Health benefits of weight-management medications

The health benefits of weight-management medications are mainly attributed to reductions in body fat1as well as reductions in dietary fat absorption (orlistat) and improvements in glucoregulation (liraglutide). Generally, improvements in cardiovascular risk following treatment with weight- management medications are correlated with the amount of weight loss and the number of risk factors at baseline.

That is, patients with a greater number or severity of cardiovascular risk factors tend to have greater improvements in those risk factors. Some weight-management medications may reduce the number of other drugs needed to treat weight-related comorbidities and slow the development or progression of type 2 diabetes.

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Table 2. Overview of weight-management pharmacotherapies (approved agents as of September 2014)

Drug Indications and use Drug interactions Adverse experiences and precautions Contraindications, use in specific populations
Phentermine HCl or resin*46,47 Sympathomimetic amine anorectic
Dose: available in a range of doses up to 37.5 mg

Dose should be individualized to obtain an adequate response.

Should be taken in the morning to prevent insomnia.

MAOIs potentiate effect of phentermine and may cause hypertensive crisis.

Phentermine may decrease hypotensive effect of guanethidine.

SSRIs: Sympathomimetic effects of phentermine and risk of serotonin syndrome may be increased.

Common adverse reactions: Paresthesia

Rare cases of primary pulmonary hypertension have been reported.

Discontinue if the following symptoms emerge: dyspnea, angina pectoris, syncope, or lower-extremity edema.

Hypothyroidism, glaucoma, pregnancy, sensitivity to sympathomimetic amines, moderate to severe hypertension, history of CVD, drug abuse, agitated states, or psychiatric illness, including anorexia and depression

During or within 14 days of taking MAOIs

Nursing mothers: Discontinue drug or nursing. Not recommended for use in children under age 12 years Use with caution in geriatric patients and in patients with renal impairment.

Orlistat48 Intestinal lipase inhibitor; impairs absorption of dietary fat. Dose: 120 mg TID with each meal Advise reduced-calorie diet with 30% of calories from fat.

Advise a multivitamin that contains fat-soluble vitamins (2 h before or after taking orlistat) to ensure adequate nutrition.

Can decrease cyclosporine exposure.

Administer 2 h after orlistat

Can reduce absorption of fat-soluble vitamins

Administer levothyroxine 4 h apart from orlistat. Monitor for changes in thyroid function.

Warfarin: Monitor for changes in coagulation parameters.

Antiepileptic drugs: Monitor for changes in severity or frequency of convulsions.

Common adverse reactions: oily spotting, flatus with discharge, fecal urgency, fatty/oily stool, oily evacuation, increased defecation, and fecal incontinence

Rare cases of severe liver injury have been reported.

Pregnancy, chronic malabsorption syndrome, cholestasis, known hypersensitivity to orlistat

Nursing mothers: Use with caution.

Lorcaserin HCl Serotonin (5-HT2C) receptor agonist

Dose: 10 mg bid

Due to risk of serotonin syndrome, use with caution in combination with the following drugs: serotonergic drugs (SSRIs, SNRIs), MAOIs, triptans, bupropion, dextromethorphan, St. John’s Wort. Common adverse reactions:

Patients without T2DM: headache, dizziness, fatigue, nausea, dry mouth, constipation

Patients with T2DM: hypoglycemia, headache, back pain, cough, fatigue


Nursing mothers: discontinue drug or nursing.

Not recommended for pediatric use

Phentermine HCl/topiramate extended-release Combination of phentermine (sympathomimetic amine anorectic) and topiramate extended-release (antiepileptic drug)

Dose: Should be taken in the am to prevent insomnia. Available in 4 doses that can be titrated if necessary.

MAOIs: risk of hypertension

Oral contraceptives: altered exposure may cause irregular bleeding but not increased risk of pregnancy.

CNS depressants and alcohol: Potentiates CNS depressant effects. Avoid concomitant alcohol use.

Non-potassium sparing diuretics: may potentiate hypokalemia

Common adverse reactions: paresthesia, dizziness, dysgeusia, insomnia, constipation, and dry mouth

Fetal toxicity: Women of reproductive potential should obtain monthly pregnancy tests.

Increase in heart rate: Monitor heart rate in all patients.

Pregnancy, glaucoma, hyperthyroidism.

Monthly pregnancy test required

Nursing mothers: Discontinue drug or nursing.

Not recommended for pediatric use

During or within 14 days of taking MAOIs

Known hypersensitivity or idiosyncrasy to sympathomimetic amines

Do not exceed 7.5/46 mg in patients with moderate or severe renal impairment, or patients with moderate hepatic impairment.

Naltrexone/ bupropion Combination of the antidepressant bupropion and the drug/alcohol addiction treatment naltrexone

Dose escalation schedule: Week 1: 1 tablet in the morning, none in the evening;

Week 2: 1 tablet in the morning, 1 tablet in the evening;

Week 3: 2 tablets in the morning, 1 tablet in the evening;

Week 4, 2 tablets in the morning, 2 tablets in the evening

MAOIs: Increased risk of hypertensive reactions can occur when used concomitantly.

Consider dose reduction with any of the following drugs: antidepressants (e.g., SSRIs and many tricyclics), antipsychotics (e.g., haloperidol, risperidone, and thioridazine), beta-blockers (e.g., metoprolol) and Type 1C antiarrhythmics (e.g., propafenone and flecainide).

Do not exceed 1 tablet

BID when taken with CYP2B6 inhibitors (e.g., ticlopidine, clopidogrel).

Can increase bupropion exposure. Avoid concomitant use with CYP2B6 inducers (e.g., ritonavir, lopinavir, efavirenz, carbamazepine, phenobarbital, and phenytoin).

Dose with caution in drugs that lower seizure threshold.

CNS toxicity can occur during concomitant use with dopaminergic drugs (levodopa and amantadine).

Common adverse reactions: nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea Seizure disorders, anorexia or bulimia nervosa, or undergoing abrupt discontinuation of alcohol, benzodiazepines, barbiturates, and antiepileptic drugs

Use of other bupropion-containing products

Chronic opioid use

During or within 14 days of taking a MAOI

Known allergy to any of the active ingredients Pregnancy