Pantop rantidine odanseteron biscopan drotaverine metaplromide explain in easy way indications contraindications side effects dose safe dose how to give in chart form
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Pantoprazole, Ranitidine, Ondansetron, Buscopan, Drotaverine, Metoclopramide — Simple Guide
These 6 drugs are commonly given together as an "abdominal pain / vomiting cocktail" in EDs and wards (e.g., for gastroenteritis, renal colic, post-op nausea). Here's what each one actually does and how to use it safely.
Quick one-line explanation of each
| Drug | What it is | What it does in simple words |
|---|---|---|
| Pantoprazole | Proton pump inhibitor (PPI) | Switches off acid production in the stomach |
| Ranitidine | H2-receptor blocker | Reduces stomach acid (older, weaker than PPIs) |
| Ondansetron | 5-HT3 (serotonin) blocker | Stops the "vomiting signal" in the brain/gut |
| Buscopan (hyoscine butylbromide) | Anticholinergic antispasmodic | Relaxes gut/smooth muscle cramps ("colic") |
| Drotaverine | PDE4 inhibitor (musculotropic) | Relaxes smooth muscle spasm without drying mouth/eyes |
| Metoclopramide | Dopamine (D2) blocker, prokinetic | Stops vomiting AND pushes stomach contents forward |
Full comparison chart
| Parameter | Pantoprazole | Ranitidine | Ondansetron | Buscopan (Hyoscine butylbromide) | Drotaverine | Metoclopramide |
|---|---|---|---|---|---|---|
| Class | PPI | H2 blocker | 5-HT3 antagonist | Antimuscarinic antispasmodic | Selective PDE4 inhibitor, non-anticholinergic spasmolytic | Dopamine antagonist / prokinetic |
| Main indications | Acid reflux/GERD, peptic ulcer, stress ulcer prophylaxis, Zollinger-Ellison syndrome | Peptic ulcer, GERD, dyspepsia (largely replaced by PPIs) | Nausea/vomiting from chemo, radiotherapy, surgery (PONV), gastroenteritis | Abdominal colic, renal/biliary colic, IBS spasm, GI endoscopy prep | Renal colic, biliary colic, dysmenorrhea, GI spasm | Nausea/vomiting, gastroparesis, GERD, aiding gut tube placement |
| Contraindications | Hypersensitivity to PPIs; caution with clopidogrel (reduces its effect) | Hypersensitivity; reduce dose in renal impairment; withdrawn/banned in many countries since 2020 (NDMA - possible carcinogen contamination) | Congenital long QT syndrome; concurrent apomorphine; caution in electrolyte imbalance | Myasthenia gravis, glaucoma, paralytic ileus/mechanical obstruction, urinary retention, tachyarrhythmia | Severe hepatic/renal/cardiac failure, hypersensitivity, AV block, pregnancy/lactation (caution), children under 6 yrs (varies by country) | Bowel obstruction/perforation, pheochromocytoma, epilepsy, Parkinson disease, children <1 yr |
| Common side effects | Headache, diarrhea, abdominal pain; long-term - low B12/Mg, fracture risk, C. diff risk | Headache, dizziness, constipation; rare confusion in elderly, bradycardia if pushed fast IV | Headache, constipation, transient flushing, QT prolongation (dose-dependent) | Dry mouth, blurred vision, tachycardia, urinary retention, constipation | Dizziness, hypotension if given fast IV, headache, nausea | Drowsiness, restlessness, extrapyramidal symptoms/dystonia (especially young females), tardive dyskinesia with prolonged use |
