Sympathomimetic amine + antiepileptic.
Phentermine HCl/topiramate extended-release; 3.75mg/23mg, 7.5mg/46mg, 11.25mg/69mg, 15mg/92mg; caps.
As an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in adults with an initial BMI of ≥30kg/m2 or ≥27kg/m2 in the presence of at least one weight related co-morbidity (eg, HTN, T2DM or dyslipidemia).
The effect of phentermine on chronic weight management is likely mediated by release of catecholamines in the hypothalamus, resulting in reduced appetite and decreased food consumption, but other metabolic effects may also be involved. The effect of topiramate may be due to its effects on both appetite suppression and satiety enhancement, induced by a combination of pharmacologic effects including augmenting the activity of the neurotransmitter gamma-aminobutyrate, modulation of voltage-gated ion channels, inhibition of AMPA/kainite excitatory glutamate receptors, or inhibition of carbonic anhydrase.
The effect of Qsymia was studied in two trials in obese patients (Study 1) and in obese and overweight patients with two or more significant co-morbidities (Study 2). After 1 year of Qsymia treatment, all dose levels resulted in statistically significant weight loss compared to placebo. A statistically significant greater proportion of the patients randomized to Qsymia than placebo achieved 5% and 10% weight loss.
Take once daily in the AM. Initially 3.75mg/23mg for 14 days; then increase to 7.5mg/46mg and evaluate weight loss after 12 weeks on this dose. If patient has not lost ≥3% baseline body weight, discontinue or escalate dose. To escalate dose: increase to 11.25mg/69mg for 14 days, then increase to 15mg/92mg and evaluate weight loss after additional 12 weeks at this dose. If patient has not lost ≥5% baseline body weight, discontinue by taking a dose every other day for at least 1 week prior to stopping altogether. Qsymia 3.75mg/23mg and 11.25mg/69mg strengths are for titration purposes only. Renal (moderate or severe), hepatic (moderate) impairment: max 7.5mg/46mg once daily.
<18yrs: not established.
Pregnancy (Cat. X). Glaucoma. Hyperthyroidism. Within 14 days of MAOIs.
Can cause fetal harm; obtain negative pregnancy test before starting and monthly thereafter; use effective contraception. ESRD on dialysis, severe hepatic impairment: avoid. Recent or unstable cardiac or cerebrovascular disease: not recommended. Measure resting heart rate regularly. History of suicidal attempts or active suicidal ideation: avoid. Monitor for worsening of depression, suicidal thoughts, unusual behaviors. Depression. Sleep disorders. Measure electrolytes including serum bicarbonate, potassium, creatinine, blood glucose (in diabetics), BP (in patients on antihypertensives) prior to starting and during therapy. Avoid abrupt withdrawal (seizure risk). Monitor for decreased sweating and increased body temperature during physical activity. Nursing mothers: not recommended.
See Contraindications. Avoid alcohol. May potentiate CNS depression with concomitant other CNS depressants (eg, barbiturates, benzodiazepines, hypnotics). Avoid other carbonic anhydrase inhibitors (eg, zonisamide, acetazolamide, methazolamide). Increased risk of hypokalemia with concomitant non-K+-sparing diuretics (eg, furosemide, HCTZ). May be antagonized by phenytoin, carbamazepine. Hyperammonemia w/wo encephalopathy with concomitant valproic acid. May affect oral contraceptives (spotting may occur).
Paraesthesia, dizziness, dysgeusia, insomnia, constipation, dry mouth; acute myopia and secondary angle closure glaucoma (discontinue if occurs), cognitive dysfunction, metabolic acidosis, increased serum creatinine, kidney stones, oligohidrosis, hyperthermia.
Caps 3.75mg/23mg—14, 30; 7.5mg/46mg, 11.25mg/69mg, 15mg/92mg—30