New studies target side effects of psychotropic drugs

June 18, 2001

highlights from the 154th American Psychiatric Association's annual meeting

 

Rx CARE

New studies target side effects of psychotropic drugs

Should anyone be expected to sacrifice sexual satisfaction or experience excessive weight gain in order to obtain psychological well-being? Participants attending the 154th American Psychiatric Association annual meeting, held recently in New Orleans, tackled these issues while exploring what can be done.

Researchers reported the findings from the first study to examine the rates of sexual dysfunction among users of the new-generation antidepressants. In the overall study population of nearly 6,300 patients, bupropion sustained-release tablets (Wellbutrin SR, GlaxoSmithKline) were associated with the lowest rate of sexual dysfunction (25%), followed by bupropion HCl (Wellbutrin) (22%). Those results compared with an average of 40% for all the selective serotonin reuptake inhibitors (SSRIs), venlafaxine (Effexor, Wyeth-Ayerst), and mirtazapine (Remeron, Organon).

Sexual dysfunction can greatly impinge on a patient's quality of life, affect medication compliance, and interfere with recovery from depression, said lead investigator Anita Clayton, M.D., associate professor and vice chair of the Department of Psychiatric Medicine at the University of Virginia.

The tendency for most of the atypical antipsychotics to induce weight gain was also a hot topic at the meeting. One study reported that olanzapine (Zyprexa, Lilly) tended to produce more weight gain as compared with ziprasidone (Geodon, Pfizer). Another study observed that olanzapine-treated patients manifested increased weight gain, fasting insulin levels, total cholesterol levels, and triglyceride levels when compared with patients on ziprasidone. However, emerging data showed that olanzapine-induced weight gain is manageable with clinical and educational intervention.

Kimberly Littrell, M.S., A.P.R.N., president and CEO of the Promedica Research Center in Atlanta, reported the findings for her small pilot study. Schizophrenic patients who participated in a four-month, one-hour-weekly education class on nutrition and exercise gained fewer pounds compared with those receiving no behavioral interventions.

Additional data were also presented on a retrospective study of 145 psychiatric outpatients treated with olanzapine. In this study, only nine patients discontinued olanzapine treatment because of weight gain.

"What we've seen here is that treatment efficacy is a very important factor as it relates to medical adherence and, ultimately, to a favorable treatment outcome," said L. Jan Findlay, R.N., C.N.S., the University of Alabama at Birmingham.

Pharmacological interventions may also prove helpful in controlling weight gain. New data demonstrated that the use of 300-mg, twice-daily nizatidine (Axid, Lilly) reduced treatment-emergent weight gain by approximately 50% among patients taking olanzapine. Bruce Kinon, M.D., senior clinical researcher at Lilly, noted that nizatidine was chosen after feedback from clinicians indicated that patients on nizatidine reported decreased appetite and weight loss, though the mechanism for this action is unknown.

In addition, in another study, topiramate (Topamax, Ortho-McNeil), an anticonvulsant medication, was shown to produce weight loss among schizophrenic patients taking an array of neuroleptic agents.

The focus of the meeting was not only to address the side effect issues but also to highlight new drug developments.

An investigational drug shows promise as a nonstimulant alternative for treating attention deficit hyperactivity disorder (ADHD), according to David Michelson, M.D., medical director at Eli Lilly. "Atomoxetine seems to work by blocking the norepinephrine transporter and doesn't involve the dopamine receptors directly. Therefore, it has a different mechanism of action from that of the stimulants commonly used to treat ADHD," he commented.

So far, in several randomized studies, atomoxetine has been found to be superior to placebo in controlling ADHD symptoms. Lilly intends to submit an application to the Food & Drug Administration for approval of atomoxetine later this year.

Another agent expected to be submitted for FDA approval later this year is Forest Laboratories' memantine, an investigational agent for Alzheimer's disease. Results presented from a phase III study demonstrated a potential benefit for patients with moderately severe to severe Alzheimer's disease treated with memantine, as compared with those treated with placebo. This benefit was shown by positive outcomes in measures of cognition, day-to-day function, and overall performance.

Memantine is able to protect neurons from excessive stimulation by the excitatory neurotransmitter glutamate by blocking the N-methyl-D-aspartate receptor. It is believed that this unique mechanism of action produces clinical effects differently from the agents currently available to treat Alzheimer's, while also targeting a patient population that has progressed beyond the mild to moderate stages of the disease.

Tammy Chernin, R.Ph.

 



Tammy Chernin. New studies target side effects of psychotropic drugs.

Drug Topics

2001;11:20.