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Qsymia Dosage

Generic name: PHENTERMINE HYDROCHLORIDE 3.75mg, TOPIRAMATE 23mg
Dosage form: capsule, extended release

Medically reviewed on March 28, 2018.

General Dosing and Administration

Determine the patient's BMI. BMI is calculated by dividing weight (in kilograms) by height (in meters) squared. A BMI conversion chart (Table 1) based on height [inches (in) or centimeters (cm)] and weight [pounds (lb) or kilograms (kg)] is provided below.

Table 1. BMI Conversion Chart
Table 1

In adults with an initial BMI of 30 kg/m2 or greater or 27 kg/m2 or greater when accompanied by weight-related co-morbidities such as hypertension, type 2 diabetes mellitus, or dyslipidemia prescribe Qsymia as follows:

  • Take Qsymia once daily in the morning with or without food. Avoid dosing with Qsymia in the evening due to the possibility of insomnia.
  • Start treatment with Qsymia 3.75 mg/23 mg (phentermine 3.75 mg/topiramate 23 mg extended-release) daily for 14 days; after 14 days increase to the recommended dose of Qsymia 7.5 mg/46 mg (phentermine 7.5 mg/topiramate 46 mg extended-release) once daily.
  • Evaluate weight loss after 12 weeks of treatment with Qsymia 7.5 mg/46 mg.
    If a patient has not lost at least 3% of baseline body weight on Qsymia 7.5 mg/46 mg, discontinue Qsymia or escalate the dose, as it is unlikely that the patient will achieve and sustain clinically meaningful weight loss at the Qsymia 7.5 mg/46 mg dose.
    To escalate the dose: Increase to Qsymia 11.25 mg/69 mg (phentermine 11.25 mg/topiramate 69 mg extended-release) daily for 14 days; followed by dosing Qsymia 15 mg/92 mg (phentermine 15 mg/topiramate 92 mg extended-release) once daily.
  • Evaluate weight loss following dose escalation to Qsymia 15 mg/92 mg after an additional 12 weeks of treatment.
    If a patient has not lost at least 5% of baseline body weight on Qsymia 15 mg/92 mg, discontinue Qsymia as directed, as it is unlikely that the patient will achieve and sustain clinically meaningful weight loss with continued treatment.
  • Qsymia 3.75 mg/23 mg and Qsymia 11.25 mg/69 mg are for titration purposes only.

Discontinuing Qsymia

  • Discontinue Qsymia 15 mg/92 mg gradually by taking a dose every other day for at least 1 week prior to stopping treatment altogether, due to the possibility of precipitating a seizure [see Warnings and Precautions (5.12)].

Dosing in Patients with Renal Impairment

In patients with moderate (creatinine clearance [CrCl] greater than or equal to 30 and less than 50 mL/min) or severe (CrCl less than 30 mL/min) renal impairment dosing should not exceed Qsymia 7.5 mg/46 mg once daily. Renal impairment is determined by calculating CrCl using the Cockcroft-Gault equation with actual body weight [see Warnings and Precautions (5.13) and Clinical Pharmacology (12.3)].

Dosing in Patients with Hepatic Impairment

In patients with moderate hepatic impairment (Child-Pugh score 7 - 9), dosing should not exceed Qsymia 7.5 mg/46 mg once daily [see Warnings and Precautions (5.14) and Clinical Pharmacology (12.3)].

Further information

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

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