| Adult dose | 40 mg IV/PO OD (up to BD in severe cases) | 50 mg IV q6-8h, or 150 mg PO BD | 4-8 mg IV/IM/PO, may repeat; max single IV dose 16 mg (FDA advisory due to QT risk) | 20 mg IV/IM/PO, repeat q6-8h; max 100 mg/day | 40-80 mg IV/IM slow, or PO 40-80 mg 2-3 times/day; max ~240 mg/day | 10 mg IV/IM/PO TID; max 30 mg/day (0.5 mg/kg/day) |
| Safe pediatric dose | 1 mg/kg/day (specialist guidance advised) | 2-4 mg/kg/day divided (limited use now given safety concerns) | 0.1-0.15 mg/kg/dose (max per protocol) | Not usually <6 months; weight-based dosing under supervision | Avoid in young children unless local guideline supports weight-based dosing | AVOID routine use — high dystonia risk in children; if used, 0.1-0.15 mg/kg, max 3 days |
| How to give (IV) | Dilute in NS, give slow IV push over 2 min or infuse over 15 min | Dilute in NS/D5, give slow IV over 2 min or infuse over 15-20 min (never rapid push - can cause bradycardia/hypotension) | Dilute in 20-50 mL NS, infuse over 15 min OR slow IV push over ≥30 sec-2 min | Give slow IV/IM push undiluted or diluted in small NS volume over 1-2 min | Give slow IV/IM over 2-3 min (rapid push can cause hypotension/flushing) | Slow IV push over 1-2 min or short infusion; rapid push can cause anxiety/akathisia |
Key safety points to remember
- Ranitidine: Many regulators (US FDA, and others) pulled ranitidine off the market in 2020 because of NDMA (a probable carcinogen) contamination found in various batches. In current practice it has largely been replaced by PPIs (like pantoprazole) or famotidine. If it's still available in your setting, it should generally not be first choice long-term.
- Metoclopramide: Carries a boxed warning for tardive dyskinesia with prolonged/high-dose use — most guidelines limit continuous use to a maximum of 5 days. Avoid in children under 1 year and use cautiously in young women (highest dystonia risk).
- Ondansetron: Watch the ECG/QT interval in patients with electrolyte problems or on other QT-prolonging drugs; don't exceed the single IV dose limit.
- Buscopan: Never give to patients with suspected bowel obstruction, glaucoma, or myasthenia gravis — it can worsen these conditions significantly.
- Drotaverine: Not approved by the US FDA (not marketed in the US); it's widely used in India, Eastern Europe, and parts of Asia. Give slowly IV to avoid a drop in blood pressure.
- Combining drugs: When several of these are given together (a common "GI cocktail" for colic/vomiting), give each one as a separate slow IV push or mini-infusion, not all mixed in one syringe, and always check for cumulative sedation/hypotension risk, especially in elderly or cardiac patients.
Sources: Katzung's Basic and Clinical Pharmacology 16e; Goodman & Gilman's Pharmacological Basis of Therapeutics; Yamada's Textbook of Gastroenterology 7e; Tintinalli's Emergency Medicine; Morgan & Mikhail's Clinical Anesthesiology 7e; Lippincott Illustrated Reviews Pharmacology; Park's Textbook of Preventive and Social Medicine.
A quick check of recent literature (last 2 years, systematic reviews/meta-analyses) didn't surface anything that contradicts these standard indications/doses — the ranitidine withdrawal and metoclopramide tardive dyskinesia warning remain the two most clinically important safety updates to keep in mind.
With mechanism
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With Mechanism of Action Added
Here's the same chart with a Mechanism column, plus a simple one-line explanation for each so it's easy to remember.
