Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Capsule, extended release, oral:
Qsymia: 3.75/23: Phentermine 3.75 mg [immediate release] and topiramate 23 mg [extended release] [contains tartrazine]
Qsymia: 7.5/46: Phentermine 7.5 mg [immediate release] and topiramate 46 mg [extended release] [contains tartrazine]
Qsymia: 11.25/69: Phentermine 11.25 mg [immediate release] and topiramate 69 mg [extended release] [contains tartrazine]
Qsymia: 15/92: Phentermine 15 mg [immediate release] and topiramate 92 mg [extended release] [contains tartrazine]
Pharmacology
Mechanism of Action
Phentermine: A sympathomimetic amine with pharmacologic properties similar to amphetamines. The mechanism of action in reducing appetite appears to be secondary to CNS effects, including stimulation of the hypothalamus to release norepinephrine.
Topiramate: Effect on weight management may be due to its effects on appetite suppression and satiety enhancement and based on a combination of potential mechanisms: blocks neuronal voltage-dependent sodium channels, enhances GABA(A) activity, antagonizes AMPA/kainite glutamate receptors, and weakly inhibits carbonic anhydrase.
Use: Labeled Indications
Weight management: Adjunct to a reduced-calorie diet and increased physical activity, in patients with either an initial body mass index (BMI) of ≥30 kg/m2or an initial BMI of ≥27 kg/m2 and at least one weight-related comorbid condition (eg, hypertension, dyslipidemia, type 2 diabetes)
Use: Off Label
Weight management in type 2 diabetes mellitusbyes
In a randomized, double blind, placebo controlled trial, phentermine/topiramate plus lifestyle modifications can effectively promote weight loss and improve glycemic control as a treatment approach in obese/overweight patients with type 2 diabetes Garvey 2014.
According to the American Association of Clinical Endocrinologists and American College of Endocrinology (AACE/ACE) Clinical Practice Guidelines for Medical care of patients with obesity, medication-assisted weight loss phentermine/topiramate should be considered in patients at risk for future type 2 diabetes mellitus and should be used when needed to achieve 10% weight loss in conjunction with lifestyle therapy Garvey 2016.
Contraindications
Hypersensitivity or idiosyncrasy to phentermine or other sympathomimetic amines or any component of the formulation; hyperthyroidism; glaucoma; use during or within 14 days following MAO inhibitor therapy; pregnancy
Dosage and Administration
Dosing: Adult
Weight management: Oral: Initial: Phentermine 3.75 mg/topiramate 23 mg once daily for 14 days. Increase dose to phentermine 7.5 mg/topiramate 46 mg once daily for 12 weeks then evaluate weight loss. If 3% of baseline body weight has not been lost, discontinue use or increase dose to phentermine 11.25 mg/topiramate 69 mg once daily for 14 days, and then to phentermine 15 mg/topiramate 92 mg once daily. Evaluate weight loss after 12 weeks on phentermine 15 mg/topiramate 92 mg; if 5% of baseline body weight has not been lost at dose of phentermine 15 mg/topiramate 92 mg gradually discontinue therapy (eg, 1 dose every other day for at least 1 week).
Weight management in type 2 diabetes mellitus (off-label use): Oral: Phentermine 7.5 mg/topiramate 46 mg or phentermine 15 mg/topiramate 92 mg once daily (Garvey 2014)
Dosing: Geriatric
Refer to adult dosing.
Administration
Administer in the morning without regard to meals; avoid late evening administration (potential for insomnia).
Dietary Considerations
Take in the morning; avoid taking in the late evening. Most effective when combined with a low calorie diet, increased physical activity and behavior modification counseling.
Storage
Store at 15°C to 25°C (59°F to 77°F).
