OMECLAMOX-PAK
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OMECLAMOX-PAK (OMECLAMOX-PAK).
Omeprazole is a proton pump inhibitor that irreversibly inhibits the H+/K+ ATPase enzyme system (proton pump) at the secretory surface of gastric parietal cells, suppressing basal and stimulated gastric acid secretion. Clarithromycin is a macrolide antibiotic that binds to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis. Amoxicillin is a semisynthetic penicillin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs).
| Metabolism | Omeprazole: extensively metabolized in the liver primarily by CYP2C19 and CYP3A4. Clarithromycin: metabolized in the liver primarily by CYP3A4. Amoxicillin: partially metabolized by hydrolysis to penicilloic acid. |
| Excretion | Amoxicillin: 60-70% renal (glomerular filtration and tubular secretion), remainder fecal via bile; Omeprazole: ~80% renal (metabolites), ~20% fecal; Clarithromycin: 20-30% renal (unchanged), ~40% fecal (metabolites). |
| Half-life | Amoxicillin: 1-1.5 h (prolonged in renal impairment); Omeprazole: 0.5-1 h (single dose), 1-1.5 h (repeated dosing); Clarithromycin: 3-4 h (single dose), 5-7 h (steady-state). |
| Protein binding | Amoxicillin: 17-20% (albumin); Omeprazole: 95-97% (albumin and alpha1-acid glycoprotein); Clarithromycin: 70-75% (albumin). |
| Volume of Distribution | Amoxicillin: 0.3-0.5 L/kg; Omeprazole: 0.3-0.4 L/kg; Clarithromycin: 200-300 L (not L/kg, approx 3-4 L/kg in 70 kg adult; actual Vd ~3-4 L/kg). |
| Bioavailability | Amoxicillin: 74-92% oral (fasting); Omeprazole: 30-40% oral (first-pass metabolism); Clarithromycin: 50-55% oral (food delays absorption, no significant effect on extent). |
| Onset of Action | Oral: Amoxicillin 1-2 h; Omeprazole 1-3 h (max effect at 2-6 h); Clarithromycin 1-2 h. |
| Duration of Action | Amoxicillin: 6-8 h (in utero); Omeprazole: 24 h (acid suppression); Clarithromycin: 8-12 h. |
| Molecular Weight | Three active components: Omeprazole 345.42 Da, Amoxicillin 365.4 Da, Clarithromycin 747.96 Da |
OMECLAMOX-PAK (omeprazole 20 mg + clarithromycin 500 mg + amoxicillin 500 mg) combination pack: one tablet of omeprazole 20 mg and one tablet of clarithromycin 500 mg and one capsule of amoxicillin 500 mg orally twice daily for 10 days.
| Dosage form | CAPSULE, TABLET, CAPSULE, DELAYED RELEASE |
| Renal impairment | For CrCl 30-89 mL/min: no dose adjustment. For CrCl <30 mL/min: use with caution; not recommended. For hemodialysis: not recommended. |
| Liver impairment | Child-Pugh Class A and B: no adjustment. Child-Pugh Class C: avoid use (clarithromycin contraindicated in severe hepatic failure). |
| Pediatric use | Not approved for use in pediatric patients (safety and efficacy not established). |
| Geriatric use | No specific dose adjustment; use with monitoring for renal function and potential increased risk of adverse effects (e.g., QT prolongation, Clostridium difficile infection). |
| 1st trimester | Avoid due to risk of teratogenicity; amoxicillin is generally safe but omeprazole may cause fetal malformations; clarithromycin is associated with increased risk of miscarriage and cardiovascular defects. |
| 2nd trimester | Use only if clearly needed; weigh risks vs benefits. Clarithromycin has been linked to increased risk of miscarriage. |
| 3rd trimester | Use only if clearly needed; clarithromycin may increase risk of infantile hypertrophic pyloric stenosis in neonates. |
Clinical note
Comprehensive clinical and safety monograph for OMECLAMOX-PAK (OMECLAMOX-PAK).