Simple explanation of mechanism (in plain words)
| Drug | Mechanism in plain words |
|---|---|
| Pantoprazole | Directly blocks the "acid pump" (H+/K+-ATPase) in stomach cells, so acid can't be made at all |
| Ranitidine | Blocks the histamine (H2) signal that tells stomach cells to make acid - weaker than PPI |
| Ondansetron | Blocks serotonin (5-HT3) receptors in the gut and brain's vomiting center, so the "vomit signal" never reaches the brain |
| Buscopan | Blocks acetylcholine (muscarinic) receptors on gut smooth muscle only - muscle relaxes, cramp goes away, doesn't affect the brain |
| Drotaverine | Blocks an enzyme (PDE4) inside smooth muscle cells directly, causing relaxation - not through nerves, so no dry mouth/blurred vision like Buscopan |
| Metoclopramide | Blocks dopamine (D2) receptors - this both stops vomiting (in brain) and makes the stomach squeeze/empty faster (in gut) |
Full chart with mechanism
| Parameter | Pantoprazole | Ranitidine | Ondansetron | Buscopan (Hyoscine butylbromide) | Drotaverine | Metoclopramide |
|---|---|---|---|---|---|---|
| Class | PPI | H2 receptor antagonist | 5-HT3 receptor antagonist | Antimuscarinic antispasmodic | Selective PDE4 inhibitor (musculotropic) | Dopamine D2 antagonist, prokinetic |
| Mechanism of action | Irreversibly binds and inhibits the H+/K+-ATPase ("proton pump") on the luminal surface of gastric parietal cells, blocking the final common step of acid secretion regardless of the stimulus (histamine, gastrin, or acetylcholine) | Competitively blocks histamine H2 receptors on parietal cells, reducing histamine-driven acid secretion (does not block gastrin/ACh-driven acid as completely as PPIs) | Selectively blocks 5-HT3 receptors both centrally (chemoreceptor trigger zone/vomiting center in the brainstem) and peripherally (vagal afferents in the gut wall), interrupting the emetic reflex arc | Blocks muscarinic (M) receptors on GI smooth muscle only - acts topically/peripherally on the gut, does NOT cross into the CNS, so central anticholinergic effects are rare | Selectively inhibits phosphodiesterase-4 (PDE4) inside smooth muscle cells, raising cAMP and causing muscle relaxation - a direct musculotropic effect with no anticholinergic activity | Blocks dopamine D2 receptors both centrally (chemoreceptor trigger zone - antiemetic effect) and peripherally in the gut (removes dopamine's inhibitory brake on cholinergic smooth muscle - prokinetic effect); also has some 5-HT4 agonist and 5-HT3 antagonist action |
| Main indications | Acid reflux/GERD, peptic ulcer, stress ulcer prophylaxis, Zollinger-Ellison syndrome | Peptic ulcer, GERD, dyspepsia (largely replaced by PPIs) | Nausea/vomiting from chemo, radiotherapy, surgery (PONV), gastroenteritis | Abdominal colic, renal/biliary colic, IBS spasm, GI endoscopy prep | Renal colic, biliary colic, dysmenorrhea, GI spasm | Nausea/vomiting, gastroparesis, GERD, aiding gut tube placement, migraine adjunct |
| Contraindications | Hypersensitivity to PPIs; caution with clopidogrel (reduces its activation) | Hypersensitivity; reduce dose in renal impairment; withdrawn/restricted in many countries since 2020 (NDMA contamination concern) | Congenital long QT syndrome; concurrent apomorphine; caution in electrolyte imbalance | Myasthenia gravis, glaucoma, paralytic ileus/mechanical obstruction, urinary retention, tachyarrhythmia | Severe hepatic/renal/cardiac failure, hypersensitivity, AV block, caution in pregnancy/lactation, avoid in young children | Bowel obstruction/perforation, pheochromocytoma, epilepsy, Parkinson disease, children <1 yr |
