Generic Name

Pantoprazole

Mechanism

• Selective irreversible inhibitor of the H⁺/K⁺‑ATPase (proton pump) located in the gastric parietal cell secretory canaliculus.
• Binds covalently to cysteine residues on the cytoplasmic domain of the pump, blocking the final step of acid secretion.
• Effects begin within 1–2 h after oral or IV administration and last 24 h, providing sustained acid suppression.
• Absence of significant activity on H₂‑receptors or other ion channels minimizes non‑acid‑related side‑effects.

Pharmacokinetics

• Route: Oral (tablet, delayed‑release), IV (infusion), subcutaneous (pen).
• Absorption: Rapid, peak plasma concentration ~1–2 h post‑dose; bioavailability ≈ 3–5% (oral) due to weak base and first‑pass metabolism.
• Distribution: High plasma protein binding (~95%); penetrates gastric mucus and lesions.
• Metabolism: Hepatic CYP2C19 and CYP3A4 pathways; metabolites largely inactive.
• Elimination: Renal (≈ 24 h half‑life) and biliary; dose adjustment required in renal impairment (CRCl < 30 mL/min).
• Drug interactions:
• CYP2C19 inhibitors (e.g., fluconazole) → ↑ plasma levels.
• CYP2C19 inducers (e.g., rifampin) → ↓ plasma levels.
• Warfarin: modest increase in INR; monitor coagulation.

Indications

• Gastroesophageal reflux disease (GERD) – heartburn symptoms, erosive esophagitis.
• Erosive esophagitis – healing and maintenance.
• Peptic ulcer disease (PUD) – ulcer healing, especially when combined with anti‑infectives for H. pylori.
• Zollinger‑Ellison syndrome – reduction of gastric acid hypersecretion.
• Prevention of NSAID‑induced ulcers – when concomitant therapy with NSAIDs is necessary.
• Maintenance therapy for NSAID‑related or gastric‑ulcers & post‑operative acid suppression.

Contraindications

• Allergy to pantoprazole or any its excipients.
• Severe hepatic impairment (cirrhosis, hepatic failure).
• Co‑administration with medications containing tartrazine or other dyes (rare cross‑reactivity).
• Pregnancy: Category B – use only if clearly needed; avoid during lactation if not essential.

> Warning: Long‑term, high‑dose use (>8 weeks) may increase risk of osteoporotic fractures and Clostridium difficile infection; monitor serum calcium, magnesium.

Dosing

• Self‑chewing tablets: avoid; may lead to unpredictable absorption.
• IV infusion rate: ≤ 2 mg/min; 20 mg diluted in ≥ 50 mL D5W over 15 min.

Adverse Effects

• Common (≥ 1 %):
• Headache, diarrhea, constipation, nausea, abdominal pain, flatulence.
• Hypersensitivity skin rash (rare).
• Serious (≤ 0.1 %):
• Severe cutaneous reactions (e.g., Stevens‑Johnson).
• Hepatotoxicity: ↑ LFTs, fatigue, jaundice.
• Severe hypomagnesemia (manifested as arrhythmias, seizures); monitor Mg²⁺ in long‑term use.
• Occasional paradoxical upper GI bleeding due to bacterial overgrowth.

Monitoring

• Baseline labs: CBC, CMP (hepatic & renal), electrolytes (Mg²⁺, Ca²⁺).
• Follow‑up:
• LFTs and serum Mg²⁺ at 4–6 weeks if therapy >8 weeks.
• INR for patients on warfarin.
• Symptom relief assessment (heartburn score, ulcer healing endoscopy).
• Compliance: Assess bleeding history, acid‑related symptoms, and potential drug‑drug interactions.

Clinical Pearls

1. Delayed‑Release Micro‑capsules: Nil, unlike modified‑release tablets, major strength formulations (20 mg) retain crystal‑coated, sustained release, ensuring consistent plasma levels.
2. Sustained Gastric Acid Suppression: Unlike H₂ antagonists, pantoprazole stays active throughout the night, providing 24‑h coverage ideal for nocturnal GERD.
3. Pharmacogenomics: CYP2C19 poor metabolizers have ~2× higher exposure; consider a lower dose to avoid toxicity.
4. Timing of Admin: Take 30 min before meals for maximum efficacy; IV dose should precede the first meal of the day.
5. Drug‑Drug Interaction Labelling: PPIs displace lisinopril from its renal tubular secretion, possibly elevating serum creatinine for early CYP2C19 genotyping.
6. Ketogenic Diet Impact: In patients on ketogenic diets, pantoprazole’s absorption increases due to altered gastric pH; monitor for hyperchloremic metabolic acidosis signs.

This drug card consolidates all essential pharmacologic facts about pantoprazole for quick reference by medical students and healthcare professionals.