| Placental transfer | Amoxicillin crosses placenta readily; omeprazole likely crosses; clarithromycin crosses placenta with fetal concentrations ~20% of maternal. |
| Breastfeeding | Omeprazole and amoxicillin are excreted in breast milk in small amounts; clarithromycin is excreted in higher amounts. Potential for GI disturbance and alteration of infant gut flora. Use with caution, especially in neonates. |
■ FDA Black Box Warning
None
| Serious Effects |
Known hypersensitivity to any component (omeprazole, amoxicillin, clarithromycin)Concurrent use with cisapride, pimozide, ergot alkaloids, or HMG-CoA reductase inhibitors metabolized by CYP3A4 (e.g., simvastatin, lovastatin)History of cholestatic jaundice or hepatic dysfunction with clarithromycinHistory of severe immediate-type hypersensitivity to beta-lactam antibiotics (e.g., anaphylaxis)QT prolongation or concurrent use of drugs that prolong QT interval
| Precautions | Clarithromycin: increased risk of cardiac arrhythmias (QT prolongation, ventricular tachycardia, torsades de pointes) in patients with existing QT prolongation, electrolyte disturbances, or concurrent use with other QT-prolonging drugs., Clarithromycin: hepatotoxicity, including hepatic failure and jaundice., Clarithromycin: exacerbation of myasthenia gravis., Omeprazole: long-term use associated with increased risk of Clostridium difficile-associated diarrhea, osteoporosis-related fractures, vitamin B12 deficiency, and hypomagnesemia., Amoxicillin: serious hypersensitivity reactions (anaphylaxis, serum sickness) and severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis)., Amoxicillin: development of drug-resistant bacteria., Antibiotic-associated pseudomembranous colitis due to Clostridium difficile. |
Loading safety data…
| Lactation Rating | L3 - Moderately Safe |
| Teratogenic Risk | OMECLAMOX-PAK (amoxicillin, clarithromycin, omeprazole) assigns amoxicillin to FDA pregnancy category B and clarithromycin to category C, with omeprazole having conflicting data. First trimester: Clarithromycin is associated with a small increased risk of spontaneous abortion and cardiovascular malformations; omeprazole has mixed evidence for a possible increase in major malformations, though recent studies suggest no major teratogenic risk. Second and third trimester: Amoxicillin is considered safe; clarithromycin and omeprazole should be avoided unless essential, as data on fetal effects are limited. Overall, the combination is contraindicated in pregnancy unless no safer alternative exists. |
| Fetal Monitoring | Monitor maternal liver function tests (LFTs) and renal function periodically due to omeprazole and clarithromycin metabolism. Assess for Clostridioides difficile infection if diarrhea develops. For fetus: Ultrasound to assess for cardiovascular malformations if clarithromycin exposure in first trimester. No specific fetal monitoring required for amoxicillin or omeprazole, but growth and development should be followed clinically. |
| Fertility Effects | No specific effects on fertility reported for this combination. Clarithromycin and amoxicillin may transiently alter vaginal flora, but no evidence of impaired fertility. Omeprazole has no known effects on fertility. |
| Food/Dietary | Take with food to reduce gastrointestinal discomfort. Avoid alcohol during treatment and for 48 hours after completion. No specific food restrictions otherwise, but omeprazole's absorption may be slightly reduced if taken with food; however, the combination with antibiotics necessitates administration with meals. Clarithromycin absorption is unaffected by food. |
| Clinical Pearls | OMECLAMOX-PAK is a fixed-dose combination of omeprazole, clarithromycin, and amoxicillin used for Helicobacter pylori eradication. Key points: (1) Take twice daily with food to enhance compliance and reduce GI side effects. (2) Complete the full 10-14 day course even if symptoms resolve to prevent resistance. (3) Contraindicated in patients with known hypersensitivity to any component, especially penicillins or macrolides. (4) May cause metallic taste (clarithromycin) and diarrhea (amoxicillin); warn patients. (5) Check for drug interactions: clarithromycin is a strong CYP3A4 inhibitor; avoid with colchicine, statins, and certain anticoagulants. |
| Patient Advice | Take both morning and evening doses with food at the same times each day. · Complete the entire course of therapy even if you feel better. · Common side effects include metallic taste, diarrhea, nausea, and headache. · Avoid alcohol during treatment and for 48 hours after finishing. · Report severe or persistent diarrhea, skin rash, or difficulty breathing. · This medication may interact with other drugs; inform your doctor of all medications. · Store at room temperature away from moisture and heat. |