| Common side effects | Headache, diarrhea, abdominal pain; long-term - low B12/Mg, fracture risk, C. diff risk | Headache, dizziness, constipation; rare confusion in elderly; bradycardia/hypotension/arrhythmia if pushed IV too fast | Headache, constipation, transient flushing, dose-dependent QT prolongation | Dry mouth, blurred vision, tachycardia, urinary retention, constipation | Dizziness, hypotension if given fast IV, headache, nausea | Drowsiness, restlessness, extrapyramidal symptoms/dystonia (especially young women), tardive dyskinesia with prolonged use |
| Adult dose | 40 mg IV/PO OD (up to BD in severe cases) | 50 mg IV q6-8h, or 150 mg PO BD | 4-8 mg IV/IM/PO, may repeat; max single IV dose 16 mg (FDA advisory, QT risk) | 20 mg IV/IM/PO, repeat q6-8h; max 100 mg/day | 40-80 mg IV/IM slow, or PO 40-80 mg 2-3 times/day; max ~240 mg/day | 10 mg IV/IM/PO TID; max 30 mg/day (0.5 mg/kg/day) |
| Safe pediatric dose | ~1 mg/kg/day (specialist guidance advised) | 2-4 mg/kg/day divided (limited current use) | 0.1-0.15 mg/kg/dose (per protocol max) | Not usual <6 months; weight-based under supervision | Generally avoided in young children unless local guideline supports it | AVOID routine use - high dystonia risk; if used, 0.1-0.15 mg/kg, max 3-5 days |
| How to give (IV) | Dilute in NS, slow push over 2 min or infuse over 15 min | Dilute in NS/D5, slow IV over 2 min or infuse over 15-20 min (never rapid push) | Dilute in 20-50 mL NS, infuse over 15 min OR slow push over ≥30 sec-2 min | Slow IV/IM push, undiluted or diluted in small NS volume, over 1-2 min | Slow IV/IM over 2-3 min (rapid push causes hypotension/flushing) | Slow IV push over 1-2 min or short infusion (rapid push causes anxiety/akathisia) |
Why this matters clinically
- Pantoprazole vs Ranitidine: Both lower acid, but pantoprazole shuts off the pump itself (works regardless of what's stimulating acid), while ranitidine only blocks one of three signals (histamine) - that's why PPIs heal ulcers faster and ranitidine has fallen out of favor.
- Buscopan vs Drotaverine: Both relax gut spasm, but through completely different routes. Buscopan works by blocking nerve receptors (muscarinic) - hence the dry mouth/blurred vision. Drotaverine works directly inside the muscle cell via an enzyme (PDE4) - no anticholinergic side effects, which is why it's often preferred when anticholinergic effects need to be avoided (e.g., glaucoma, elderly).
- Ondansetron vs Metoclopramide: Ondansetron only blocks the vomiting signal (serotonin pathway) - it doesn't move the gut. Metoclopramide blocks dopamine, which stops vomiting AND actively speeds up stomach emptying - useful in gastroparesis, but this dopamine blockade is exactly what causes the extrapyramidal/dystonic side effects unique to this drug.
Sources: Harrison's Principles of Internal Medicine 22e; Katzung's Basic and Clinical Pharmacology 16e; Goodman & Gilman's Pharmacological Basis of Therapeutics; Yamada's Textbook of Gastroenterology 7e; Sleisenger and Fordtran's GI and Liver Disease; Lippincott Illustrated Reviews Pharmacology; Maudsley Prescribing Guidelines in Psychiatry 15e; Morgan and Mikhail's Clinical Anesthesiology 7e; Tintinalli's Emergency Medicine.
In detail easy way in chart form
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Detailed Drug Reference Charts (Easy Language)
Each drug now has its own detailed table so nothing gets mixed up. Read top to bottom like a quick-reference card.
1. PANTOPRAZOLE (Pantop)
| Parameter | Details |
|---|---|
| Class | Proton Pump Inhibitor (PPI) |
| Simple mechanism | Shuts off the stomach's "acid pump" completely, no matter what triggers it |
| Technical mechanism | Irreversibly binds the H+/K+-ATPase enzyme on the parietal cell's luminal membrane, blocking the final step of acid secretion (regardless of histamine, gastrin, or acetylcholine stimulation) |
| Onset / Duration | Onset ~1 hr (oral), peak acid suppression in 2-3 days of regular dosing; effect lasts 24+ hrs per dose (irreversible binding) |
| Indications | GERD, peptic ulcer disease, H. pylori regimens (with antibiotics), stress ulcer prophylaxis in ICU, Zollinger-Ellison syndrome, NSAID-induced ulcer prevention |
| Contraindications | Known hypersensitivity to any PPI; caution in severe hepatic impairment |
| Drug interactions | Safest PPI to combine with clopidogrel (doesn't block CYP2C19 like omeprazole does) - preferred PPI in cardiac patients; reduces absorption of drugs needing acid (ketoconazole, iron, some HIV drugs); can raise methotrexate levels |
| Common side effects | Headache, diarrhea, nausea, abdominal pain |
| Serious/long-term effects | Low B12, low magnesium, increased fracture risk, C. difficile infection risk with prolonged use |
| Adult dose | 40 mg IV or PO once daily; up to 40 mg BD in severe reflux/ulcer bleeding |
| Pediatric dose | ~1 mg/kg/day (specialist-guided, not routine in small children) |
| Max safe dose | 80 mg/day (higher doses used short-term in Zollinger-Ellison under specialist care) |
| Pregnancy/lactation | Generally considered low risk; used when clearly needed |
| How to give (IV) | Reconstitute vial, dilute in NS; give slow IV push over 2 minutes OR infuse diluted solution over 15 minutes |
2. RANITIDINE
| Parameter | Details |
|---|---|
| Class | H2-receptor antagonist |
| Simple mechanism | Blocks the "histamine alarm" that tells stomach cells to make acid - weaker than a PPI |
| Technical mechanism | Competitive antagonist at histamine H2 receptors on parietal cells, reducing histamine-driven acid secretion (gastrin/acetylcholine pathways still active) |
| Onset / Duration | Onset 30-60 min (oral), IV faster; duration 6-8 hrs |
| Indications | Peptic ulcer, GERD, dyspepsia, prevention of stress ulcers (now mostly replaced by PPIs) |
| Contraindications | Hypersensitivity; many countries withdrew/restricted ranitidine in 2020 due to NDMA (probable carcinogen) contamination found in various batches - check local availability before prescribing |
| Drug interactions | Reduces absorption of drugs needing acid; can reduce renal excretion of procainamide/quinidine; interacts with phenytoin, warfarin (less than cimetidine) |
| Common side effects | Headache, dizziness, constipation/diarrhea |
| Serious/rare effects | Confusion in elderly, bradycardia/hypotension/arrhythmia if IV given too fast, rare cardiac sympathovagal imbalance |
| Adult dose | 50 mg IV every 6-8 hrs, or 150 mg PO twice daily |
| Pediatric dose | 2-4 mg/kg/day divided (limited current use given safety concerns) |
| Max safe dose | Reduce dose in renal impairment (renally excreted); max 400 mg/day PO |
| Pregnancy/lactation | Crosses placenta; used historically when clinically justified, but PPIs/famotidine now often preferred |
| How to give (IV) | Dilute in NS/D5W; give slow IV over 2 minutes minimum, or better, infuse over 15-20 minutes - never rapid push |
3. ONDANSETRON
| Parameter | Details |
|---|---|
| Class | Serotonin 5-HT3 receptor antagonist (antiemetic) |
| Simple mechanism | Blocks the "vomit signal" from reaching the brain, both from the gut and from the brain itself |
| Technical mechanism | Selectively blocks 5-HT3 receptors centrally (chemoreceptor trigger zone/vomiting center in brainstem) and peripherally (vagal afferent nerve terminals in the gut wall) |