Drug Interactions
Acebrophylline: May enhance the stimulatory effect of CNS Stimulants. Avoid combination
Alcohol (Ethyl): May enhance the CNS depressant effect of Topiramate. Alcohol (Ethyl) may increase the serum concentration of Topiramate. This applies specifically to use with the extended-release topiramate capsules (Trokendi XR). Also, topiramate concentrations may be subtherapeutic in the later portion of the dosage interval. Management: Concurrent use of alcohol within 6 hours of ingestion of extended-release topiramate (Trokendi XR) is contraindicated. Any use of alcohol with topiramate should be avoided when possible and should only be undertaken with extreme caution. Avoid combination
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Alkalinizing Agents: May decrease the excretion of Amphetamines. Management: Consider alternatives to using amphetamines and alkalinizing agents in combination. If these agents must be used together, patients should be monitored closely for excessive amphetamine effects. Consider therapy modification
Alpha-/Beta-Agonists (Indirect-Acting): Carbonic Anhydrase Inhibitors may increase the serum concentration of Alpha-/Beta-Agonists (Indirect-Acting). Monitor therapy
Amantadine: Carbonic Anhydrase Inhibitors may increase the serum concentration of Amantadine. Monitor therapy
Amifampridine: Agents With Seizure Threshold Lowering Potential may enhance the neuroexcitatory and/or seizure-potentiating effect of Amifampridine. Monitor therapy
Amitriptyline: Topiramate may enhance the CNS depressant effect of Amitriptyline. Topiramate may increase serum concentrations of the active metabolite(s) of Amitriptyline. Topiramate may increase the serum concentration of Amitriptyline. Monitor therapy
Ammonium Chloride: May decrease the serum concentration of Amphetamines. This effect is likely due to an enhanced excretion of amphetamines in the urine. Monitor therapy
Amphetamines: Carbonic Anhydrase Inhibitors may decrease the excretion of Amphetamines. Monitor therapy
Antacids: May decrease the excretion of Amphetamines. Monitor therapy
Anticholinergic Agents: May enhance the adverse/toxic effect of Topiramate. Monitor therapy
Antihistamines: Amphetamines may diminish the sedative effect of Antihistamines. Monitor therapy
Antihypertensive Agents: Amphetamines may diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy
Antipsychotic Agents: May diminish the stimulatory effect of Amphetamines. Monitor therapy
Ascorbic Acid: May decrease the serum concentration of Amphetamines. Monitor therapy
AtoMOXetine: May enhance the hypertensive effect of Sympathomimetics. AtoMOXetine may enhance the tachycardic effect of Sympathomimetics. Monitor therapy
Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Consider therapy modification
BuPROPion: May enhance the neuroexcitatory and/or seizure-potentiating effect of Agents With Seizure Threshold Lowering Potential. Monitor therapy
Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
CarBAMazepine: May decrease the serum concentration of Topiramate. Consider therapy modification
Carbonic Anhydrase Inhibitors: May enhance the adverse/toxic effect of other Carbonic Anhydrase Inhibitors. The development of acid-base disorders with concurrent use of ophthalmic and oral carbonic anhydrase inhibitors has been reported. Management: Avoid concurrent use of different carbonic anhydrase inhibitors if possible. Monitor patients closely for the occurrence of kidney stones and with regards to severity of metabolic acidosis. Avoid combination
Carbonic Anhydrase Inhibitors: May decrease the excretion of Amphetamines. Exceptions: Brinzolamide; Dorzolamide. Monitor therapy
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Monitor therapy
Cocaine (Topical): May enhance the hypertensive effect of Sympathomimetics. Management: Consider alternatives to use of this combination when possible. Monitor closely for substantially increased blood pressure or heart rate and for any evidence of myocardial ischemia with concurrent use. Consider therapy modification
CYP2D6 Inhibitors (Moderate): May increase the serum concentration of Amphetamines. Monitor therapy
CYP2D6 Inhibitors (Strong): May increase the serum concentration of Amphetamines. Exceptions: FLUoxetine; PARoxetine. Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Doxofylline: Sympathomimetics may enhance the adverse/toxic effect of Doxofylline. Monitor therapy
Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy
Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Consider therapy modification
Esketamine: May enhance the hypertensive effect of CNS Stimulants. Monitor therapy
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Estrogen Derivatives (Contraceptive): Topiramate may decrease the serum concentration of Estrogen Derivatives (Contraceptive). Contraceptive failure is possible. Management: Risk appears greatest for higher topiramate doses (200 mg/day or greater). Some have recommended using at least 50 mcg/day of ethinyl estradiol, but the effectiveness of this is unclear. Consider a nonhormonal form of contraception. Consider therapy modification
