Obesity medications, side effects

The newest appetite suppressant, sibutramine (Meridia), works by blocking the reuptake of both serotonin and norepinephrine. It does not stimulate nerve cells to release serotonin, as do fenfluramine and dexfenfluramine. Administered at 20 mg/ day, sibutramine effectively reduces weight in obese patients, but its use has not been assessed in eating disorder patients. The most common side effects of this medication are insomnia, dry mouth, and constipation. It has not been associated with the more serious heart and lung complications observed with fenfluramine and dexfenfluramine. Because sibutramine acts in part through modulation of norepinephrine, there is no rational basis for coadministering phentermine, which acts via this same mechanism. 

Helen P. is an obese 27-year-old woman who has been taking the antidepressant desipramine. She was started on a low dose and gradually increased to a dose of 300 mg daily, which she has been taking for the past three months. Even though Helen has only in the last two months been able to notice an effect, she now reports a significant improvement in her depression and no side effects. Her physician has forwarded results of periodic desipramine blood levels to you, and all are within therapeutic range. However, Helen recently discovered that a coworker also takes this medication, in a dose of 150 mg daily, and is doing well. 

New pharmacological treatments have been developed for the treatment of obesity. These include the combination of phentermine and fenfluramine (phen-fen) and, alternatively, dexfenfluramine (Redux). Phentermine (Fastin, lonamin) is a stimulant and fenfluramine (Pondimin) is a serotonin agonist. In combination they have persistent appetite suppression and weight loss effects. These medications can cause anxiety and insomnia and must be used with extreme caution if taken with antidepressants, especially SSRIs. Dexfenfluramine works similarly, but avoids the side effect of increased anxiety, and instead tends to cause diarrhea, dry mouth, and somnolence. There have also been reports of pulmonary hypertension, a potentially fatal condition, especially when taken for longer than three months. Some researchers (Ricuarte et al. 1991 McCann et al. 1994) have expressed concern because rats given these medications showed evidence of neuronal toxicity. Thus, they are effective medications, but must be used with caution. 

S)-(+) Dexfenfluramine (Redux ) 21, a serotonin reuptake inhibitor, has been marketed in Europe and the United States as a very effective anti-obesity drug. This isomer, obtained by resolution of racemic fenfluramine using d-camphoric acid, exhibits a greater anorectic effect than die (R)-(-) and racemic forms, since it is more selective on serotonin as a 5-HT agonist (22). As a result of reports of imdesirable side effects, e.g., valvular heart disease, Redux has been wididrawn from the market, while further studies continue. Racemic fluoxetine (Prozac ) (22) is widely used for treatment of major depression and is one of the most commonly prescribed medications. It is also approved for treatment of obsessive compulsive disorder and bulimia. Non-racemic fluoxetine and its intermediates have been prepared by chemical, enzymatic. 

A 16-week, double-blind, placebo-con-trolled study of the effectiveness of an anorectic drug as an adjunct in the management of obese patients in private practice compared Tenuate (diethylpropion) 25 mg ti.d., Tenuate placebo, and Tenuate alternating for 4 weeks with placebo (12 ). Every two weeks patients were examined (blood pressure, pulse rate), weighed and questioned regarding the effectiveness of the medication, adherence to diet and exercise programme and occurrence of side effects. At the final visit, the physical examination, ECG and chest X-ray were repeated. Systolic blood pressure increased 3.1 mm Hg for the intermittent group and decreased 7.8 mm Hg... 

---