| Onset / Duration | Onset within 30 min (IV faster), duration 4-9 hrs |
| Indications | Chemotherapy/radiotherapy-induced nausea and vomiting, postoperative nausea/vomiting (PONV), vomiting in gastroenteritis |
| Contraindications | Congenital long QT syndrome, concurrent apomorphine use |
| Drug interactions | Additive QT-prolongation with other QT-prolonging drugs (haloperidol, tramadol, some antibiotics); rare serotonin syndrome risk when combined with SSRIs/SNRIs/tramadol |
| Common side effects | Headache, constipation, transient flushing/dizziness |
| Serious/rare effects | Dose-dependent QT prolongation (correct low potassium/magnesium before giving; ECG monitoring advised in at-risk patients), rare serotonin syndrome |
| Adult dose | 4-8 mg IV/IM/PO, may repeat; max single IV dose capped at 16 mg per FDA advisory (higher doses raise QT risk) |
| Pediatric dose | 0.1-0.15 mg/kg/dose |
| Max safe dose | Total daily dose generally kept under 32 mg in divided doses; single IV push capped at 16 mg |
| Pregnancy/lactation | Widely used for hyperemesis gravidarum, though some studies suggest a small increase in fetal anomaly risk - evidence is mixed, discuss risk/benefit |
| How to give (IV) | Dilute in 20-50 mL NS and infuse over 15 minutes, OR give slow IV push over at least 30 seconds to 2 minutes (never rapid bolus) |
4. BUSCOPAN (Hyoscine Butylbromide)
| Parameter | Details |
|---|---|
| Class | Antimuscarinic (anticholinergic) antispasmodic |
| Simple mechanism | Relaxes cramping gut muscle by blocking nerve signals only in the belly, doesn't reach the brain |
| Technical mechanism | Blocks muscarinic acetylcholine receptors on GI (and genitourinary) smooth muscle; poor CNS penetration means classic central anticholinergic effects are rare |
| Onset / Duration | Onset 15-30 min (IV/IM faster, within minutes), duration 4-6 hrs |
| Indications | Abdominal colic, renal/biliary colic, IBS-related spasm, muscle relaxation during GI endoscopy/imaging |
| Contraindications | Myasthenia gravis, angle-closure glaucoma, paralytic ileus/mechanical bowel obstruction, urinary retention (e.g., prostatic enlargement), significant tachyarrhythmia, megacolon |
| Drug interactions | Additive anticholinergic effects with tricyclic antidepressants, antihistamines, other anticholinergics; can antagonize prokinetics like metoclopramide |
| Common side effects | Dry mouth, blurred vision, constipation |
| Serious/rare effects | Tachycardia, urinary retention, rare anaphylaxis |
| Adult dose | 20 mg IV/IM/PO, may repeat every 6-8 hrs |
| Pediatric dose | Not typically used under 6 months; weight-based dosing under supervision for older children |
| Max safe dose | 100 mg/day |
| Pregnancy/lactation | Used when clearly needed; limited systemic absorption when given orally |
| How to give (IV) | Give slow IV or IM push over 1-2 minutes, undiluted or diluted in a small volume of NS |
5. DROTAVERINE
| Parameter | Details |
|---|---|
| Class | Selective phosphodiesterase-4 (PDE4) inhibitor - musculotropic antispasmodic |
| Simple mechanism | Relaxes the spasming muscle directly from inside the cell - no dry mouth or blurry vision like Buscopan |
| Technical mechanism | Selectively inhibits PDE4 within smooth muscle cells, raising intracellular cAMP, which relaxes smooth muscle; has no anticholinergic activity |
| Onset / Duration | Onset 2-4 min (IV), duration 2-3 hrs |
| Indications | Renal colic, biliary colic, dysmenorrhea, GI smooth muscle spasm, sometimes used to aid cervical dilation in labor |
| Contraindications | Severe hepatic/renal/cardiac failure, hypersensitivity, AV block, generally avoided in young children and during breastfeeding |
| Drug interactions | Can potentiate hypotensive effect of levodopa; additive hypotension with antihypertensives |
| Common side effects | Dizziness, headache, nausea |
