const pptxgen = require("pptxgenjs");

const pres = new pptxgen();
pres.layout = "LAYOUT_16x9";
pres.title = "Absorption and Bioavailability in Pharmacology";
pres.author = "Orris Medical";

// Color palette: deep navy dominates, teal accent, white text, gold highlights
const C = {
  navy:    "0D1B2A",
  navyMid: "1B3A5C",
  teal:    "00A896",
  tealDk:  "007A6E",
  gold:    "F4C430",
  white:   "FFFFFF",
  offwhite:"E8F0F7",
  light:   "C9DFF0",
  gray:    "8899AA",
  darkgray:"2E4057",
  red:     "E63946",
  green:   "06D6A0",
};

// ─────────────────────────────────────────────
// SLIDE 1 — TITLE
// ─────────────────────────────────────────────
{
  const s = pres.addSlide();
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  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: "100%", fill: { color: C.navy } });
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  s.addText("PHARMACOLOGY", { x: 0.5, y: 0.6, w: 9, h: 0.5, fontSize: 13, color: C.teal, bold: true, charSpacing: 8, align: "left", margin: 0 });
  s.addText("Absorption &\nBioavailability", { x: 0.5, y: 1.1, w: 9, h: 1.3, fontSize: 44, color: C.white, bold: true, align: "left", margin: 0, lineSpacingMultiple: 1.1 });
  s.addText("Mechanisms · Factors · Clinical Significance", { x: 0.5, y: 2.5, w: 9, h: 0.5, fontSize: 15, color: C.light, align: "left", margin: 0 });

  // Info boxes at bottom
  const boxes = [
    { label: "ADME", sub: "Core pharmacokinetics" },
    { label: "Routes", sub: "All major pathways" },
    { label: "First Pass", sub: "Hepatic extraction" },
    { label: "Bioequivalence", sub: "AUC & Cmax" },
  ];
  boxes.forEach((b, i) => {
    const bx = 0.5 + i * 2.42;
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    s.addText(b.label, { x: bx, y: 3.88, w: 2.2, h: 0.42, fontSize: 15, color: C.gold, bold: true, align: "center", margin: 0 });
    s.addText(b.sub, { x: bx, y: 4.3, w: 2.2, h: 0.35, fontSize: 9, color: C.light, align: "center", margin: 0 });
  });

  s.addText("Sources: Goodman & Gilman's · Katzung · Harrison's 22E", { x: 0.5, y: 5.2, w: 9, h: 0.3, fontSize: 8, color: C.gray, align: "left", margin: 0 });
}

// ─────────────────────────────────────────────
// SLIDE 2 — WHAT IS ABSORPTION?
// ─────────────────────────────────────────────
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  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: 1.05, fill: { color: C.navyMid } });
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  s.addText("ABSORPTION", { x: 0.4, y: 0.1, w: 9.2, h: 0.38, fontSize: 22, color: C.white, bold: true, align: "left", margin: 0 });
  s.addText("Movement of a drug from its site of administration into the systemic circulation", { x: 0.4, y: 0.55, w: 9.2, h: 0.42, fontSize: 12, color: C.light, align: "left", margin: 0 });

  // Definition box
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  s.addText([
    { text: "Definition: ", options: { bold: true, color: C.gold } },
    { text: "Absorption is the movement of a drug from its site of administration into the central compartment (bloodstream). For solid dosage forms, absorption first requires dissolution of the tablet or capsule, liberating the drug.", options: { color: C.white } }
  ], { x: 0.5, y: 1.3, w: 9, h: 0.75, fontSize: 11.5, align: "left", margin: 0 });

  // Key factors
  s.addText("Key Factors Governing Absorption", { x: 0.4, y: 2.25, w: 9.2, h: 0.38, fontSize: 15, color: C.navyMid, bold: true, margin: 0 });

  const factors = [
    { icon: "💊", title: "Dosage Form", desc: "Dissolution of tablet/capsule must occur first" },
    { icon: "🔬", title: "Physicochemical Properties", desc: "Lipid solubility, molecular weight, ionization state" },
    { icon: "🧬", title: "Membrane Permeability", desc: "Passive diffusion vs active transport" },
    { icon: "🩸", title: "Blood Flow", desc: "Blood supply to absorption site affects rate" },
    { icon: "📐", title: "Surface Area", desc: "GI tract has large SA favoring absorption" },
    { icon: "⚗️", title: "Drug Concentration", desc: "Higher concentration → faster passive diffusion" },
  ];

  factors.forEach((f, i) => {
    const col = i % 3;
    const row = Math.floor(i / 3);
    const bx = 0.4 + col * 3.12;
    const by = 2.75 + row * 1.2;
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  });
}

