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Qsymia Dosage

Generic name: phentermine hydrochloride 3.75mg, topiramate 23mg
Dosage form: capsule, extended release

The information at Drugs.com is not a substitute for medical advice. Always consult your doctor or pharmacist.

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)].

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