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Qsymia
phentermine hydrochloride/ topiramate
Adult Dosing .
Dosage forms: CAP: 3.75 mg IR/23 mg ER, 7.5 mg IR/46 mg ER, 11.25 mg IR/69 mg ER, 15 mg IR/92 mg ER
Restricted Distribution in US
- [1-888-998-4887 or www.QsymiaREMS.com for more info]
weight management, chronic
- [7.5 mg/46 mg or 15 mg/92 mg PO qam]
- Start: 3.75 mg/23 mg PO qam x14 days, then incr. to 7.5 mg/46 mg PO qam; Max: 15 mg/92 mg/day; Info: for obese patients or overweight patients with wt-related comorbidity; if wt loss <3% after 12wk on 7.5 mg/46 mg dose, incr. to 11.25 mg/69 mg PO qam x14 days, then 15 mg/92 mg PO qam; D/C if wt loss <5% after 12wk on 15 mg/92 mg dose; taper 15 mg/92 mg dose to 15 mg/92 mg PO qod for at least 1wk to D/C
renal dosing
- [see below]
- CrCl <50: max 7.5 mg/46 mg/day
- HD/PD: avoid use
hepatic dosing
- [see below]
- Child-Pugh Class B: max 7.5 mg/46 mg/day; Child-Pugh Class C: not defined, caution advised
Peds Dosing .
- Dosage forms: CAP: 3.75 mg IR/23 mg ER, 7.5 mg IR/46 mg ER, 11.25 mg IR/69 mg ER, 15 mg IR/92 mg ER
Restricted Distribution in US
- [1-888-998-4887 or www.QsymiaREMS.com for more info]
weight management, chronic
- [12 yo and older]
- Dose: 7.5 mg/46 mg or 15 mg/92 mg PO qam; Start: 3.75 mg/23 mg PO qam x14 days, then incr. to 7.5 mg/46 mg PO qam; Max: 15 mg/92 mg/day; Info: for obese patients; if BMI change <3% after 12wk on 7.5 mg/46 mg dose, incr. to 11.25 mg/69 mg PO qam x14 days, then 15 mg/92 mg PO qam; D/C if BMI change <5% after 12wk on 15 mg/92 mg dose; if wt loss >2 lb/wk, consider dose reduction; taper 15 mg/92 mg dose to 15 mg/92 mg PO qod for at least 1wk to D/C
renal dosing
- [see below]
- CrCl <50: max 7.5 mg/46 mg/day
- HD/PD: avoid use
hepatic dosing
- [see below]
- Child-Pugh Class B: max 7.5 mg/46 mg/day; Child-Pugh Class C: not defined, caution advised
Contraindications / Cautions .
- hypersensitivity to drug or ingredient
- MAO inhibitor use within 14 days
- pregnancy
- breastfeeding
- cardiovascular disease
- cardiovascular disease history
- dialysis
- hyperthyroidism
- glaucoma
- suicidal ideation
- suicidality history
- agitation
- drug abuse history
- abrupt withdrawal
- caution: hypersensitivity to tartrazine
- caution: CNS depressant use, concurrent
- caution: alcohol use, concurrent
- caution: hepatic impairment
- caution: CrCl <50
- caution: hepatic mitochondrial activity, reduced
- caution: metabolic disorder, congenital
- caution: cerebrovascular disease
- caution: depression
- caution: depression history
- caution: diabetes mellitus
- caution: HTN, controlled
- caution: hypokalemia
- caution: nephrolithiasis history
- caution: metabolic acidosis risk
- caution: ketogenic diet
- caution: respiratory disease, severe
- caution: status epilepticus
- caution: surgery
- caution: diarrhea
- caution: dehydration
- caution: environmental temperature, high
- caution: patients of childbearing potential
Drug Interactions .
Overview
phentermine
sympathomimetic amine
- hypertensive effects
- lowers seizure threshold
- tachycardia
- add MAO inhibitor to Interaction Check if recent (14 days) use
topiramate
carbonic anhydrase inhibitor
- CYP3A4 substrate
- CYP2C19 inhibitor, weak
- CYP3A4 inducer, weak
- affected by altered fat absorption
- antiepileptic agent
- CNS depression
- hyperammonemia
- hyperthermia
- hypokalemia
- metabolic acidosis
- potential for modified drug release
- urine alkalinizer
- beverages or products containing ethanol are contraindicated within 6h of topiramate extended-release (ER) capsules administration; combo may incr. topiramate release rate, levels, risk of adverse effects, decr. duration of efficacy
Contraindicated
Avoid/Use Alternative
Monitor/Modify Tx
Caution Advised
Adverse Reactions .