Ethosuximide: Amphetamines may diminish the therapeutic effect of Ethosuximide. Amphetamines may decrease the serum concentration of Ethosuximide. Monitor therapy
Flecainide: Carbonic Anhydrase Inhibitors may increase the serum concentration of Flecainide. Monitor therapy
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification
Fosphenytoin: May decrease the serum concentration of Topiramate. Topiramate may increase the serum concentration of Fosphenytoin. Monitor therapy
Gastrointestinal Acidifying Agents: May decrease the serum concentration of Amphetamines. Monitor therapy
Guanethidine: May enhance the arrhythmogenic effect of Sympathomimetics. Guanethidine may enhance the hypertensive effect of Sympathomimetics. Monitor therapy
HYDROcodone: CNS Depressants may enhance the CNS depressant effect of HYDROcodone. Management: Avoid concomitant use of hydrocodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Iobenguane Radiopharmaceutical Products: Amphetamines may diminish the therapeutic effect of Iobenguane Radiopharmaceutical Products. Management: Discontinue all drugs that may inhibit or interfere with catecholamine transport or uptake for at least 5 biological half-lives before iobenguane administration. Do not administer these drugs until at least 7 days after each iobenguane dose. Avoid combination
Iobenguane Radiopharmaceutical Products: CNS Stimulants may diminish the therapeutic effect of Iobenguane Radiopharmaceutical Products. Management: Discontinue all drugs that may inhibit or interfere with catecholamine transport or uptake for at least 5 biological half-lives before iobenguane administration. Do not administer these drugs until at least 7 days after each iobenguane dose. Avoid combination
Ioflupane I 123: Amphetamines may diminish the diagnostic effect of Ioflupane I 123. Monitor therapy
Iohexol: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Iohexol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iohexol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic anticonvulsants. Consider therapy modification
Iomeprol: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Iomeprol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iomeprol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic anticonvulsants. Consider therapy modification
Iopamidol: Agents With Seizure Threshold Lowering Potential may enhance the adverse/toxic effect of Iopamidol. Specifically, the risk for seizures may be increased. Management: Discontinue agents that may lower the seizure threshold 48 hours prior to intrathecal use of iopamidol. Wait at least 24 hours after the procedure to resume such agents. In nonelective procedures, consider use of prophylactic anticonvulsants. Consider therapy modification
Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
Lacosamide: Antiepileptic Agents (Sodium Channel Blockers) may enhance the adverse/toxic effect of Lacosamide. Specifically the risk for bradycardia, ventricular tachyarrhythmias, or a prolonged PR interval may be increased. Monitor therapy
Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Consider therapy modification
Lithium: Topiramate may increase the serum concentration of Lithium. Monitor therapy
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Monitor therapy
Loop Diuretics: May enhance the hypokalemic effect of Topiramate. Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Mefloquine: May diminish the therapeutic effect of Anticonvulsants. Mefloquine may decrease the serum concentration of Anticonvulsants. Management: Mefloquine is contraindicated for malaria prophylaxis in persons with a history of convulsions. Monitor anticonvulsant concentrations and treatment response closely with concurrent use. Consider therapy modification
Memantine: Carbonic Anhydrase Inhibitors may increase the serum concentration of Memantine. Monitor therapy
MetFORMIN: Topiramate may enhance the adverse/toxic effect of MetFORMIN. Monitor therapy
Methenamine: Carbonic Anhydrase Inhibitors may diminish the therapeutic effect of Methenamine. Management: Consider avoiding this combination. Monitor for decreased therapeutic effects of methenamine if used concomitant with a carbonic anhydrase inhibitor. Consider therapy modification
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy
Mianserin: May diminish the therapeutic effect of Anticonvulsants. Monitor therapy
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Monoamine Oxidase Inhibitors: May enhance the hypertensive effect of Amphetamines. While linezolid and tedizolid may interact via this mechanism, management recommendations differ from other monoamine oxidase inhibitors. Refer to monographs specific to those agents for details. Avoid combination
Multivitamins/Fluoride (with ADE): May decrease the serum concentration of Amphetamines. More specifically, the ascorbic acid (vitamin C) in many multivitamins may decrease amphetamine concentrations. Monitor therapy
