XENICAL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XENICAL (XENICAL).
Reversible inhibitor of gastric and pancreatic lipases, preventing hydrolysis of dietary triglycerides into absorbable free fatty acids and monoglycerides.
| Metabolism | Minimally absorbed; metabolism occurs mainly in the gastrointestinal wall via hydrolysis to inactive metabolites; <1% absorbed drug is metabolized via glucuronidation and oxidation. |
| Excretion | Primarily fecal (approximately 97% of absorbed dose), with less than 2% renal elimination as unchanged drug and metabolites. |
| Half-life | Terminal elimination half-life is approximately 1-2 hours for the parent drug; clinically relevant as rapid clearance limits systemic exposure. |
| Protein binding | Orlistat is highly protein-bound (>99%), primarily to albumin and lipoproteins. |
| Volume of Distribution | Volume of distribution is about 70 L (approx 1 L/kg), indicating extensive distribution into tissues. |
| Bioavailability | Oral bioavailability is extremely low (<1%) due to minimal absorption and extensive first-pass metabolism. |
| Onset of Action | Oral: onset of weight loss effect typically observed within 2 weeks of therapy initiation. |
| Duration of Action | Duration of action is approximately 7 hours after a single oral dose; clinical effect persists with continued dosing. |
| Action Class | Lipase inhibitor |
| Brand Substitutes | Zerofat 120mg Capsule, Reesize 120 Capsule, O-Stat 120 Capsule, Orlifit-N-Slim 120 Capsule, Obeset 120 Capsule |
120 mg orally three times daily with each main meal containing fat (during or up to 1 hour after the meal). Omit dose if meal is skipped or contains no fat.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for renal impairment. Not studied in ESRD. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment. Not studied in severe hepatic impairment (Child-Pugh class C). |
| Pediatric use | Not recommended for use in children <12 years. Adolescents ≥12 years: same adult dose of 120 mg three times daily. |
| Geriatric use | No specific dose adjustment; same as adult dosing. Monitor for potential drug interactions and nutritional deficiencies due to fat malabsorption. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for XENICAL (XENICAL).
| Breastfeeding | No data available on orlistat excretion into human milk. Due to minimal systemic absorption, excretion into breast milk is expected to be insignificant. However, caution is advised. M/P ratio: not determined. |
| Teratogenic Risk | Xenical (orlistat) is minimally absorbed systemically. In animal studies, no evidence of teratogenicity was observed at doses up to 10 times the human dose. There are no adequate and well-controlled studies in pregnant women. Based on negligible systemic absorption, the risk for fetal harm is low. However, due to potential for fat-soluble vitamin deficiency (A, D, E, K) from drug mechanism, maternal supplementation should be considered. No trimester-specific risks identified; avoid use in pregnancy as a precaution. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Chronic malabsorption syndrome","Cholestasis","Hypersensitivity to orlistat or any component","Pregnancy (relative; caution due to weight loss effects)"]
| Precautions | ["Risk of cholelithiasis and cholecystitis due to rapid weight loss","Fat-soluble vitamin deficiencies (A, D, E, K) requiring supplementation","Gastrointestinal adverse effects (steatorrhea, fecal urgency, oily spotting) may worsen with high-fat meals","Interference with thyroid hormone absorption if taken concurrently"] |
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| Fetal Monitoring | Monitor maternal weight and dietary compliance. Assess for fat-soluble vitamin (A, D, E, K) levels especially if prolonged use. Fetal monitoring: routine prenatal care; no specific fetal monitoring required due to low systemic exposure. |
| Fertility Effects | No known adverse effects on fertility. Orlistat does not affect reproductive hormones or fertility parameters in animal studies. Limited human data; no negative impact expected. |