Phentermine / Topiramate Dosage

Medically reviewed by Drugs.com. Last updated on Feb 18, 2019.

• Overview
• Side Effects
• Dosage
• Professional
• Interactions
• Pregnancy
• More

Usual Adult Dose for Weight Loss

All doses expressed as phentermine/topiramate:

Initial dose: 3.75 mg/23 mg orally once a day for 14 days, then 7.5 mg/46 mg orally once a day
-Evaluate weight loss after 12 weeks at 7.5 mg/46 mg; if weight loss is less than 3% of baseline weight, discontinue therapy or escalate dose:

Dose escalation: 11.25 mg/69 mg orally once a day for 14 days, then 15 mg/92 mg orally once a day
-Evaluate weight loss after 12 weeks at 15 mg/92 mg; if weight loss is less than 5% of baseline weight, discontinue therapy.

Maintance dose: 7.5 mg/46 mg OR 15 mg/92 mg orally once a day

Comments:
-Dosing should be in the morning (with or without food) to avoid the possibility of insomnia.
-Doses should be titrated and weight loss evaluated as described above; if percent weight loss is not achieved by stated timeline it is unlikely that patients will achieve and sustain clinically meaningful weight loss and therefore discontinuation is recommended.
-Discontinuation from dose of 15 mg/92 mg once a day should be gradual; decrease to every other day for at least 1 week prior to stopping treatment.

Uses: As an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in patients:
-With an initial body mass index (BMI) of 30 kg/m2 or greater (obese)
-With an initial BMI of 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.

Renal Dose Adjustments

-Mild renal impairment (CrCl 50 mL/min or more): No adjustment recommended
-Moderate to severe renal impairment (CrCl less than 50 mL/min): Maximum dose: phentermine 7.5 mg/topiramate 46 mg orally once a day

Liver Dose Adjustments

-Mild liver impairment (Child-Pugh score 5 to 6): No adjustment recommended
-Moderate liver impairment (Child-Pugh score 7 to 9): Maximum dose: 7.5 mg/topiramate 46 mg orally once a day
-Severe liver impairment (Child-Pugh score 10 to 15): Not recommended

Dose Adjustments

Elderly: Doses selection should be cautious

Drug Discontinuation:
-To prevent a possible seizure, discontinue treatment gradually by taking a dose every other day for at least 1 week prior to stopping treatment altogether.

Precautions

US REMS: The US FDA requires a Risk Evaluation and Mitigation Strategy (REMS) for this drug. It includes a medication guide, elements to assure safe use, and an implementation system. For additional information: www.fda.gov/REMS.

CONTRAINDICATIONS:
-Pregnancy
-Glaucoma
-Hyperthyroidism
-During or within 14 days following the administration of monoamine oxidase inhibitors
-Known hypersensitivity or idiosyncrasy to the sympathomimetic amines

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

US Controlled Substance: Schedule IV

Dialysis

End-stage renal disease on dialysis: Data not available; Avoid use per manufacturer.

Other Comments

Administration advice:
-Take in the morning with or without food

Missed dose: If a dose is missed, wait until the next morning to take usual dose; do not double dose

General:
-The effect of this drug on cardiovascular morbidity and mortality has not been established.
-The safety and effectiveness of this drug in combination with other weight loss products, including prescription and over-the-counter drugs and herbal preparations, have not been established.
-This drug is only available through certified pharmacies enrolled in the Qsymia certified network; additional information may be obtained via the website www.QsymiaREMS.com

Monitoring:
-Obtain a negative pregnancy test before treatment initiation and monthly thereafter in females of reproductive potential.
-Measure blood pressure prior to and during treatment in patients being treated with antihypertensive medications.
-Measure electrolytes including serum bicarbonate prior to and during treatment.
-Monitor patients for the appearance or worsening of metabolic acidosis if they are concomitantly taking a carbonic anhydrase inhibitor and have a predisposing condition for metabolic acidosis.
-Measure blood glucose levels prior to and during treatment in type 2 diabetic patients.
-Monitor for hypokalemia per standard of care.
-Perform appropriate monitoring in situations where immediate termination of this drug is medically required as abrupt withdrawal of topiramate has been associated with seizures in individuals without a history of seizures or epilepsy.
-Monitor for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.
-Measure serum creatinine levels prior to and during treatment.
-Obtain a blood chemistry profile that includes bicarbonate, creatinine, potassium, and glucose at baseline and periodically during treatment.

Patient Advice:
-Patients should be instructed to follow prescribed diet and exercise plan and maintain adequate hydration.
-Patients should be instructed to report persistently elevated pulse or periods of heart pounding or racing at rest; severe side or back pain and/or blood in their urine; changes in attention, concentration, memory, and/or difficulty finding words; changes in mood or depression, or suicidal ideation; and/or symptoms of severe or persistent eye pain or vision changes.
-Patients should avoid driving or operating hazardous machinery until they gauge how this drug affects their performance.
-Patients should avoid alcohol while on therapy.
-Patients should understand this drug may cause fetal harm; a negative pregnancy test is necessary prior to starting therapy and effective contraception are necessary during therapy.
-Patients should be instructed to monitor for decreased sweating and increased body temperature during physical activity, especially in hot weather.
-Patients with diabetes should be instructed to monitor blood sugars carefully and contact their healthcare provider for changes in glycemic control.
-Patients should be instructed not to abruptly discontinue therapy.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer