg/kg/min",           "Vasoactive IV drips",         "Conc., Weight, Dose"],
        ["Reconstitution",       "Powder vials",                "Desired ÷ Reconst. conc."],
        ["BSA (Mosteller)",      "Chemo & high-risk drugs",     "Height (cm) × Weight (kg)"],
        ["Cockcroft-Gault",      "Renal dose adjustment",       "Age, Weight, Creatinine"],
        ["Young's Rule",         "Paediatric 2-12 yrs",         "Age ÷ (Age + 12) × Adult"],
        ["Fried's Rule",         "Infants < 2 yrs",             "Months ÷ 150 × Adult"],
        ["Clark's Rule",         "Paediatric (lbs)",            "Weight(lb) ÷ 150 × Adult"],
        ["BSA Paediatric",       "Paediatric chemo doses",      "Child BSA ÷ 1.7 × Adult"],
        ["Safe Dose Range",      "Paediatric safety check",     "mg/kg range × Weight"],
    ]
    col_widths = [
        (PAGE_W - 2*MARGIN) * 0.27,
        (PAGE_W - 2*MARGIN) * 0.38,
        (PAGE_W - 2*MARGIN) * 0.35,
    ]
    table_data = [
        [Paragraph(h, TABLE_HEADER) for h in headers]
    ] + [
        [Paragraph(cell, TABLE_CELL) for cell in row] for row in rows
    ]
    t = Table(table_data, colWidths=col_widths, repeatRows=1)
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,0), NAVY),
        ("ROWBACKGROUNDS",(0,1), (-1,-1), [WHITE, GREY_LIGHT]),
        ("GRID",          (0,0), (-1,-1), 0.4, colors.HexColor("#D1D5DB")),
        ("TOPPADDING",    (0,0), (-1,-1), 3),
        ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ("LEFTPADDING",   (0,0), (-1,-1), 5),
    ]))
    return t


def P(text, style=None):
    if style is None:
        style = BODY
    return Paragraph(text, style)


def build_story():
    story = []
    SP = lambda h=4: Spacer(1, h)
    HR = lambda: HRFlowable(width="100%", thickness=0.5, color=colors.HexColor("#E5E7EB"), spaceAfter=3, spaceBefore=3)

    # ── Title Banner ───────────────────────────────────────────────
    story.append(build_title_block())
    story.append(SP(10))

    # ── Unit Conversions ───────────────────────────────────────────
    story.append(section_bar("  UNIT CONVERSIONS  (Essential Foundation)", color=GREY_DARK))
    story.append(SP(4))
    story.append(build_units_table())
    story.append(SP(10))

    # ════════════════════════════════════════════════════════════════
    # SECTION A: ADULT / GENERAL FORMULAS
    # ════════════════════════════════════════════════════════════════
    story.append(section_bar("  SECTION A: GENERAL / ADULT DRUG CALCULATION FORMULAS", color=TEAL))
    story.append(SP(5))

    # 1. D/H x V
    story.append(KeepTogether([
        formula_card(
            "1.  Basic Dose Formula  (D / H × V)",
            [
                "Dose to give = (Desired dose ÷ Have on hand) × Vehicle",
                "D = Desired (ordered)  |  H = Have (on hand)  |  V = Vehicle (mL, tablet)",
            ],
            [
                "<b>Ex 1 – Oral liquid:</b>  Order: Paracetamol 500 mg  |  On hand: 250 mg / 5 mL",
                "= (500 ÷ 250) × 5 mL  =  2 × 5  =  <b>10 mL</b>",
                "<b>Ex 2 – Tablets:</b>  Order: Digoxin 0.25 mg  |  On hand: 0.125 mg / tablet",
                "= (0.25 ÷ 0.125) × 1  =  <b>2 tablets</b>",
            ],
            bg_color=TEAL_LIGHT, accent=TEAL
        ),
        SP(5),
    ]))

    # 2. Ratio & Proportion
    story.append(KeepTogether([
        formula_card(
            "2.  Ratio &amp; Proportion Method",
            [
                "H : V  =  D : X     →     X = (D × V) ÷ H",
            ],
            [
                "<b>Ex:</b>  Order: Erythromycin 750 mg  |  On hand: 250 mg capsules",
                "250 : 1  =  750 : X     →     250X = 750     →     <b>X = 3 capsules</b>",
            ],
            bg_color=TEAL_LIGHT, accent=TEAL
        ),
        SP(5),
    ]))

