Reflux Medications Compatible with Cephalosporins
H2-receptor antagonists (except cimetidine) and proton pump inhibitors can be safely used with cephalosporins without affecting their absorption, as cephalosporins are not significantly affected by gastric pH changes.
Recommended Reflux Medications
H2-Receptor Antagonists (Preferred Options)
- Famotidine, ranitidine, or nizatidine are safe choices when prescribing cephalosporins, as these agents do not significantly inhibit cytochrome P450 enzymes and do not affect cephalosporin absorption 1
- Avoid cimetidine due to its potent CYP3A inhibition, which can cause drug interactions with other medications the patient may be taking, though it does not directly affect cephalosporin absorption 1
Proton Pump Inhibitors
- Lansoprazole, omeprazole, pantoprazole, and other PPIs are compatible with cephalosporins and do not interfere with their absorption 1
- PPIs are primarily metabolized by CYP2C19 and have minimal interaction potential with cephalosporins 1
Key Pharmacokinetic Considerations
Why These Combinations Are Safe
- Cephalosporins are not dependent on gastric pH for absorption - most oral cephalosporins (cefadroxil, cephalexin, cephradine) have bioavailabilities of 85-90% regardless of gastric acidity 2
- Cephalosporins are eliminated primarily by renal excretion, not hepatic metabolism, making them less susceptible to drug interactions 2
- The active absorption mechanism of cephalosporins in the gastrointestinal tract is not affected by acid suppression 3
Medications to Avoid
Antacids should be avoided or separated by several hours from cephalosporin administration, as they can:
- Prevent absorption of certain antibiotics through chelation or pH effects 1
- While the evidence specifically mentions tetracyclines, azithromycin, and quinolones, the general principle of separating antacids from oral antibiotics applies 1
Clinical Pitfalls to Avoid
- Do not use prokinetic agents like cisapride with cephalosporins if the patient is also taking macrolide antibiotics (erythromycin, clarithromycin), as this creates dangerous cardiac arrhythmia risk through CYP3A inhibition 1
- Metoclopramide is generally safe with cephalosporins but avoid combining with antipsychotic medications due to extrapyramidal effects 1
- Remember that cephalosporins have limited activity against certain organisms and should not be relied upon for MRSA or Pseudomonas coverage 4