Serious Reactions
- metabolic acidosis, severe
- nephrolithiasis
- osteomalacia
- osteoporosis
- oligohidrosis
- hyperthermia
- hypokalemia
- hyperammonemic encephalopathy
- cardiac ischemia
- tachycardia
- pulmonary HTN
- psychosis
- suicidality
- abuse
- dependency
- glaucoma, secondary angle-closure
- myopia, acute
- maculopathy
- visual field defect
- drug reaction with eosinophilia and systemic symptoms
- Stevens-Johnson syndrome
- toxic epidermal necrolysis
- erythema multiforme
- hypersensitivity reaction
- anaphylaxis
- angioedema
- seizures if abrupt D/C
- growth suppression (peds patients)
Common Reactions
- paresthesia
- xerostomia
- constipation
- dysgeusia
- insomnia
- dizziness
- URI symptoms
- headache
- nausea
- back pain
- fatigue
- diarrhea
- blurred vision
- UTI
- depression
- anxiety
- alopecia
- hypoesthesia
- irritability
- attention disturbance
- fever
- arthralgia
- muscle spasms
- dyspepsia
- GERD
- rash
- dry eyes
- hypokalemia
- eye pain
- thirst
- palpitations
- dysmenorrhea
- tachycardia
- Cr incr.
- cognitive impairment
Safety/Monitoring .
Monitoring Parameters
pregnancy test at baseline, then qmo; BMP, HR at baseline, then periodically; signs/symptoms of depression, behavior changes, suicidality; BP at baseline, then periodically if HTN; height in peds
Pregnancy/Lactation .
Pregnancy
Clinical Summary
phentermine: contraindicated during pregnancy; wt loss during pregnancy offers no benefit and may result in fetal harm; no known risk of teratogenicity when inadvertently used during 1st trimester based on limited human data
topiramate: contraindicated during pregnancy; wt loss during pregnancy offers no benefit and may result in fetal harm; risk of teratogenicity, including oral clefts, and low birth wt based on human data; possible risk of neonatal metabolic acidosis based on drug's mechanism of action and transfer to fetus; risk of neurodevelopmental delay inconclusive
Pregnancy Registry
encourage patients to enroll in Qsymia Pregnancy Surveillance Program at 1-888-998-4887
Individuals of Reproductive Potential
obtain negative pregnancy test before tx start, then qmo during tx; avoid pregnancy by using effective contraception during tx in patients of childbearing potential
Lactation
Clinical Summary
phentermine: avoid use while breastfeeding; no human data available to assess risk of infant harm, though possible drug excretion into milk based on drug properties; may interfere with infant nutrition based on drug's mechanism of action; no human data available to assess effects on milk production
topiramate: weigh risk/benefit while breastfeeding; inadequate human data available to assess risk of infant harm, though drug excreted into milk; no human data available to assess effects on milk production
Pharmacology .
Metabolism: for phentermine: liver minimally; CYP450: 3A4 substrate; for topiramate: liver minimally; CYP450: 3A4 substrate
Excretion: for phentermine: urine (70-80% unchanged); Half-life: 20h; for topiramate: urine 70% (primarily unchanged); Half-life: 65h
Subclass: Obesity/Weight Management: Sympathomimetics
Mechanism of Action
for phentermine: exact mechanism of action unknown; stimulates CNS activity; for topiramate: exact mechanism of action unknown; blocks voltage-dependent sodium channels; augments GABA activity; antagonizes glutamate receptors; inhibits carbonic anhydrase
Formulary .
No Formulary Selected
Manufacturer/Pricing .
Manufacturer: Vivus Inc.
DEA/FDA: Schedule IV
Retail Price
Estimated prices only. For current pricing, visit GoodRx.
oral capsule, extended release:
- 3.75 mg/23 mg (14 ea): $92.00
- 7.5 mg/46 mg (30 ea): $199.00
- 11.25 mg/69 mg (30 ea): $213.00
- 15 mg/92 mg (30 ea): $213.00
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