    # 3 & 4 side by side – IV Drip Rate & Flow Rate
    left_3 = [
        P("3.  IV Drip Rate  (gtt/min)", FORMULA_NAME),
        P("gtt/min = (Volume mL × Drop factor) ÷ Time (min)", FORMULA_BOX),
        P("Drop factors:  Macro = 10/15/20 gtt/mL  |  Micro = 60 gtt/mL", NOTE),
        P("Example:", EXAMPLE_LABEL),
        P("1000 mL NS over 8 h, tubing 20 gtt/mL", EXAMPLE_TEXT),
        P("= (1000 × 20) ÷ (8 × 60) = 20,000 ÷ 480 = <b>42 gtt/min</b>", EXAMPLE_TEXT),
    ]
    right_4 = [
        P("4.  IV Flow Rate  (mL/hr)", FORMULA_NAME),
        P("Flow rate (mL/hr) = Total volume (mL) ÷ Time (hr)", FORMULA_BOX),
        P("&#8203;", NOTE),  # spacer note
        P("Example:", EXAMPLE_LABEL),
        P("500 mL D5W over 4 hours", EXAMPLE_TEXT),
        P("= 500 ÷ 4 = <b>125 mL/hr</b>", EXAMPLE_TEXT),
    ]
    story.append(KeepTogether([two_col_cards(left_3, right_4), SP(5)]))

    # 5. Infusion Time
    story.append(KeepTogether([
        formula_card(
            "5.  Infusion Time",
            ["Infusion time (hr) = Total volume (mL) ÷ Flow rate (mL/hr)"],
            [
                "<b>Ex:</b>  1000 mL infusing at 125 mL/hr",
                "= 1000 ÷ 125 = <b>8 hours</b>",
            ],
            bg_color=TEAL_LIGHT, accent=TEAL
        ),
        SP(5),
    ]))

    # 6. Weight-based mg/kg
    story.append(KeepTogether([
        formula_card(
            "6.  Weight-Based Dosing  (mg/kg)",
            ["Dose = Ordered dose (mg/kg) × Patient weight (kg)"],
            [
                "<b>Ex:</b>  Amoxicillin 25 mg/kg  |  Patient: 70 kg",
                "= 25 × 70 = <b>1,750 mg per dose</b>",
            ],
            bg_color=TEAL_LIGHT, accent=TEAL
        ),
        SP(5),
    ]))

    # 7. Weight-based IV (mcg/kg/min)
    story.append(KeepTogether([
        formula_card(
            "7.  Weight-Based IV Infusion Rate  (mcg/kg/min)",
            [
                "mL/hr = (Dose mcg/kg/min × Weight kg × 60) ÷ Concentration mcg/mL",
            ],
            [
                "<b>Ex:</b>  Dopamine 5 mcg/kg/min  |  Patient: 80 kg  |  Bag: 400 mg in 250 mL",
                "Concentration = 400,000 mcg ÷ 250 mL = 1,600 mcg/mL",
                "= (5 × 80 × 60) ÷ 1,600 = 24,000 ÷ 1,600 = <b>15 mL/hr</b>",
            ],
            note="Always double-check concentration of bag before calculating.",
            bg_color=AMBER_LIGHT, accent=AMBER
        ),
        SP(5),
    ]))

    # 8. Reconstitution
    story.append(KeepTogether([
        formula_card(
            "8.  Reconstitution Formula",
            [
                "Amount to give (mL) = Desired dose ÷ Concentration after reconstitution",
                "Concentration after reconstitution = Total drug (mg) ÷ Total volume (mL)",
            ],
            [
                "<b>Ex:</b>  Order: Ampicillin 500 mg IV  |  Vial: 1 g powder + 10 mL diluent = 100 mg/mL",
                "= 500 ÷ 100 = <b>5 mL</b>",
            ],
            bg_color=TEAL_LIGHT, accent=TEAL
        ),
        SP(5),
    ]))

    # 9 & 10 side by side – Percent solution & Units
    left_9 = [
        P("9.  Percent Solution", FORMULA_NAME),
        P("% = (Drug in g ÷ Total volume in mL) × 100", FORMULA_BOX),
        P("Example:", EXAMPLE_LABEL),
        P("10 g glucose in 100 mL  →  <b>10% solution</b>", EXAMPLE_TEXT),
    ]
    right_10 = [
        P("10.  Units-Based Dosing  (Insulin / Heparin)", FORMULA_NAME),
        P("Volume (mL) = Units ordered ÷ Units per mL", FORMULA_BOX),
        P("Example:", EXAMPLE_LABEL),
        P("Heparin 5,000 units SC  |  Available: 10,000 units/mL", EXAMPLE_TEXT),
        P("= 5,000 ÷ 10,000 = <b>0.5 mL</b>", EXAMPLE_TEXT),
    ]
    story.append(KeepTogether([two_col_cards(left_9, right_10), SP(5)]))

    # 11. BSA Mosteller
    story.append(KeepTogether([
        formula_card(
            "11.  Body Surface Area – Mosteller Formula",
            [
                "BSA (m²) = √ [ Height (cm) × Weight (kg) ÷ 3,600 ]",
            ],
            [
                "<b>Ex:</b>  Patient: 170 cm, 70 kg",
                "= √ (170 × 70 ÷ 3,600) = √ 3.306 = <b>1.82 m²</b>",
            ],
            note="Valid for both adults and children. Use on any calculator with a √ function.",
            bg_color=PURPLE_LIGHT, accent=PURPLE
        ),
        SP(5),
    ]))

    # 12. BSA-based dose
    story.append(KeepTogether([
        formula_card(
            "12.  BSA-Based Dose  (Chemotherapy / High-Risk Drugs)",
            ["Dose = BSA (m²) × Prescribed dose per m²"],
            [
                "<b>Ex:</b>  Chemo drug 50 mg/m²  |  BSA: 1.82 m²",
                "= 1.82 × 50 = <b>91 mg</b>",
            ],
            bg_color=PURPLE_LIGHT, accent=PURPLE
        ),
        SP(5),
    ]))

    # 13. Cockcroft-Gault
    story.append(KeepTogether([
        formula_card(
            "13.  Creatinine Clearance – Cockcroft-Gault  (Renal Dose Adjustment)",
            [
                "CrCl (mL/min) = [ (140 − Age) × Weight (kg) ] ÷ [ 72 × Serum Creatinine (mg/dL) ]",
                "Multiply result by <b>0.85 for females</b>",
            ],
            [
                "<b>Ex:</b>  65-year-old male, 70 kg, Cr 1.2 mg/dL",
                "= (140 − 65) × 70 ÷ (72 × 1.2)  =  75 × 70 ÷ 86.4  =  5,250 ÷ 86.4 = <b>60.8 mL/min</b>",
            ],
            note="Use actual body weight unless patient is obese — then use ideal body weight.",
            bg_color=AMBER_LIGHT, accent=AMBER
        ),
        SP(8),
    ]))

    # ════════════════════════════════════════════════════════════════
    # SECTION B: PAEDIATRIC
    # ════════════════════════════════════════════════════════════════
    story.append(section_bar("  SECTION B: PAEDIATRIC DRUG CALCULATION FORMULAS", color=GREEN))
    story.append(SP(4))
    story.append(P(
        "&#9654; Weight-based dosing (mg/kg) is the gold standard for paediatrics. "
        "Age-based rules (Young's, Fried's, Clark's) are <b>estimates only</b> and should be used "
        "only when the mg/kg dose is not known.",
        S("PaedNote", fontName="Helvetica-Oblique", fontSize=8.5,
          textColor=GREEN, leftIndent=4, spaceAfter=6, spaceBefore=2)
    ))

    # 14. mg/kg paediatric
    story.append(KeepTogether([
        formula_card(
            "14.  Weight-Based Dose  (mg/kg) — Preferred Paediatric Method",
            ["Child's dose = Ordered dose (mg/kg) × Child's weight (kg)"],
            [
                "<b>Ex:</b>  Order: Paracetamol 15 mg/kg  |  Child: 20 kg",
                "= 15 × 20 = <b>300 mg</b>",
            ],
            note="Always verify the calculated dose against the published safe dose range.",
            bg_color=GREEN_LIGHT, accent=GREEN
        ),
        SP(5),
    ]))

    # 15. Young's Rule
    story.append(KeepTogether([
        formula_card(
            "15.  Young's Rule  (Children 2 – 12 years)",
            ["Child's dose = [ Age (years) ÷ (Age + 12) ] × Adult dose"],
            [
                "<b>Ex:</b>  10-year-old child  |  Adult Paracetamol dose: 500 mg",
                "= [ 10 ÷ (10 + 12) ] × 500  =  (10 ÷ 22) × 500  =  0.455 × 500 = <b>227.5 mg</b>",
            ],
            bg_color=GREEN_LIGHT, accent=GREEN
        ),
        SP(5),
    ]))