// ─────────────────────────────────────────────
// SLIDE 3 — MEMBRANE PASSAGE MECHANISMS
// ─────────────────────────────────────────────
{
  const s = pres.addSlide();
  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: "100%", fill: { color: C.navy } });
  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: 1.05, fill: { color: C.tealDk } });

  s.addText("MECHANISMS OF MEMBRANE PASSAGE", { x: 0.4, y: 0.12, w: 9.2, h: 0.42, fontSize: 20, color: C.white, bold: true, margin: 0 });
  s.addText("Drug transport across biological membranes determines absorption rate and extent", { x: 0.4, y: 0.6, w: 9.2, h: 0.38, fontSize: 11, color: C.light, margin: 0 });

  const mechs = [
    {
      title: "1. Passive Diffusion",
      color: C.teal,
      points: [
        "Most common mechanism",
        "Drug moves high → low concentration gradient",
        "Nonionized, lipophilic forms cross better",
        "Rate ∝ concentration gradient × lipid solubility",
        "pH-Partition hypothesis applies",
      ]
    },
    {
      title: "2. Active Transport",
      color: C.gold,
      points: [
        "Carrier-mediated; requires energy (ATP)",
        "Can move drugs against concentration gradient",
        "Saturable and inhibitable",
        "Examples: P-glycoprotein, OATP, OAT transporters",
        "Subject to drug-drug interactions",
      ]
    },
    {
      title: "3. Facilitated Diffusion",
      color: C.green,
      points: [
        "Carrier-mediated but NO energy required",
        "Moves drug down concentration gradient",
        "Faster than simple passive diffusion",
        "Also saturable",
        "Examples: glucose transporters (GLUT family)",
      ]
    },
    {
      title: "4. Pinocytosis / Endocytosis",
      color: C.red,
      points: [
        "Cell engulfs macromolecules in vesicles",
        "Important for large molecules (proteins, vaccines)",
        "Used by some peptide drugs",
        "Not relevant for most small-molecule drugs",
        "",
      ]
    },
  ];

  mechs.forEach((m, i) => {
    const col = i % 2;
    const row = Math.floor(i / 2);
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    s.addText(m.title, { x: bx + 0.1, y: by + 0.04, w: 4.35, h: 0.3, fontSize: 12, color: C.navy, bold: true, margin: 0 });
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      text: p,
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  });
}

// ─────────────────────────────────────────────
// SLIDE 4 — pH PARTITION & IONIZATION
// ─────────────────────────────────────────────
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  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: "100%", fill: { color: C.offwhite } });
  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: 1.05, fill: { color: C.navy } });
  s.addShape(pres.ShapeType.rect, { x: 0, y: 1.05, w: "100%", h: 0.06, fill: { color: C.gold } });

  s.addText("pH PARTITION HYPOTHESIS & IONIZATION", { x: 0.4, y: 0.12, w: 9.2, h: 0.42, fontSize: 20, color: C.white, bold: true, margin: 0 });
  s.addText("Only the nonionized (lipophilic) form of a drug crosses biological membranes effectively", { x: 0.4, y: 0.6, w: 9.2, h: 0.38, fontSize: 11, color: C.light, margin: 0 });

  // Henderson-Hasselbalch box
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  s.addText("Henderson-Hasselbalch Equation", { x: 0.55, y: 1.27, w: 9, h: 0.32, fontSize: 13, color: C.gold, bold: true, margin: 0 });
  s.addText("For weak acids:  pH = pKa + log([A⁻]/[HA])     →   Ionized form = A⁻  (cannot cross membrane)", { x: 0.55, y: 1.6, w: 9, h: 0.3, fontSize: 10.5, color: C.white, margin: 0 });
  s.addText("For weak bases:  pH = pKa + log([B]/[BH⁺])     →   Ionized form = BH⁺ (cannot cross membrane)", { x: 0.55, y: 1.9, w: 9, h: 0.3, fontSize: 10.5, color: C.white, margin: 0 });