| Serious/rare effects | Hypotension and flushing if given by rapid IV injection, rare arrhythmia |
| Adult dose | 40-80 mg IV/IM slow injection, or 40-80 mg PO 2-3 times daily |
| Pediatric dose | Generally avoided under 6 years; weight-based dosing only per local pediatric guidelines |
| Max safe dose | ~240 mg/day |
| Pregnancy/lactation | Caution advised; avoid unless clearly indicated |
| How to give (IV) | Give slow IV or IM injection over 2-3 minutes - rapid push risks a drop in blood pressure |
| Note | Not FDA-approved / not marketed in the US; widely used in India, Eastern Europe, and parts of Asia |
6. METOCLOPRAMIDE
| Parameter | Details |
|---|---|
| Class | Dopamine D2-receptor antagonist, prokinetic and antiemetic |
| Simple mechanism | Blocks dopamine, which stops vomiting AND makes the stomach push its contents forward faster |
| Technical mechanism | Blocks D2 receptors centrally (chemoreceptor trigger zone, giving antiemetic effect) and peripherally in the gut (removing dopamine's inhibitory brake on cholinergic smooth muscle, giving prokinetic effect); also has 5-HT4 agonist and weak 5-HT3 antagonist activity |
| Onset / Duration | Onset 1-3 min (IV), 30-60 min (oral); duration 1-2 hrs |
| Indications | Nausea/vomiting, diabetic gastroparesis, GERD, facilitating small bowel feeding tube placement, adjunct in migraine |
| Contraindications | GI obstruction or perforation, pheochromocytoma (can trigger hypertensive crisis), epilepsy, Parkinson's disease, children under 1 year |
| Drug interactions | Increases absorption/effect of some oral drugs by speeding gastric emptying; additive sedation with CNS depressants; additive extrapyramidal risk with antipsychotics |
| Common side effects | Drowsiness, restlessness, diarrhea |
| Serious/rare effects | Extrapyramidal symptoms/acute dystonia (especially young women), tardive dyskinesia with prolonged use - FDA black box warning, rare neuroleptic malignant syndrome, hyperprolactinemia |
| Adult dose | 10 mg IV/IM/PO three times daily |
| Pediatric dose | Avoid routine use; if essential, 0.1-0.15 mg/kg, for a maximum of 3-5 days only |
| Max safe dose | 30 mg/day (0.5 mg/kg/day); FDA advises no more than 12 weeks of continuous treatment, ideally under 5 days for acute use, due to tardive dyskinesia risk |
| Pregnancy/lactation | Commonly used for hyperemesis gravidarum; considered relatively safe in pregnancy |
| How to give (IV) | Slow IV push over 1-2 minutes or short infusion - rapid push increases risk of anxiety/akathisia |
Key Warnings to Highlight
- Ranitidine: Withdrawn or restricted in many countries since 2020 (NDMA contamination) - confirm local availability and consider PPI or famotidine instead.
- Metoclopramide: FDA black box warning for tardive dyskinesia - never use long-term, keep courses short (ideally under 5 days).
- Ondansetron: Check/correct potassium and magnesium before giving; watch for QT prolongation, especially with repeated dosing or in cardiac patients.
- Buscopan: Never give if bowel obstruction, glaucoma, or myasthenia gravis is suspected.
- Pantoprazole: Best PPI choice when a patient is also on clopidogrel, since it doesn't block the enzyme clopidogrel needs to work.
- Drotaverine: Not available/approved in the US - a regional drug used mainly in India, Eastern Europe, and parts of Asia.
Sources: Harrison's Principles of Internal Medicine 22e; Katzung's Basic and Clinical Pharmacology 16e; Goodman & Gilman's Pharmacological Basis of Therapeutics; Yamada's Textbook of Gastroenterology 7e; Sleisenger and Fordtran's GI and Liver Disease; Tintinalli's Emergency Medicine; Rosen's Emergency Medicine; Lippincott Illustrated Reviews Pharmacology; Bailey and Love's Short Practice of Surgery 28e; Maudsley Prescribing Guidelines in Psychiatry 15e.
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