Qsymia (Page 5 of 11)

6.2 Postmarketing Experience

The following adverse reactions have been reported during post approval use of QSYMIA, phentermine, and topiramate. Because these reactions are reported voluntarily from a population of uncertain size it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

QSYMIA

Psychiatric: suicidal ideation, suicidal behavior

Ophthalmic: acute angle closure glaucoma, increased intraocular pressure

Phentermine

Allergic Reactions: urticaria

Cardiovascular: elevation of blood pressure, ischemic events

Central Nervous System: euphoria, psychosis, tremor

Reproductive: changes in libido, impotence

Topiramate

Dermatologic: bullous skin reactions (including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), pemphigus

Gastrointestinal: pancreatitis

Hepatic: hepatic failure (including fatalities), hepatitis

Metabolic: hyperammonemia with or without encephalopathy has been reported with concomitant valproic acid [see Drug Interactions (7)], hypothermia

Ophthalmic: maculopathy

7 DRUG INTERACTIONS

Table 7 displays clinically significant drug interactions with QSYMIA.

Table 7. Clinically Significant Drug Interactions with QSYMIA
Monamine Oxidase Inhibitors
Clinical Impact Concomitant use of phentermine with monoamine oxidase inhibitors (MAOIs) increases the risk of hypertensive crisis.
Intervention Concomitant use of QSYMIA is contraindicated during MAOI treatment and within 14 days of stopping an MAOI.
Oral Contraceptives
Clinical Impact Co-administration of multiple-dose QSYMIA 15 mg/92 mg once daily with a single dose of oral contraceptive containing 35 µg ethinyl estradiol (estrogen component) and 1 mg norethindrone (progestin component), in obese otherwise healthy volunteers, decreased the exposure of ethinyl estradiol by 16% and increased the exposure of norethindrone by 22% [see Clinical Pharmacology (12.3)] . Although this interaction is not anticipated to increase the risk of pregnancy, irregular bleeding (spotting) may occur more frequently due to both the increased exposure to the progestin and lower exposure to the estrogen, which tends to stabilize the endometrium.
Intervention Inform patients not to discontinue their combination oral contraceptive if spotting occurs, but to notify their healthcare provider if the spotting is troubling to them.
CNS Depressants Including Alcohol
Clinical Impact The concomitant use of alcohol or CNS depressant drugs (e.g., barbiturates, benzodiazepines, and sleep medications) with phentermine or topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.
Intervention Advise patients not to drive or operate machinery until they have gained sufficient experience on QSYMIA to gauge whether it adversely affects their mental performance, motor performance, and/or vision. Caution patients against excessive alcohol intake when taking QSYMIA. Consider QSYMIA dosage reduction or discontinuation if cognitive dysfunction persists. [see Warnings and Precautions (5.6)] .
Non-Potassium Sparing Diuretics
Clinical Impact Concurrent use of QSYMIA with non-potassium sparing diuretics may potentiate the potassium-wasting action of these diuretics. Concomitant administration of hydrochlorothiazide alone with topiramate alone has been shown to increase the C max and AUC of topiramate by 27% and 29%, respectively.
Intervention When QSYMIA is used concomitantly with non-potassium-sparing diuretics, measure potassium before and during QSYMIA treatment [see Warnings and Precautions (5.15)and Clinical Pharmacology (12.3)] .
Antiepileptic Drugs
Clinical Impact Concomitant administration of phenytoin or carbamazepine with topiramate in patients with epilepsy, decreased plasma concentrations of topiramate by 48% and 40%, respectively, when compared to topiramate given alone [see Clinical Pharmacology (12.3)] . Concomitant administration of valproic acid and topiramate has been associated with hyperammonemia with and without encephalopathy. Concomitant administration of topiramate with valproic acid in patients has also been associated with hypothermia (with and without hyperammonemia).
Intervention Consider measuring blood ammonia in patients in whom the onset of hypothermia or encephalopathy has been reported [see Clinical Pharmacology (12.3)] .
Carbonic Anhydrase Inhibitors
Clinical Impact Concomitant use of topiramate with any other carbonic anhydrase inhibitor may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation.
Intervention Avoid the use of QSYMIA with other drugs that inhibit carbonic anhydrase. If concomitant use of QSYMIA with another carbonic anhydrase inhibitor is unavoidable, monitor patient for the appearance or worsening of metabolic acidosis [see Warnings and Precautions (5.8, 5.13)] .
Pioglitazone
Clinical Impact A decrease in the exposure of pioglitazone and its active metabolites were noted with the concurrent use of pioglitazone and topiramate in a clinical trial. The clinical relevance of these observations is unknown.
Intervention Consider increased glycemic monitoring when using pioglitazone and QSYMIA concomitantly [see Clinical Pharmacology (12.3)].
Amitriptyline
Clinical Impact Some patients may experience a large increase in amitriptyline concentration in the presence of topiramate.
Intervention Any adjustments in amitriptyline dose when used with QSYMIA should be made according to the patient’s clinical response and not on the basis of amitriptyline levels [see Clinical Pharmacology (12.3)] .

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