  // Stomach vs Intestine table
  s.addText("Absorption Site Comparison", { x: 0.4, y: 2.5, w: 9.2, h: 0.38, fontSize: 14, color: C.navyMid, bold: true, margin: 0 });

  const rows = [
    ["Site", "pH", "Best Absorbed", "Example"],
    ["Stomach", "1 – 2", "Weak ACIDS (nonionized)", "Aspirin (pKa 3.5), Ibuprofen"],
    ["Duodenum / Jejunum", "5 – 7", "Weak BASES & most drugs", "Morphine, Codeine, Ampicillin"],
    ["Ileum / Colon", "7 – 8", "Most drugs (large SA)", "Sustained-release formulations"],
    ["Buccal / Sublingual", "~7", "Lipophilic drugs bypass FPE", "Nitroglycerine, Buprenorphine"],
  ];

  rows.forEach((row, ri) => {
    const by = 2.95 + ri * 0.49;
    const isHeader = ri === 0;
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      s.addShape(pres.ShapeType.rect, {
        x: bx, y: by, w: widths[ci], h: 0.46,
        fill: { color: isHeader ? C.navyMid : (ri % 2 === 0 ? C.white : "#EAF3FB") },
        line: { color: C.light, width: 0.5 }
      });
      s.addText(cell, {
        x: bx + 0.05, y: by + 0.05, w: widths[ci] - 0.1, h: 0.36,
        fontSize: isHeader ? 10 : 9.5,
        color: isHeader ? C.gold : C.darkgray,
        bold: isHeader,
        align: "left", margin: 0
      });
    });
  });
}

// ─────────────────────────────────────────────
// SLIDE 5 — BIOAVAILABILITY DEFINED
// ─────────────────────────────────────────────
{
  const s = pres.addSlide();
  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: "100%", fill: { color: C.navy } });
  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: 0.2, h: "100%", fill: { color: C.gold } });
  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: 1.05, fill: { color: C.darkgray } });

  s.addText("BIOAVAILABILITY (F)", { x: 0.4, y: 0.12, w: 9.2, h: 0.42, fontSize: 22, color: C.gold, bold: true, margin: 0 });
  s.addText("The fraction of an administered dose that reaches the systemic circulation unchanged", { x: 0.4, y: 0.62, w: 9.2, h: 0.35, fontSize: 11.5, color: C.light, margin: 0 });

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  s.addText("F = AUCoral / AUCIV   ×  (Dose IV / Dose oral)", { x: 2.0, y: 1.22, w: 6.0, h: 0.48, fontSize: 16, color: C.teal, bold: true, align: "center", margin: 0 });
  s.addText("where 0 < F ≤ 1   (IV route: F = 1 by definition)", { x: 2.0, y: 1.72, w: 6.0, h: 0.34, fontSize: 10.5, color: C.gold, align: "center", margin: 0 });

  // Two reasons for low F
  s.addText("Two Main Reasons for Reduced Bioavailability", { x: 0.4, y: 2.55, w: 9.2, h: 0.4, fontSize: 14, color: C.teal, bold: true, margin: 0 });

  const reasons = [
    {
      num: "1",
      title: "Incomplete Absorption",
      color: C.red,
      points: [
        "Poor drug solubility in GI fluids",
        "Unstable at gastric pH (e.g., penicillin G)",
        "Large molecular size limits membrane passage",
        "Efflux transporters (P-glycoprotein) pump drug back",
        "Incomplete dissolution from solid forms",
      ]
    },
    {
      num: "2",
      title: "Pre-systemic (First-Pass) Elimination",
      color: C.gold,
      points: [
        "Intestinal wall metabolism (CYP3A4, MAO)",
        "Hepatic metabolism before reaching systemic circulation",
        "Biliary excretion of absorbed drug",
        "Example: morphine F ≈ 33% (hepatic ER = 0.67)",
        "Example: lidocaine — NOT given orally (extensive FPE)",
      ]
    }
  ];

  reasons.forEach((r, i) => {
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    s.addShape(pres.ShapeType.rect, { x: bx, y: 3.05, w: 4.65, h: 0.44, fill: { color: r.color } });
    s.addText(r.num + ".  " + r.title, { x: bx + 0.1, y: 3.08, w: 4.45, h: 0.38, fontSize: 12, color: C.navy, bold: true, margin: 0 });
    const pts = r.points.map((p, j) => ({ text: p, options: { bullet: true, breakLine: j < r.points.length - 1, color: C.offwhite } }));
    s.addText(pts, { x: bx + 0.15, y: 3.56, w: 4.4, h: 1.85, fontSize: 9.5, margin: 0, lineSpacingMultiple: 1.2 });
  });
}

