Orlistat interacts with a defined set of drug classes, and is contraindicated in chronic malabsorption syndrome and cholestasis. Screening for these before the first dose prevents almost all serious events.
Interaction classes to screen
| Class | Concern | Action |
|---|---|---|
| Metabolic inhibitors | Raised plasma levels and exaggerated effect | Reduce dose or space administration |
| Metabolic inducers | Reduced exposure and treatment failure | Review response and adjust |
| Same-target agents | Additive pharmacology | Avoid duplicate therapy |
| Agents affecting the same organ system | oily stool, flatulence, faecal urgency, fat-soluble vitamin loss | Monitor and document |
Key takeaways
- Screen every new prescription against the patient's full medicine list.
- Common reactions, oily stool, flatulence, faecal urgency, fat-soluble vitamin loss, are amplified by interacting drugs.
- Document the interaction check in the dispensing record.
- Re-screen whenever another long-term medicine is added.
Monitoring in practice
Most interaction risk is manageable with a scheduled review after the onset window of effects on fat absorption from the first dose and one further check at steady state. Patients on multiple chronic medicines benefit from an annual structured medication review.
Orlistat at a glance
| Attribute | Detail |
|---|---|
| Drug class | gastric and pancreatic lipase inhibitor |
| Common brand | Xenical / Alli |
| Licensed use | weight management alongside a reduced-fat diet |
| Available strengths | 60 mg, 120 mg |
| Dosage form | capsule |
| Typical onset | effects on fat absorption from the first dose |
| Duration / dosing interval | acts locally in the gut per dose |
| Storage | below 25 °C |