Multivitamins/Minerals (with ADEK, Folate, Iron): May decrease the serum concentration of Amphetamines. Monitor therapy
Multivitamins/Minerals (with AE, No Iron): May decrease the serum concentration of Amphetamines. Specifically, vitamin C may impair absorption of amphetamines. Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Orlistat: May decrease the serum concentration of Anticonvulsants. Monitor therapy
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification
PHENobarbital: Amphetamines may decrease the serum concentration of PHENobarbital. Monitor therapy
Phenytoin: Topiramate may increase the serum concentration of Phenytoin. Phenytoin may decrease the serum concentration of Topiramate. Monitor therapy
Pioglitazone: Topiramate may decrease the serum concentration of Pioglitazone. Monitor therapy
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Monitor therapy
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy
Primidone: Carbonic Anhydrase Inhibitors may enhance the adverse/toxic effect of Primidone. Specifically, osteomalacia and rickets. Carbonic Anhydrase Inhibitors may decrease the serum concentration of Primidone. Monitor therapy
Progestins (Contraceptive): Topiramate may decrease the serum concentration of Progestins (Contraceptive). Management: Caution patients that this combination may be associated with reduced contraceptive effectiveness. Consider adding an additional (non-hormonal) contraceptive method. Consider therapy modification
QuiNIDine: Carbonic Anhydrase Inhibitors may decrease the excretion of QuiNIDine. Monitor therapy
Quinolones: Amphetamines may enhance the cardiotoxic effect of Quinolones. Monitor therapy
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy
Salicylates: May enhance the adverse/toxic effect of Carbonic Anhydrase Inhibitors. Salicylate toxicity might be enhanced by this same combination. Management: Avoid these combinations when possible.Dichlorphenamide use with high-dose aspirin as contraindicated. If another combination is used, monitor patients closely for adverse effects. Tachypnea, anorexia, lethargy, and coma have been reported. Consider therapy modification
Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy
Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors): Amphetamines may enhance the serotonergic effect of Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors). This could result in serotonin syndrome. Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors) may increase the serum concentration of Amphetamines. Management: Monitor for increased amphetamine toxicities, including signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability) when these agents are combined. Monitor therapy
Serotonergic Agents (High Risk): Amphetamines may enhance the serotonergic effect of Serotonergic Agents (High Risk). This could result in serotonin syndrome. Management: Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when these agents are combined. Exceptions: Amitriptyline; Amoxapine; ClomiPRAMINE; Desipramine; Dothiepin; Doxepin (Systemic); Doxepin (Topical); FLUoxetine; Imipramine; Isocarboxazid; Linezolid; Lofepramine; Melitracen [INT]; Methylene Blue; Moclobemide; Nortriptyline; PARoxetine; Phenelzine; Protriptyline; Tranylcypromine; Trimipramine. Monitor therapy
Sibutramine: May enhance the adverse/toxic effect of Centrally Acting Weight Loss Agents. Avoid combination
Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification
Solriamfetol: Sympathomimetics may enhance the hypertensive effect of Solriamfetol. Monitor therapy
Solriamfetol: CNS Stimulants may enhance the hypertensive effect of Solriamfetol. Monitor therapy
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification
Sympathomimetics: May enhance the adverse/toxic effect of other Sympathomimetics. Monitor therapy
Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Avoid concomitant use of tapentadol and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Tedizolid: May enhance the hypertensive effect of Sympathomimetics. Tedizolid may enhance the tachycardic effect of Sympathomimetics. Monitor therapy
Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Tetrahydrocannabinol and Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination
Thiazide and Thiazide-Like Diuretics: May enhance the hypokalemic effect of Topiramate. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Topiramate. Management: Monitor for increased topiramate levels/adverse effects (e.g., hypokalemia) with initiation/dose increase of a thiazide diuretic. Closely monitor serum potassium concentrations with concomitant therapy. Topiramate dose reductions may be necessary. Consider therapy modification
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Ulipristal: Topiramate may decrease the serum concentration of Ulipristal. Avoid combination
Urinary Acidifying Agents: May decrease the serum concentration of Amphetamines. Monitor therapy
Valproate Products: Topiramate may enhance the adverse/toxic effect of Valproate Products. Monitor therapy
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification
Adverse Reactions