// ─────────────────────────────────────────────
// SLIDE 6 — FIRST-PASS EFFECT
// ─────────────────────────────────────────────
{
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  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: 1.05, fill: { color: C.red } });

  s.addText("FIRST-PASS EFFECT (Pre-systemic Elimination)", { x: 0.4, y: 0.1, w: 9.2, h: 0.44, fontSize: 20, color: C.white, bold: true, margin: 0 });
  s.addText("Oral drugs must traverse intestinal epithelium → portal vein → liver before reaching systemic circulation", { x: 0.4, y: 0.62, w: 9.2, h: 0.36, fontSize: 11, color: C.white, margin: 0 });

  // Pathway flow
  const steps = [
    { label: "Oral\nDose", color: C.navyMid },
    { label: "GI\nLumen", color: C.darkgray },
    { label: "Enterocyte\n(intestinal wall)", color: C.tealDk },
    { label: "Portal\nVein", color: C.navyMid },
    { label: "Liver\n(hepatocyte)", color: C.red },
    { label: "Systemic\nCirculation", color: C.teal },
  ];

  steps.forEach((st, i) => {
    const bx = 0.25 + i * 1.63;
    s.addShape(pres.ShapeType.roundRect, { x: bx, y: 1.15, w: 1.42, h: 0.8, fill: { color: st.color }, rectRadius: 0.08 });
    s.addText(st.label, { x: bx, y: 1.17, w: 1.42, h: 0.76, fontSize: 9, color: C.white, bold: true, align: "center", margin: 0 });
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      s.addShape(pres.ShapeType.rect, { x: bx + 1.42, y: 1.47, w: 0.21, h: 0.18, fill: { color: C.gray } });
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  // Metabolism sites info
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  const sites = [
    { site: "Intestinal Wall", enzymes: "CYP3A4 (most abundant gut CYP)\nP-glycoprotein efflux transporter\nMoamine oxidase (MAO)", bg: "#EAF3FB" },
    { site: "Liver (Hepatocyte)", enzymes: "CYP450 enzymes (CYP3A4, CYP2D6...)\nGlucuronyl transferase, Sulfotransferase\nBiliary excretion of metabolites", bg: "#FFE8E8" },
  ];

  sites.forEach((site, i) => {
    const bx = 0.4 + i * 4.85;
    s.addShape(pres.ShapeType.roundRect, { x: bx, y: 2.55, w: 4.65, h: 1.35, fill: { color: site.bg }, line: { color: i === 0 ? C.teal : C.red, width: 1.5 }, rectRadius: 0.1 });
    s.addText(site.site, { x: bx + 0.1, y: 2.6, w: 4.45, h: 0.34, fontSize: 13, color: C.navyMid, bold: true, margin: 0 });
    s.addText(site.enzymes, { x: bx + 0.1, y: 2.97, w: 4.45, h: 0.88, fontSize: 10, color: C.darkgray, margin: 0 });
  });

  // Formula
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  s.addText("F = f  ×  (1 − ER)     where  f = fraction absorbed,  ER = hepatic extraction ratio", { x: 0.6, y: 4.1, w: 8.8, h: 0.28, fontSize: 12.5, color: C.gold, bold: true, margin: 0 });
  s.addText("Example: Morphine — f ≈ 1 (fully absorbed), ER = 0.67  →  F = 1 × (1 − 0.67) = 0.33 (33%)", { x: 0.6, y: 4.4, w: 8.8, h: 0.26, fontSize: 10.5, color: C.light, margin: 0 });

  // High extraction drugs
  s.addText("High Extraction Drugs (extensive FPE): Morphine · Lidocaine · Propranolol · Isoniazid · Verapamil · Tricyclic antidepressants", {
    x: 0.4, y: 4.82, w: 9.2, h: 0.4,
    fontSize: 9.5, color: C.darkgray, align: "center", italic: true, margin: 0
  });
}

// ─────────────────────────────────────────────
// SLIDE 7 — ROUTES OF ADMINISTRATION
// ─────────────────────────────────────────────
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  s.addShape(pres.ShapeType.rect, { x: 0, y: 0, w: "100%", h: 1.0, fill: { color: C.teal } });

  s.addText("ROUTES OF ADMINISTRATION", { x: 0.4, y: 0.1, w: 9.2, h: 0.44, fontSize: 22, color: C.navy, bold: true, margin: 0 });
  s.addText("Bioavailability varies widely depending on route; IV route = 100% reference standard", { x: 0.4, y: 0.6, w: 9.2, h: 0.34, fontSize: 11, color: C.navyMid, margin: 0 });

