Phentermine / Topiramate Dosage

Usual Adult Dose for Weight Loss

-Initial dose: Take one capsule of the lowest dose (phentermine 3.75 mg/topiramate 23 mg extended-release) orally once a day in the morning for the first 14 days.

-Maintenance dose: After 14 days, take one capsule of the recommended dose (phentermine 7.5 mg/topiramate 46 mg extended-release) orally once a day in the morning.

Comments:
-Weight loss should be evaluated after 12 weeks with phentermine 7.5 mg/topiramate 46 mg extended-release. If a patient has not lost at least 3% of baseline body weight, treatment discontinuation or dose escalation should be considered as it is unlikely the patient will achieve and sustain clinically meaningful weight loss at this dose.

Use: 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) 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.

Renal Dose Adjustments

-Mild renal impairment (CrCl 50 mL/min or more): No adjustment recommended.
-Moderate renal impairment (CrCl 30 to less than 50 mL/min): Dosing should not exceed phentermine 7.5 mg/topiramate 46 mg extended-release orally once a day in the morning.
-Severe renal impairment (CrCl less than 30 mL/min): Dosing should not exceed phentermine 7.5 mg/topiramate 46 mg extended-release orally once a day in the morning.

Liver Dose Adjustments

-Mild liver impairment (Child-Pugh score 5 to 6): No adjustment recommended.
-Moderate liver impairment (Child-Pugh score 7 to 9): Dosing should not exceed phentermine 7.5 mg/topiramate 46 mg extended-release orally once a day in the morning.
-Severe liver impairment (Child-Pugh score 10 to 15): Data not available; Avoid use per manufacturer.

Dose Adjustments

Evaluate weight loss after 12 weeks of treatment with phentermine 7.5 mg/topiramate 46 mg extended-release:
-If a patient has not lost at least 3% of baseline body weight: Discontinue or escalate the dose to phentermine 11.25 mg/topiramate 69 mg extended-release orally once a day in the morning for 14 days then increase the dose to phentermine 15 mg/topiramate 92 mg extended-release orally once a day in the morning.

Evaluate weight loss after 12 weeks of treatment with phentermine 15 mg/topiramate 92 mg extended-release:
-If a patient has not lost at least 5% of baseline body weight: Discontinue, as it is unlikely the patient will achieve and sustain clinically meaningful weight loss with continued treatment.

How to discontinue treatment:
-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.

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 with or without food.
-Avoid dosing in the evening to prevent possible insomnia.

General:
-The following doses are for titration purposes only: phentermine 3.75 mg/topiramate 23 mg extended-release and phentermine 11.25 mg/topiramate 69 mg extended-release capsules.
-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.

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.