    # 16 & 17 side by side – Fried's & Clark's
    left_16 = [
        P("16.  Fried's Rule  (Infants &lt; 2 years)", FORMULA_NAME),
        P("Child's dose = (Age in months ÷ 150) × Adult dose", FORMULA_BOX),
        P("Example:", EXAMPLE_LABEL),
        P("2-year-old (24 months)  |  Adult dose: 500 mg", EXAMPLE_TEXT),
        P("= (24 ÷ 150) × 500 = 0.16 × 500 = <b>80 mg</b>", EXAMPLE_TEXT),
    ]
    right_17 = [
        P("17.  Clark's Rule  (Weight in POUNDS)", FORMULA_NAME),
        P("Child's dose = (Weight lb ÷ 150) × Adult dose", FORMULA_BOX),
        P("&#9888; Use lbs ONLY — never kg for this rule.", NOTE),
        P("Example:", EXAMPLE_LABEL),
        P("Child: 60 lbs  |  Adult Amoxicillin dose: 500 mg", EXAMPLE_TEXT),
        P("= (60 ÷ 150) × 500 = 0.4 × 500 = <b>200 mg</b>", EXAMPLE_TEXT),
    ]
    story.append(KeepTogether([two_col_cards(left_16, right_17, bg=GREEN_LIGHT, accent=GREEN), SP(5)]))

    # 18. BSA Paediatric
    story.append(KeepTogether([
        formula_card(
            "18.  BSA-Based Paediatric Dose  (West Nomogram / Mosteller)",
            [
                "Child's dose = (Child's BSA m² ÷ 1.7 m²) × Adult dose",
                "BSA (m²) = √ [ Height (cm) × Weight (kg) ÷ 3,600 ]     ← Mosteller",
                "Average adult BSA = 1.7 m²",
            ],
            [
                "<b>Ex:</b>  Child: 100 cm, 16.4 kg  →  BSA = √(100 × 16.4 ÷ 3,600) = √0.456 = <b>0.675 m²</b>",
                "Adult dose: 500 mg   →   Child's dose = (0.675 ÷ 1.7) × 500 = 0.397 × 500 = <b>198.5 mg</b>",
            ],
            note="West Nomogram: plot height (left) and weight (right) — read BSA from SA column.",
            bg_color=GREEN_LIGHT, accent=GREEN
        ),
        SP(5),
    ]))

    # 19. Paediatric IV drip
    story.append(KeepTogether([
        formula_card(
            "19.  Paediatric IV Drip Rate",
            [
                "gtt/min = (Volume mL × Drop factor) ÷ Time (min)",
                "Paediatric sets typically use micro-drip: 60 gtt/mL",
            ],
            [
                "<b>Ex:</b>  100 mL over 4 hours, micro-drip (60 gtt/mL)",
                "= (100 × 60) ÷ (4 × 60) = 6,000 ÷ 240 = <b>25 gtt/min</b>",
            ],
            bg_color=GREEN_LIGHT, accent=GREEN
        ),
        SP(5),
    ]))

    # 20. Safe Dose Range
    story.append(KeepTogether([
        formula_card(
            "20.  Safe Dose Range Check  (Paediatric Safety — ALWAYS Perform)",
            [
                "Low safe dose  = Low mg/kg × Child's weight (kg)",
                "High safe dose = High mg/kg × Child's weight (kg)",
                "Prescribed dose MUST fall within this range before administration",
            ],
            [
                "<b>Ex:</b>  Safe range: 10–30 mg/kg  |  Child: 20 kg",
                "Low = 10 × 20 = 200 mg    |    High = 30 × 20 = 600 mg",
                "Prescribed dose must be between <b>200 mg and 600 mg</b> ✓",
            ],
            note="If the prescribed dose is outside the safe range, clarify with the prescriber before administering.",
            bg_color=RED_LIGHT, accent=RED
        ),
        SP(8),
    ]))

    # ── Quick Summary Table ────────────────────────────────────────
    story.append(section_bar("  QUICK SUMMARY: ALL FORMULAS AT A GLANCE", color=NAVY))
    story.append(SP(5))
    story.append(build_summary_table())
    story.append(SP(8))