As reported with combination product (also see individual agents):
>10%:
Cardiovascular: Increased heart rate (>5 bpm: 70% to 78%; >10 bpm: 50% to 56%; >15 bpm: 33% to 37%; >20 bpm: 14% to 20%)
Central nervous system: Paresthesia (4% to 20%), headache (10% to 11%), insomnia (6% to 11%)
Endocrine & metabolic: Decreased serum bicarbonate (6% to 13%; marked reductions [to <17 mEq/L] ≤1%)
Gastrointestinal: Xerostomia (7% to 19%), constipation (8% to 16%)
Respiratory: Upper respiratory tract infection (14% to 16%), nasopharyngitis (9% to 13%)
1% to 10%:
Cardiovascular: Palpitations (≤2%), chest discomfort (≤2%)
Central nervous system: Dizziness (3% to 9%), depression (3% to 8%), anxiety (2% to 8%), cognitive dysfunction (including problems with concentration, memory, and language [word finding]; 2% to 8%), fatigue (4% to 6%), hypoesthesia (4%), disturbance in attention (2% to 4%), irritability (2% to 4%), oral paresthesia (≤2%)
Dermatologic: Alopecia (2% to 4%), skin rash (2% to 3%)
Endocrine & metabolic: Decreased serum potassium (<3.5 mEq/L: 4% to 5%; <3 mEq/L: <1%), hypokalemia (≤3%), increased thirst (2%)
Gastrointestinal: Dysgeusia (metallic taste; 1% to 9%), nausea (4% to 7%), diarrhea (5% to 6%), gastroesophageal reflux disease (3%), dyspepsia (2% to 3%), gastroenteritis (2% to 3%), decreased appetite (2%)
Genitourinary: Urinary tract infection (5%), dysmenorrhea (≤2%)
Infection: Influenza (4% to 8%)
Neuromuscular & skeletal: Back pain (5% to 7%), muscle spasm (3%), musculoskeletal pain (2% to 3%), neck pain (1% to 2%)
Ophthalmic: Blurred vision (4% to 6%), dry eye syndrome (≤3%), eye pain (2%)
Renal: Increased serum creatinine (≥0.3 mg/dL: 2% to 8%; ≥50% over baseline: ≤3%), nephrolithiasis (≤1%)
Respiratory: Sinusitis (7% to 8%), bronchitis (4% to 7%), cough (4% to 5%), pharyngolaryngeal pain (2% to 3%), sinus congestion (2% to 3%), nasal congestion (1% to 2%)
Postmarketing and/or case reports: Acute angle-closure glaucoma, suicidal ideation
Warnings/Precautions
Concerns related to adverse effects:
- Cardiovascular effects: Can increase resting heart rate; monitor closely when starting or increasing dosage, and in patients with cardiac or cerebrovascular disease. Reduce dose or discontinue use with a sustained increase in resting heart rate.
- CNS effects: Cognitive dysfunction and psychiatric disturbances (mood disorders including anxiety, depression or insomnia) may occur with use; incidence of cognitive events (including attention, language, or memory difficulties) may be related to rapid titration and higher doses; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). Risk may be increased in patients with a history of depression; dose reduction or discontinuation may be necessary.
- Glaucoma: Topiramate has been associated with acute myopia and secondary angle-closure glaucoma in adults and children, typically within 1 month of initiation but may occur at any time; discontinue in patients with acute onset of decreased visual acuity or ocular pain.
- Hyperthermia: Topiramate may be associated (rarely) with severe oligohidrosis and hyperthermia; use caution and monitor closely during strenuous exercise, during exposure to high environmental temperature, or in patients receiving other carbonic anhydrase inhibitors and drugs with anticholinergic activity.
- Hypokalemia: Can cause hypokalemia; use caution with concurrent use of hydrochlorothiazide or furosemide as risk of hypokalemia may be increased; monitor potassium closely.
- Hypotension: In hypertensive patients, weight loss in conjunction with antihypertensive therapy may increase the risk of hypotension; monitor blood pressure prior to and during treatment; adjust antihypertensive treatment as necessary.
- Metabolic acidosis (hyperchloremic, nonanion gap): May decrease serum bicarbonate concentrations, due to inhibition of carbonic anhydrase and increased renal bicarbonate loss. Risk may be increased in patients with conditions that predispose to acidosis (eg, diarrhea, ketogenic diet, renal disease, severe respiratory disorders, status epilepticus, surgery) or concurrent treatment with other carbonic anhydrase inhibitors. Monitor serum electrolytes and bicarbonate prior to and during treatment. Reduce dose or discontinue use if persistent metabolic acidosis develops.
- Renal calculus: Use is associated with kidney stone formation. Topiramate exhibits weak carbonic anhydrase inhibitory properties and may increase the risk of kidney stones. The risk of stones may be increased in patients on a ketogenic diet or concurrent treatment with other carbonic anhydrase inhibitors; risk of stones may be reduced by increasing fluid intake.
- Renal effects: May increase serum creatinine; peak increases from baseline were observed after 4 to 8 weeks of treatment. Changes in serum creatinine (and GFR) with short-term use appear reversible with discontinuation; effects of long-term treatment on renal function are not known. Monitor serum creatinine prior to and during treatment. For persistent elevations, dose reduction or discontinuation may be necessary.
