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Phentermine and Topiramate

Pronunciation

(FEN ter meen & toe PYRE a mate)

Index Terms

  • Phentermine/Topiramate
  • Qnexa
  • Topiramate and Phentermine

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]

Brand Names: U.S.

  • Qsymia

Pharmacologic Category

  • Anorexiant
  • Anticonvulsant, Miscellaneous
  • Sympathomimetic

Pharmacology

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

Chronic weight management, as an adjunct to a reduced-calorie diet and increased physical activity, in patients with either an initial body mass index (BMI) of ≥30 kg/m2 or an initial BMI of ≥27 kg/m2 and at least one weight-related comorbid condition (eg, hypertension, dyslipidemia, type 2 diabetes)

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

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).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

Note: Renal function should be estimated using the Cockcroft-Gault formula with actual body weight.

Mild impairment (CrCl ≥50 mL/minute): No dosage adjustment necessary.

Moderate-to-severe impairment (CrCl <50 mL/minute): Maximum dose: Phentermine 7.5 mg/topiramate 46 mg once daily

Dialysis: Use is not recommended (has not been studied).

Dosing: Hepatic Impairment

Mild impairment (Child-Pugh class A): No dosage adjustment necessary.

Moderate impairment (Child-Pugh class B): Maximum dose: Phentermine 7.5 mg/topiramate 46 mg once daily

Severe impairment (Child-Pugh class C): Use is not recommended (has not been studied).

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

Alkalinizing Agents: May decrease the excretion of Amphetamines. Consider therapy modification

Alpha-/Beta-Agonists (Indirect-Acting): Carbonic Anhydrase Inhibitors may increase the serum concentration of Alpha-/Beta-Agonists (Indirect-Acting). 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

Analgesics (Opioid): CNS Depressants may enhance the CNS depressant effect of Analgesics (Opioid). Management: Avoid concomitant use of opioid analgesics 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

Antacids: May decrease the excretion of Amphetamines. Monitor therapy

Anticholinergic Agents: May enhance the adverse/toxic effect of Topiramate. 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

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

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 patches (Butrans brand) at 5 mcg/hr in adults when used with other CNS depressants. Consider therapy modification

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

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: 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

Contraceptives (Estrogens): Topiramate may decrease the serum concentration of Contraceptives (Estrogens). 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

Contraceptives (Progestins): Topiramate may decrease the serum concentration of Contraceptives (Progestins). Management: Caution patients that this combination may be associated with reduced contraceptive effectiveness. Consider adding an additional (non-hormonal) contraceptive method. Consider therapy modification

Dimethindene (Systemic): 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 (e.g., opioids, barbiturates) with concomitant use. 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

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 I 123: Sympathomimetics may diminish the therapeutic effect of Iobenguane I 123. Avoid combination

Ioflupane I 123: Amphetamines may diminish the diagnostic effect of Ioflupane I 123. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Linezolid: May enhance the hypertensive effect of Sympathomimetics. Management: Reduce initial doses of sympathomimetic agents, and closely monitor for enhanced pressor response, in patients receiving linezolid. Specific dose adjustment recommendations are not presently available. Consider therapy modification

Lithium: Topiramate may increase the serum concentration of Lithium. Monitor therapy

Lofexidine: May enhance the CNS depressant effect of CNS Depressants. 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

MAO 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. Exceptions: Linezolid; Tedizolid. Avoid combination

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: May enhance the CNS depressant effect of CNS Depressants. CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. 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: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirtazapine: CNS Depressants may enhance the CNS depressant effect of Mirtazapine. Monitor therapy

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

Orlistat: May decrease the serum concentration of Anticonvulsants. Monitor therapy

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. 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

Piribedil [INT]: CNS Depressants may enhance the CNS depressant effect of Piribedil [INT]. 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

QuiNIDine: Carbonic Anhydrase Inhibitors may decrease the excretion of QuiNIDine. 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

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

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

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%)

<1% (Limited to important or life-threatening): : Acute angle-closure glaucoma, increased intraocular pressure, suicidal ideation, suicidal tendencies

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 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 and 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 4-8 weeks of treatment. 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 behavior and discontinue use in patients who experience suicidal thoughts or new onset or worsening depression.

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.

Concurrent drug therapy issues:

• Sedatives: Avoid use with other sedative drugs or ethanol; CNS effects may be potentiated

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 Risk Factor

X

Pregnancy Considerations

Use of this combination product is contraindicated in pregnant women. Based on human data, topiramate may cause fetal harm if used during pregnancy. Females of reproductive potential should have a negative pregnancy test prior to and monthly during therapy. Effective contraception should be used during treatment. If irregular bleeding or spotting occurs while using hormonal contraceptives during therapy, patients should be instructed to continue the contraceptive (contraceptive failure is not expected) and notify their health care provider if symptoms become troubling.

The risks of using appetite suppressing drugs in pregnant women are not known. Weight loss therapy is generally not recommended for pregnant women (NHLBI 1998). Obese women should participate in weight reduction programs prior to attempting pregnancy (ACOG 2013). Refer to individual monographs for additional information.

Health care providers are encouraged to enroll women exposed to Qsymia during pregnancy in the Qsymia Pregnancy Surveillance Program (888-998-4887).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience constipation, dry mouth, insomnia, numbness and tingling, change in taste, nausea, diarrhea, or loss of strength and energy. Have patient report immediately to prescriber signs of depression (suicidal ideation, anxiety, emotional instability, or illogical thinking), signs of acidosis (confusion, fast breathing, tachycardia, arrhythmia, severe abdominal pain, nausea, vomiting, fatigue, shortness of breath, or feeling very tired or weak), signs of low potassium (muscle pain or weakness, muscle cramps, or an abnormal heartbeat), signs of a kidney stone (back pain, abdominal pain, or blood in the urine), confusion, angina, tachycardia, severe dizziness, passing out, severe headache, difficulty focusing, memory impairment, difficulty speaking, lack of sweat, agitation, irritability, panic attacks, mood changes, vision changes, eye pain, or eye irritation (HCAHPS).

• Educate patient about signs of a significant reaction (eg, 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. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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