Orlos (Orlistat)

Orlistat is an anti‑obesity agent that works within the gastrointestinal tract to limit fat absorption.

• Obesity: helps achieve clinically significant weight loss when combined with a reduced‑calorie, low‑fat diet.
• Overweight with co‑morbidities: assists in weight reduction to improve blood pressure, lipid profiles and glycaemic control.
• Weight‑related metabolic syndrome: contributes to modest improvements in waist circumference and insulin sensitivity.

• Orlistat binds covalently to the active site of gastric and pancreatic lipases, irreversibly inhibiting their ability to hydrolyze dietary triglycerides. This blockade prevents the breakdown of triglycerides into absorbable free fatty acids, resulting in the excretion of about 30 % of ingested fat in the feces and a reduction in caloric intake.

Orlistat may cause gastrointestinal and other reactions that vary in frequency and severity.

Common Side Effects

• Oily spotting on under‑clothing.
• Fecal urgency or increased frequency.
• Oily or fatty stools.
• Flatulence with discharge.
• Abdominal discomfort or cramping.
• Reduced absorption of fat‑soluble vitamins (A, D, E, K).

Serious or Rare Side Effects

• Severe hepatic injury.
• Acute pancreatitis.
• Persistent, severe abdominal pain.
• Allergic reactions such as rash, itching or swelling.
• Unexplained fever or chills.
• Persistent watery diarrhea leading to dehydration.

Before initiating therapy, patients should be evaluated for suitability and counseled on dietary fat intake.

• Assess BMI and co‑morbid conditions: confirm indication for weight‑management therapy.
• Review medical history: identify liver disease, malabsorption syndromes or chronic pancreatitis.
• Counsel on low‑fat diet: aim for ≤30 g of fat per meal to minimise gastrointestinal side effects.
• Monitor vitamin levels: supplement fat‑soluble vitamins (A, D, E, K) as recommended.
• Advise on medication timing: separate from other oral drugs by at least 1 hour to avoid absorption interference.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Orlistat can affect the absorption of several concomitant medications and nutrients.

Major Interactions (Avoid)

• Cyclosporine: reduced systemic exposure may compromise immunosuppression.
• Levothyroxine: decreased absorption can lead to sub‑therapeutic thyroid levels.
• Warfarin: altered vitamin K absorption may affect anticoagulation control.

Moderate Interactions (Monitor Closely)

• Orally administered HIV protease inhibitors (e.g., ritonavir): possible reduction in drug exposure.
• Fat‑soluble vitamin supplements: may require dose adjustment or timing separation.
• Lipid‑lowering agents (e.g., fenofibrate): monitor lipid profile for efficacy changes.