- Suicidal ideation: Pooled analysis of trials involving various antiepileptics (regardless of indication) showed an increased risk of suicidal thoughts/behavior (incidence rate: 0.43% treated patients compared to 0.24% of patients receiving placebo); risk observed as early as 1 week after initiation and continued through duration of trials (most trials ≤24 weeks). Avoid use in patients with history of suicide attempts or current suicidal ideation. Monitor all patients for notable changes in depression, suicidal thoughts or behavior; discontinue use in patients who experience suicidal thoughts or behavior.
Disease-related concerns:
- Diabetes: Use with caution in patients with type 2 diabetes mellitus; antidiabetic agent requirements (eg, insulin or oral hypoglycemic agents) may be decreased with weight loss, anorexigens and concomitant dietary restrictions. Monitor blood glucose levels prior to and during treatment.
- Hepatic impairment: Use with caution in patients with hepatic impairment; dosage adjustment may be required. Avoid use in patients with severe hepatic impairment (Child-Pugh class C).
- Renal impairment: Use with caution in patients with renal impairment; dosage adjustment may be required. Avoid use in patients with end-stage renal disease on dialysis.
Concurrent drug therapy issues:
- Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.
Other warnings/precautions:
- Abuse potential: Phentermine is pharmacologically related to the amphetamines, which have a high abuse potential; prolonged use may lead to dependency. Prescriptions should be written for the smallest quantity consistent with good patient care to minimize the possibility of overdose.
- Withdrawal: Anticonvulsants (including topiramate) should not be discontinued abruptly because of the possibility of increasing seizure frequency. Therapy should be withdrawn gradually to minimize the potential of increased seizure frequency, unless safety concerns require a more rapid withdrawal. Tapering doses over at least 1 week (1 dose every other day) is recommended.
Monitoring Parameters
Weight; resting heart rate; serum bicarbonate, potassium, glucose, and serum creatinine (at baseline and periodically during treatment); blood pressure; suicidality or mood disorders; symptoms of secondary angle closure glaucoma; symptoms of acute acidosis and complications of long-term acidosis (eg, nephrolithiasis)
Pregnancy
Pregnancy Risk Factor
X
Pregnancy Considerations
Use of this combination product is contraindicated in pregnant women. An increased risk in oral clefts (cleft lip with or without cleft palate) has been reported with first trimester exposure. Refer to individual monographs for additional information. An increased risk of adverse maternal and fetal outcomes is associated with obesity; however, medications for weight loss therapy are not recommended at conception or during pregnancy (ACOG 156 2015).
Females of reproductive potential should have a negative pregnancy test prior to and monthly during therapy. Effective contraception should be used during treatment.
Health care providers are encouraged to enroll women exposed to Qsymia during pregnancy in the Qsymia Pregnancy Surveillance Program (888-998-4887).
Patient Education
What is this drug used for?
- It is used to help you lose weight.
Frequently reported side effects of this drug
- Headache
- Constipation
- Dry mouth
- Numbness and tingling
- Change in taste
- Nausea
- Diarrhea
- Stuffy nose
- Sore throat
- Back pain
- Loss of strength and energy
Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:
- Low blood sugar like dizziness, headache, fatigue, feeling weak, shaking, fast heartbeat, confusion, increased hunger, or sweating.
- Depression like thoughts of suicide, anxiety, emotional instability, or confusion.
- Acidosis like confusion, fast breathing, fast heartbeat, abnormal heartbeat, severe abdominal pain, nausea, vomiting, fatigue, shortness of breath, or loss of strength and energy.
- Low potassium like muscle pain or weakness, muscle cramps, or an abnormal heartbeat.
- Urinary tract infection like blood in the urine, burning or painful urination, passing a lot of urine, fever, lower abdominal pain, or pelvic pain.
- Kidney stone like back pain, abdominal pain, or blood in the urine.
- Confusion
- Chest pain
- Fast heartbeat
- Severe dizziness
- Passing out
- Trouble focusing
- Trouble with memory
- Trouble speaking
- Trouble sleeping
- Lack of sweat
- Agitation
- Irritability
- Panic attacks
- Mood changes
- Vision changes
- Blurred vision
- Eye redness
- Eye pain
- Eye irritation
- Signs of a significant reaction like wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat.
Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.
Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.
