- ACRONYMS AND DEFINITIONS
- ER - Extended-release
- IR - Immediate-release
- ODT - Orally-disintegrating tablet
- Phen - Phentermine
- APPETITE SUPPRESSANTS
Benzphetamine IR (Didrex®)
Dosage forms
Tablet
- 50 mg
Dosing
Weight loss
- Starting: 25 - 50 mg once daily
- Maintenance: 25 - 50 mg one to three times a day
- Max: 150 mg/day
- Take midmorning
Generic / Price
- YES/$Other
- DEA Schedule III
- Tablets are scored so they may be cut in two
Diethylpropion IR (Tenuate®)
Dosage forms
Tablet
- 25 mg
Dosing
Weight loss
- Dosing: 25 mg three times a day
- Max: 100 mg/day
- Take one hour before meals
- A midevening dose may be added to overcome night hunger
Generic / Price
- YES/$Other
- DEA Schedule IV
- Usual starting dose is 25 mg three times a day before meals
- May take a fourth dose midevening to overcome night hunger
Diethylpropion ER (Tenuate Dospan®)
Dosage forms
Tablet, extended-release
- 75 mg
Dosing
Weight loss
- Dosing: 75 mg once daily
- Max: 75 mg once daily
- Take midmorning
Generic / Price
- YES/$Other
- DEA Schedule IV
- Do not cut, chew, or crush tablet
Phendimetrazine IR (Bontril® PDM)
Dosage forms
Tablet
- 35 mg
Dosing
Weight loss
- Dosing: 35 mg two to three times a day
- Max: 210 mg/day (2 tablets 3 times a day)
- Take one hour before meals
Generic / Price
- YES/$Other
- DEA Schedule III
- In some cases, half a tablet (17.5 mg) per dose may be adequate
- Tablets are scored so they may be cut in two
Phendimetrazine ER (Bontril®)
Dosage forms
Capsule, extended-release
- 105 mg
Dosing
Weight loss
- Dosing: 105 mg once daily
- Max: 105 mg once daily
- Take 30 - 60 minutes before morning meal
Generic / Price
- YES/$Other
- DEA Schedule III
Phentermine IR (Adipex-P®)
Dosage forms
Tablet
- 37.5 mg
Capsule
- 15 mg
- 30 mg
- 37.5 mg
Dosing
Weight loss
- Dosing: 37.5 mg once daily
- Max: 37.5 mg once daily
- Tablet can be split and given twice a day
- May take before breakfast or 1-2 hours after breakfast
Generic / Price
- YES/$Other
- DEA Schedule IV
- For some patients, half tablet (18.75 mg) daily may be adequate
- In some cases, it may be desirable to give half tablets (18.75 mg) two times a day
- Tablets are scored so that they may be cut in two
Phentermine IR (Lomaira™)
Dosage forms
Tablet
- 8 mg
Dosing
Weight loss
- Dosing: 1 tablet three times a day 30 minutes before meals
- Max: 8 mg three times a day
- Take 30 minutes before meals
- Tablet may be halved for 4 mg dose
Generic / Price
- NO/$Other
- DEA Schedule IV
- Tablets are scored so that they may be halved
Phentermine (Suprenza™)
Dosage forms
Tablet, orally-disintegrating
- 15 mg
- 30 mg
- 37.5 mg
Dosing
Weight loss
- Dosing: 15 - 37.5 mg once daily
- Max: 37.5 mg once daily
- May be taken without regard to food
Generic / Price
- NO/$$$$Other
- DEA Schedule IV
- Place tablet on tongue where it will dissolve, then swallow with or without water
Qsymia® (phentermine + topiramate)
Dosage forms
Capsule
- Phentermine : Topiramate
- 3.75 : 23 mg
- 7.5 : 46 mg
- 11.25 : 69 mg
- 15 : 92 mg
Dosing
Weight loss (pediatric patients ≥ 12 years and adults)
- Criteria
- Adults: BMI ≥ 30 or ≥ 27 + one weight-related comorbidity
- Children ≥ 12 years: BMI in the ≥ 95th percentile
- Starting: 3.75/23 mg once daily for 14 days then 7.5/46 mg once daily. Take in the morning with or without food.
- Maintenance: 7.5/46 - 15/92 mg once daily
- Max: 15/92 mg once daily
- Evaluate weight loss after 12 weeks on 7.5/46 mg dose. If the patient has not lost ≥ 3% of baseline body weight (or 3% of baseline BMI for children), discontinue or increase to the next highest dose by giving 11.25/69 mg for 14 days, then 15/92 mg once daily.