  // Table header
  const headers = ["Route", "Bioavail. (%)", "Onset", "First-Pass?", "Key Notes"];
  const widths = [1.7, 1.3, 0.9, 1.2, 4.3];
  const xStarts = [0.3, 2.0, 3.3, 4.2, 5.4];

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    ["Intravenous (IV)", "100 (by def.)", "Immediate", "None", "Gold standard; risk of infection, phlebitis"],
    ["Intramuscular (IM)", "75–100", "Fast", "Bypassed", "Good for poorly soluble drugs; depot formulations"],
    ["Subcutaneous (SC)", "75–100", "Moderate", "Bypassed", "Insulin, heparin, vaccines; slower than IM"],
    ["Oral (PO)", "5–<100", "Slow-mod", "Significant", "Most convenient; subject to GI & hepatic FPE"],
    ["Sublingual", "~100", "Fast", "Bypassed", "Rapid absorption; e.g., nitroglycerine, buprenorphine"],
    ["Rectal (PR)", "30–<100", "Variable", "Partial", "Less FPE than oral; useful when PO not possible"],
    ["Inhalation", "5–100", "Very fast", "Minimal", "Direct lung action; e.g., salbutamol, anaesthetics"],
    ["Transdermal", "Varies", "Slow", "Bypassed", "Sustained delivery; e.g., fentanyl, nicotine patches"],
  ];

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        x: xStarts[ci] + 0.05, y: 1.57 + ri * 0.48, w: widths[ci] - 0.1, h: 0.38,
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        color: ci === 1 ? C.gold : C.offwhite,
        bold: ci === 0,
        margin: 0
      });
    });
  });
}

// ─────────────────────────────────────────────
// SLIDE 8 — FACTORS AFFECTING BIOAVAILABILITY
// ─────────────────────────────────────────────
{
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  s.addText("FACTORS AFFECTING BIOAVAILABILITY", { x: 0.4, y: 0.1, w: 9.2, h: 0.42, fontSize: 20, color: C.white, bold: true, margin: 0 });
  s.addText("Multiple physiological, pharmaceutical, and pathological variables influence F", { x: 0.4, y: 0.62, w: 9.2, h: 0.35, fontSize: 11, color: C.light, margin: 0 });

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      title: "Pharmaceutical Factors",
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      items: ["Particle size & dissolution rate", "Formulation (salt form, prodrug)", "Excipients & binders", "Dosage form: solution > suspension > capsule > tablet"]
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    {
      title: "Patient Factors",
      icon: "🧑‍⚕️",
      color: C.gold,
      items: ["GI motility & gastric emptying time", "Splanchnic blood flow", "Gut microbiome composition (>1000 species)", "Age: neonates & elderly have altered absorption"]
    },
    {
      title: "Disease States",
      icon: "🏥",
      color: C.red,
      items: ["Malabsorption syndromes (Crohn's, celiac)", "Liver disease → reduced first-pass metabolism", "Heart failure → reduced gut blood flow", "Renal failure → altered protein binding & Vd"]
    },
    {
      title: "Drug Interactions",
      icon: "⚠️",
      color: "#9B59B6",
      items: ["Food: delays/enhances absorption (high-fat meal)", "Antacids: chelation of fluoroquinolones, tetracyclines", "P-gp inhibitors: increase bioavailability of substrates", "Enzyme inducers (rifampicin): reduce F of many drugs"]
    },
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// ─────────────────────────────────────────────
// SLIDE 9 — AUC & BIOEQUIVALENCE
// ─────────────────────────────────────────────
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  s.addText("AUC, Cmax & BIOEQUIVALENCE", { x: 0.4, y: 0.1, w: 9.2, h: 0.42, fontSize: 22, color: C.teal, bold: true, margin: 0 });
  s.addText("Pharmacokinetic metrics used to measure and compare bioavailability", { x: 0.4, y: 0.62, w: 9.2, h: 0.36, fontSize: 11.5, color: C.light, margin: 0 });

