Fenfluramine and phentermine

Nursing, Feb 1997 by Shuster, Joel

A 37-YEAR-OLD WOMAN WAS ADMITTED to the hospital for treatment of osteomyelitis that developed after her left tibia was crushed in an automobile accident. For the previous 9 months, she'd taken 20 mg of fenfluramine q.i.d. and 15 mg of phentermine resin daily to treat obesity. However, she was in the hospital for 5 days before her fenfluramine and phentermine (fenphen) treatment could be restarted.

After 2 days back on the fen-phen combination, she had severe gastrointestinal (GI) discomfort and awoke during the night. These symptoms continued on and off for 2 to 3 more days. The patient hadn't had these problems 9 months earlier when she'd started fen-phen therapy.

To help her sleep, she received 30 mg of the benzodiazepine temazepam for 3 nights. Afterward, her sleeping problems and GI symptoms resolved. What went wrong? This patient suffered an adverse reaction to the fen-phen combination.

Even though a patient may not have suffered adverse reactions initially, a medication may affect her differently when she restarts it.

What precautions can you take? Be prepared for the possibility that your patient may experience adverse reactions when restarting a drug that she'd taken previously. If she's beginning or restarting fen-phen therapy, keep these points in mind:

Monitor her blood pressure and ask her to report feelings of excessive fatigue or stimulation.

Give this therapy in the morning so it won't interfere with her sleep. Limit the number of beverages containing caffeine you give her. Watch her for symptoms of depression if fen-phen is discontinued abruptly. U

This column discusses adverse drug reactions and methods of prevention. Dr. Shuster is a clinical professor at Temple University and a clinical pharmacist at Allegheny University Hospital, East Falls, both in Philadelphia. Send examples of adverse drug reactions to: Joel Shuster PharmD, The Institute for Safe Medication Practices, 300 W. Street Rd., Warminster, PA 1897M3231, or fax the information to (215) 956-9266. E-mail: shuster@alleghe ny.edu. If we use your item, we'll publish it anonymously and send you an honorarium of $25.