Orlistat Vs. Qsymia: Drug Comparison

Orlistat is the active ingredient in the brand-name medication Xenical^®. The information below is about brand name Xenical. According to the FDA, “Generic medicines use the same active ingredients as brand-name medicines and work the same way, so they have the same risks and benefits as the brand-name medicines.”

Xenical (orlistat) is a prescription medication used for weight management by inhibiting the enzyme lipase, which reduces the absorption of dietary fats in the intestines, thereby helping with weight loss. Its FDA-approved indication is for obesity management, including weight loss and weight maintenance, in conjunction with a reduced-calorie diet. Xenical is available in capsule form and is typically taken three times daily with meals containing fat. Common side effects include gastrointestinal issues such as oily stools, flatulence, and frequent bowel movements, especially after consuming high-fat meals. Xenical can affect the absorption of fat-soluble vitamins, and patients are advised to take a multivitamin supplement to avoid deficiencies.

Qsymia^® (phentermine and topiramate) is a prescription medication used for chronic weight management in adults with obesity or overweight with at least one weight-related condition, such as hypertension, type 2 diabetes, or high cholesterol. It combines two active ingredients: phentermine, an appetite suppressant, and topiramate, which induces a feeling of fullness and reduces appetite. Qsymia is intended to be used alongside a reduced-calorie diet and increased physical activity. Common side effects include dry mouth, constipation, and tingling sensations in the hands and feet. It should be used with caution due to potential risks such as mood changes, increased heart rate, and birth defects if taken during pregnancy.

Reversible inhibitor of gastrointestinal lipases

Phentermine: sympathomimetic amine anorectic

Topiramate: anticonvulsant

Xenical (orlistat) is indicated:

• For obesity management including weight loss and weight maintenance when used in conjunction with a reduced-calorie diet

• To reduce the risk for weight regain after prior weight loss

Qsymia (phentermine and topiramate) is indicated:

• As an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in:

  • Adults with an initial body mass index (BMI) of:

    • 30 kg/m² or greater (obese) or

    • 27 kg/m² or greater (overweight) in the presence of at least one weight-related comorbidity such as hypertension, type 2 diabetes mellitus, or dyslipidemia

  • Pediatric patients aged 12 years and older with BMI in the 95th percentile or greater standardized for age and sex

• Typically taken three times daily

• Comes in 120 mg capsules

• Typically taken orally once daily

• Comes in 3.75 mg/23 mg, 7.5 mg/46 mg, 11.25 mg/69 mg, and 15 mg/92 mg extended-release capsules

Most common treatment emergent adverse reactions (≥5% and at least twice that of placebo) include:

• Oily spotting

• Flatus with discharge

• Fecal urgency

• Fatty/Oily stool

• Oily evacuation

• Increased defecation

• Fecal incontinence

Most common adverse reactions in adults (incidence ≥5% and at least 1.5 times placebo) are:

• Tingling sensation

• Dizziness

• Altered taste

• Insomnia

• Constipation

• Dry mouth

Most common adverse reactions in pediatric patients aged 12 years and older (incidence ≥4% and greater than placebo) are:

• Depression

• Dizziness

• Joint pain

• Fever

• Influenza

• Ligament sprain

• Pregnancy

• Chronic malabsorption syndrome

• Cholestasis

• Known hypersensitivity to Xenical or to any component of this product

• Drug interactions: cyclosporine, fat-soluble vitamin supplements and analogues, levothyroxine, warfarin, amiodarone, antiepileptic drugs, antiretroviral drugs

• Pregnancy

• Glaucoma

• Hyperthyroidism

• Taking or within 14 days of stopping monoamine oxidase inhibitors

• Known hypersensitivity to any component of Qsymia or idiosyncrasy to sympathomimetic amines

• Drug interactions: Oral contraceptives, central nervous system (CNS) depressants including alcohol, non-potassium sparing diuretics

• Xenical has drug interactions and can decrease vitamin absorption

• Take a multivitamin supplement that contains fat-soluble vitamins to ensure adequate nutrition

• Rare cases of severe liver injury with hepatocellular necrosis or acute hepatic failure have been reported

• Patients may develop oxalate nephrolithiasis and oxalate nephropathy following treatment with Xenical

• Substantial weight loss can increase the risk of cholelithiasis

• Exclude organic causes of obesity (e.g., hypothyroidism) before prescribing Xenical

• Gastrointestinal events may increase when Xenical is taken with a diet high in fat (>30% total daily calories from fat)

• Breastfeeding: Caution should be exercised when administered to a nursing woman

• Embryo-fetal toxicity: Can cause fetal harm

• Increase in heart rate

• Suicidal behavior and ideation

• Risk of ophthalmologic adverse reactions

• Mood and sleep disorders

• Cognitive impairment: May cause disturbances in attention or memory, or speech/language problems

• Slowing of linear growth

• Metabolic acidosis

• Decrease in renal function

• Serious skin reactions

• Breastfeeding: Breastfeeding not recommended

*This information is from the label for brand name Xenical^®. See the Full Prescribing Information for more complete information. Orlistat, the active ingredient in Xenical, may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient orlistat.

*This information is from the label for brand name Qsymia^®. See the Full Prescribing Information for more complete information.