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    { name: "Cmax", full: "Peak Plasma Concentration", desc: "Maximum drug concentration achieved. Influenced by rate of absorption and dose.", color: C.gold },
    { name: "Tmax", full: "Time to Peak Concentration", desc: "Time at which Cmax is reached. Faster absorption = earlier Tmax. Related to rate, not extent.", color: C.green },
    { name: "t½", full: "Elimination Half-Life", desc: "Time to reduce concentration by 50%. Determined by Vd and clearance. Not a measure of bioavailability.", color: "#9B59B6" },
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  s.addText("Two formulations are bioequivalent when their AUC and Cmax fall within 80–125% of each other (90% CI). This is the FDA standard for generic drug approval — same active ingredient, same dose, same route, same bioavailability.", {
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    { text: "AUC measures EXTENT of absorption. Cmax & Tmax reflect RATE. Two drugs with equal AUC but different Cmax may have very different clinical effects, especially for single-dose therapy (e.g., hypnotics, analgesics).", options: { color: C.light } }
  ], { x: 0.5, y: 4.5, w: 9.1, h: 0.64, fontSize: 10, margin: 0 });
}

// ─────────────────────────────────────────────
// SLIDE 10 — CLINICAL IMPLICATIONS
// ─────────────────────────────────────────────
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  s.addText("CLINICAL IMPLICATIONS", { x: 0.4, y: 0.1, w: 9.2, h: 0.44, fontSize: 22, color: C.white, bold: true, margin: 0 });
  s.addText("How absorption & bioavailability knowledge guides prescribing decisions", { x: 0.4, y: 0.62, w: 9.2, h: 0.35, fontSize: 11, color: C.light, margin: 0 });

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    { title: "Route Selection", body: "Choose IV for immediate/precise effect (e.g., emergencies, drugs with extensive FPE like lidocaine). Oral for maintenance therapy when bioavailability is predictable.", icon: "🎯" },
    { title: "Dose Adjustment", body: "Oral doses must compensate for first-pass effect. Morphine: PO dose ~3× IV dose due to F ≈ 33%. Hepatic impairment → reduced FPE → dose reduction needed.", icon: "📊" },
    { title: "Drug Interactions", body: "Grapefruit juice inhibits CYP3A4 → increases bioavailability of statins, calcium channel blockers. Rifampicin induces CYP3A4 → dramatically reduces F of many drugs.", icon: "⚠️" },
    { title: "Formulation Design", body: "Sustained-release formulations achieve zero-order absorption. Prodrugs bypass FPE (e.g., enalapril → enalaprilat). Sublingual/transdermal bypass gut and liver entirely.", icon: "💡" },
    { title: "Special Populations", body: "Neonates: immature gut enzymes, different gastric pH. Elderly: reduced gut motility, blood flow. Liver disease: reduced first-pass, increased F of extracted drugs.", icon: "👶👴" },
    { title: "Generic Substitution", body: "Bioequivalence (80–125% AUC rule) ensures generics are clinically interchangeable. Exception: narrow therapeutic index drugs (e.g., warfarin, phenytoin) — require careful monitoring.", icon: "💊" },
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// ─────────────────────────────────────────────
// SLIDE 11 — SUMMARY / KEY TAKEAWAYS
// ─────────────────────────────────────────────
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  s.addText("KEY TAKEAWAYS", { x: 0.4, y: 0.1, w: 9.2, h: 0.44, fontSize: 24, color: C.white, bold: true, margin: 0 });
  s.addText("Absorption & Bioavailability in Pharmacology", { x: 0.4, y: 0.62, w: 9.2, h: 0.35, fontSize: 12, color: C.light, margin: 0 });

  const takeaways = [
    { num: "01", text: "Absorption = drug movement from administration site to bloodstream. Bioavailability (F) = fraction reaching systemic circulation unchanged." },
    { num: "02", text: "Oral route: most convenient but subject to FPE. IV route: 100% bioavailability, the gold standard for comparison." },
    { num: "03", text: "First-Pass Effect reduces oral bioavailability via intestinal (CYP3A4, P-gp) and hepatic metabolism before systemic circulation." },
    { num: "04", text: "F = f × (1 − ER). High-extraction drugs (morphine, propranolol) have low F. Routes bypassing the liver (SL, IV, TD) avoid FPE." },
    { num: "05", text: "AUC measures extent of absorption; Cmax and Tmax reflect rate. Bioequivalence requires AUC and Cmax within 80–125%." },
    { num: "06", text: "Factors: drug physicochemistry, dosage form, GI physiology, blood flow, enzymes, food, disease, age, and drug interactions all alter F." },
  ];

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  s.addText("Sources: Goodman & Gilman's Pharmacological Basis of Therapeutics | Katzung's Basic & Clinical Pharmacology 16e | Harrison's Principles of Internal Medicine 22e (2025)", {
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