Weight-Loss Medications on the Market

According to the US Centers for Disease Control and Prevention, more than one-third of US adults are obese. With obesity on the rise, the FDA recently approved another weight-loss medication.

Contrave was approved in late 2014 as an adjunct to a reduced-calorie diet and increased physical activity for chronic weight management in adults with an initial body mass index (BMI) of:

• 30 kg/m² or greater (obese) or
• 27 kg/m² or greater (overweight) in the presence of at least 1 weight-related comorbidity, such as hypertension, type 2 diabetes mellitus, or dyslipidemia

Contrave is a combination of naltrexone, an opioid antagonist, and bupropion, an antidepressant. The drug does require a 4-week dose titration schedule. Since it consists bupropion, it carries a black-box warning for Suicidality and Antidepressant Drugs, as well as Neuropsychiatric Reactions in Patients taking Bupropion for Smoking Cessation.

Counseling points for Contrave include:

• Swallow tablets whole; do not cut, chew, or crush Contrave tablets. Tell your health care provider if you cannot swallow tablets whole.
• Do not take Contrave with high-fat meals, as it may increase your risk of seizures.
• If you take a urine drug-screening test, Contrave may make the test result positive for amphetamines.

Like Contrave, available weight-loss medications are approved as adjuncts to a reduced-calorie diet and increased physical activity.

Lorcaserin (Belviq) was approved in 2012 and is a serotonin 2C receptor agonist that is taken twice a day. Since Belviq works on serotonin, the risk for serotonin syndrome is present. That being said, pharmacists should be mindful of possible drug interactions with serotonergic medications.

Counseling points for Belviq include:

• Belviq may interact with many medications. Call your doctor immediately if you notice symptoms of serotonin syndrome or neuroleptic malignant syndrome (NMS).
• Belviq can be taken with or without food.

Also approved in 2012 was Qsymia, a combination of phentermine, a sympathomimetic amine anorectic, and topiramate extended-release, an antiepileptic medication. Qsymia is taken once daily in the morning with or without food. Since it contains topiramate, patients may notice concentration, memory, and speech difficulties.

Counseling points for Qsymia include:

• Avoid taking Qsymia in the evening as it may cause insomnia.
• Alcohol in combination with Qsymia can cause dizziness and sleepiness.
• Do not stop taking Qsymia all of a sudden. Discontinuing Qsymia abruptly can increase the risk for seizures.

For all of these weight-loss medications, response should be evaluated after 12 weeks at the maintenance dosage. If a patient has not lost a certain percentage (usually 5%) of baseline body weight, the weight-loss medication should be discontinued, as it is unlikely the patient will achieve and sustain clinically meaningful weight loss if treatment were to be continued.

Orlistat is available as both a prescription (Xenical) and an OTC product (Alli). Xenical and Alli are reversible inhibitors of gastrointestinal lipases.

Xenical is taken 3 times a day with each main meal containing fat (during or up to 1 hour after the meal).

Counseling points for Xenical and Alli include:

• Gastrointestinal events may increase when Xenical and Alli are taken with a diet high in fat (>30% total daily calories from fat).
• Patients may experience oily spotting, flatus with discharge, fecal urgency fatty/oily stool, oily evacuation, increased defecation, and fecal incontinence.
• Patients should take a multivitamin containing fat-soluble vitamins to ensure adequate nutrition.
• Take the vitamin supplement at least 2 hours before or after the administration of Xenical or Alli, such as at bedtime.

Phentermine has been available on the market since the 1950s in a variety of formulations. Phentermine is a sympathomimetic amine anorectic and is usually taken once a day in the morning.

Counseling points for phentermine products include:

• Avoid taking phentermine in the evening as phentermine may cause insomnia.
• Alcohol in combination with phentermine can cause dizziness and sleepiness.
• Tolerance to the anorectic effect usually develops within a few weeks. If this occurs, phentermine should be discontinued.