    # ── Clinical Reminders ─────────────────────────────────────────
    story.append(section_bar("  KEY CLINICAL REMINDERS", color=RED))
    story.append(SP(4))

    reminders = [
        ("&#9888; Units first",   "Always confirm mg vs mcg vs g before calculating. A ×1000 error is fatal."),
        ("&#9888; Double-check",  "High-alert drugs (insulin, heparin, opioids, chemo) must have a second nurse verify independently."),
        ("&#9656; Paediatric",    "mg/kg is the gold standard. Age-based rules (Young's, Fried's, Clark's) are estimates only."),
        ("&#9656; Renal patients","Use Cockcroft-Gault CrCl to adjust renally-cleared drugs. Elderly patients require extra caution."),
        ("&#9656; Weight",        "1 kg = 2.2 lbs. Convert lbs → kg by dividing by 2.2. Never mix units."),
        ("&#9656; IV bags",       "Always recalculate concentration when a different bag size is dispensed."),
        ("&#9656; BSA drugs",     "Recalculate BSA if patient's weight changes significantly during treatment."),
    ]
    for icon_label, text in reminders:
        data = [[
            Paragraph(icon_label, S("RL", fontName="Helvetica-Bold", fontSize=8.5, textColor=RED)),
            Paragraph(text, S("RT", fontName="Helvetica", fontSize=8.5, textColor=GREY_DARK)),
        ]]
        t = Table(data, colWidths=[3.5*cm, PAGE_W - 2*MARGIN - 3.5*cm])
        t.setStyle(TableStyle([
            ("TOPPADDING",    (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
            ("LEFTPADDING",   (0,0), (0,-1), 8),
            ("VALIGN",        (0,0), (-1,-1), "TOP"),
        ]))
        story.append(t)

    story.append(SP(6))
    story.append(HR())
    story.append(P(
        "This pocket guide is for educational and clinical reference only. "
        "Always verify drug doses against current national formularies, "
        "local protocols, and prescriber orders. Clinical judgment is essential.",
        S("Disc", fontName="Helvetica-Oblique", fontSize=7.5,
          textColor=GREY_MID, alignment=TA_CENTER, spaceAfter=4)
    ))

    return story


# ── Generate PDF ───────────────────────────────────────────────────
output_path = "/home/daytona/workspace/drug-calc-guide/Drug_Calculation_Pocket_Guide.pdf"
doc = DrugCalcDoc(output_path)
story = build_story()
doc.build(story)
print(f"PDF generated: {output_path}")

Running Command

cd /home/daytona/workspace/drug-calc-guide && python generate_guide.py 2>&1

Editing File

~/drug-calc-guide/generate_guide.py

Successfully replaced 1 instance(s) of the string in '/home/daytona/workspace/drug-calc-guide/generate_guide.py'

Running Command

cd /home/daytona/workspace/drug-calc-guide && python generate_guide.py 2>&1

Running Command

ls -lh /home/daytona/workspace/drug-calc-guide/Drug_Calculation_Pocket_Guide.pdf

Your Drug Calculation Pocket Guide PDF is ready to download:

Drug Calculation Pocket Guide

PDF Document · PDF

What's inside the guide (A4, print-ready):

Title banner with guide description
Unit Conversion table - metric, household, apothecary equivalents
Section A - Adult/General Formulas (13 formulas):
- D/H × V basic dose formula
- Ratio & Proportion method
- IV Drip Rate (gtt/min) & Flow Rate (mL/hr) - shown side by side
- Infusion Time
- Weight-based mg/kg dosing
- Weight-based IV drip (mcg/kg/min) for vasoactive drugs
- Reconstitution formula
- Percent solution & Units-based dosing (side by side)
- BSA - Mosteller formula
- BSA-based dose (chemo)
- Cockcroft-Gault for renal adjustment
Section B - Paediatric Formulas (7 formulas):
- mg/kg (gold standard)
- Young's Rule (2-12 yrs)
- Fried's Rule (infants <2 yrs) & Clark's Rule (lbs) - side by side
- BSA-based paediatric dose
- Paediatric IV drip rate
- Safe Dose Range check
Quick Summary table - all 20 formulas at a glance
7 Key Clinical Reminders - units, double-checking, high-alert drugs
Footer on every page with page number and disclaimer

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