- After 12 weeks on 15/92 mg, if the patient has not lost ≥ 5% of baseline body weight (or 5% of baseline BMI for children) dose, discontinue Qsymia
- If weight loss exceeds 2 lbs (0.9 kg)/week in children, consider dosage reduction
- When discontinuing the 15/92 mg dose, take every other day for 1 week to avoid precipitating seizures
- The 3.75/23 mg and 11.25/69 mg doses are for titration purposes only
Kidney disease dosing
- CrCl ≥ 50 ml/min: no dose adjustment necessary
- CrCl < 50 ml/min: maximum dose is 7.5/46 mg once daily
- Dialysis: DO NOT USE
Liver disease dosing
- Child-Pugh A: no dose adjustment necessary
- Child-Pugh B: maximum dose is 7.5/46 mg once daily
- Child-Pugh C: DO NOT USE
Lab monitoring
- Pregnancy testing: topiramate has been associated with an increased risk of birth defects, and Qsymia should not be given to pregnant women or women who are trying to become pregnant. Pregnancy testing is recommended before therapy and monthly during treatment, along with effective contraception. Pharmacies must register with the Qsymia REMS program to dispense Qsymia.
- BMP - topiramate inhibits carbonic anhydrase and has been associated with non-anion gap metabolic acidosis in some patients (see topiramate acidosis). Check electrolytes before starting therapy and periodically thereafter. In Qsymia trials, the peak reduction in serum bicarbonate typically occurred within 4 weeks of titration to the assigned dose.
Efficacy
Weight loss in adults
Weight loss in adolescents
Generic / Price
- NO/$$$$Other
- DEA Schedule IV
- Topiramate is a seizure medication. See topiramate for more.
- Kidney disease
- Benzphetamine
- The pharmacokinetics of benzphetamine are not well-defined
- The manufacturer makes no specific recommendations [14]
- Diethylpropion
- Diethylpropion is excreted in the urine, and kidney disease would be expected to reduce its clearance
- The manufacturer recommends caution but makes no specific dosage recommendation [7]
- Phendimetrazine
- Phendimetrazine is primarily excreted by the kidneys, and kidney disease would be expected to reduce its clearance
- The manufacturer makes no specific dosage recommendation [15]
- Phentermine
- Phentermine is excreted in the urine, and kidney disease would be expected to reduce its clearance
- The manufacturer makes no specific dosage recommendation [12]
- Liver disease
- Benzphetamine
- The pharmacokinetics of benzphetamine are not well-defined
- The manufacturer makes no specific recommendations [14]
- Diethylpropion
- Diethylpropion has not been studied in patients with significant liver disease
- The manufacturer makes no specific dosage recommendation [7]
- Phendimetrazine
- Phendimetrazine has not been studied in patients with significant liver disease
- The manufacturer makes no specific dosage recommendation [15]
- Phentermine
- Phentermine has not been studied in patients with significant liver disease
- The manufacturer makes no specific dosage recommendation [12]
- DRUG INTERACTIONS
- NOTE: The drug interactions presented here are NOT all-inclusive. Other interactions may exist. Drug interaction checkers provide the most efficient and practical way to check for interactions among multiple medications. A free interaction checker is available from Drugs.com (see Drugs.com interactions checker).
- All sympathomimetic amines
- MAO inhibitors - MAO inhibitors should not be taken within 14 days of sympathomimetic amines. When taken together, severe hypertension may occur.
- Medications that affect the CNS - any medication that has CNS effects (e.g. antidepressants, antipsychotics, seizure medications, insomnia drugs, bipolar medications) may potentially be affected by the stimulant properties of sympathomimetic amines
- Serotonergic medications - case reports of serotonin syndrome have been reported in patients taking sympathomimetic amines with other serotonergic medications
- Metabolism and clearance
- The metabolism of sympathomimetic amines is not well-defined
- PRICE ($) INFO
Pricing legend
- $ = 0 - $50
- $$ = $51 - $100
- $$$ = $101 - $150
- $$$$ = > $151
- Pricing based on one month of therapy at standard dosing in an adult
- Pricing based on information from GoodRX.com®
- Pricing may vary by region and availability
- BIBLIOGRAPHY
- 1 - PMID 11493122
- 2 - PMID 19564877
- 3 - PMID 15526396
- 4 - PMID 7471128
- 5 - PMID 17066505
- 6 - Phentermine package insert
- 7 - Diethylpropion package insert
- 8 - PMID 11104741
- 9 - PMID 10713017
- 10 - PMID 20920040
- 11 - PMID 9731087
- 12 - Suprenza PI
- 13 - PMID 21481449
- 14 - Didrex PI
- 15 - Bontril PI