Managing rapid metabolizers of antidepressants

Depressed patients who rapidly metabolize antidepressants may be common, and may not respond to even high doses of antidepressants if subtherapeutic plasma levels are produced. Rapid metabolizers (RMs) are identifiable if patients are on tricyclic antidepressants (TCAs), and TCA plasma levels (commonly available) are monitored. Strategies to achieve therapeutic levels in RMs include: (1) megaprescribing, or (2) inhibiting the metabolism of the parent drug. Megaprescribing TCAs runs the risk of markedly elevating levels of potentially toxic hydroxy metabolites. In this study twelve depressed, non-responding RMs were identified while taking the TCA, desipramine. Fluoxetine or paroxetine, selective serotonin re-uptake inhibitors (SSRIs) known to potently inhibit cytochrome P450 2D6 (the isoenzyme responsible for desipramine metabolism), was then added to continuing desipramine. Therapeutic range desipramine levels were achieved in ten patients, and seven of the ten achieved excellent or good sustained responses. The combination SSRI and TCA therapy was well tolerated. Whether response primarily reflected the TCA at therapeutic range levels, or a synergistic serotonin-noradrenaline interaction between the respective antidepressants, requires further clarification. The results of this open study suggest the need for controlled trials of antidepressant metabolism inhibition in RMs.

Duration of neuroleptic treatment and prevalence of tardive dyskinesia in late life

BACKGROUND

Although increasing age is the most consistently cited risk factor for the development of tardive dyskinesia for patients in the second to sixth decades of life, this relationship may not hold within geriatric populations.

METHODS

Consecutively admitted geropsychiatric inpatients were examined with the Abnormal Involuntary Movement Scale within 72 hours of admission; comprehensive demographic, diagnostic, and psychometric data were also obtained.

RESULTS

Seventy-four (19.2%) of 386 patients received diagnoses of dyskinesia. Lifetime duration of neuroleptic use was strongly correlated with dyskinesia rates. After accounting for the effect of lifetime duration of neuroleptic use in a stepwise logistic regression, only associations with Global Assessment Scale score and presence of dental problems remained statistically significant. In comparison with the duration of neuroleptic use, however, the contribution of these factors was minor. Sixteen percent of patients with less than 3 months of neuroleptic use, 29% with 3 to 12 months of neuroleptic use, 30% with 1 to 10 years of neuroleptic use, and 41% with more than 10 years of neuroleptic use had dyskinesia. Compared with patients with no history of neuroleptic treatment, the relative risks for these durations of neuroleptic use were 1.62 (95% confidence limits [CL], 0.81, 3.24), 2.89 (95% CL, 1.50, 5.55), 3.08 (95% CL, 1.66, 5.70), and 4.11 (95% CL, 2.12, 7.96), respectively.

CONCLUSIONS

Within elderly populations, duration of exposure to neuroleptics is the strongest predictor of risk for tardive dyskinesia, and this risk increases rapidly within the first year of total lifetime neuroleptic use.

Imipramine and sexual dysfunction during the long-term treatment of recurrent depression

Ninety patients in the maintenance therapy phase of the Pittsburgh Study of Maintenance Therapies in Recurrent Depression (Frank et al., 1990) were studied to determine possible relationships between the type of therapy (imipramine versus no drug) and the level of sexual functioning. The level of sexual functioning was determined by a composite subscale score of the Social Adjustment Scale which assessed (1) current level of enjoyment and interest in sex; (2) change in interest; (3) current frequency of sexual intercourse; (4) change in frequency; and (5) pain and/or difficulty reaching orgasm. Loss of libido was assessed by both the Hamilton Rating Scale for Depression and the SCL-90. Logistic regression analysis revealed no relationship between treatment with active imipramine and sexual functioning for the total group, or for females alone. Analysis of males alone revealed a decreased interest in sex among those treated with imipramine, but no significant differences in frequency or problems. The implications for maintenance pharmacotherapy and the cost/benefit ratio of unacceptable side effects versus drug efficacy are discussed.

Aspects of short REM latency in affective states: a revisit

Electroencephalographic (EEG) sleep changes in affective disorders have been characterized by sleep continuity, slow wave sleep, and rapid eye movement (REM) abnormalities. The most commonly cited feature, however, has been shortened REM latency. Because the diagnostic and prognostic significance of shortened REM latency has been debated, this issue was reexamined in a group of 186 psychotic and nonpsychotic depressed inpatients and outpatients. The analyses suggest an increased frequency of sleep onset REM periods in psychotic depression and in elderly depressed patients (psychotic or nonpsychotic).

Effect of nocturnal intravenous cannulation upon sleep-EEG measures

The effect of an indwelling intravenous cannula on sleep-EEG measures has not been extensively documented despite its relatively frequent use in a variety of clinical studies. When the sleep EEGs from 30 healthy subjects were critically examined, no changes in sleep architecture were found. However, there were significant differences in the distribution of sleep latency, maintenance, and efficiency, with many subjects showing a reduction in the latter two items on the night of cannulation. A decrease in sleep maintenance of greater than 7.5 on the night of cannulation has been used to operationally define an unsatisfactory cannulation study which accounted for 43% of our subjects. It was striking that this group could also be identified by having higher REM densities in each REM period on the previous two nights in the sleep laboratory. This was especially true for the second REM period on the second night when only three of those subjects with subsequent unsatisfactory studies had a REM density less than 0.9. When this criterion was applied to a new group of 19 subjects, 13 were correctly classified with respect to subsequent changes in sleep maintenance before the cannulation study was conducted. It therefore appears possible that REM-sleep measures can be used to predict which subjects will have disrupted sleep on a subsequent cannulation night. Since sleep disruption can significantly mask patterns of hormone secretion, it is essential to monitor the sleep-EEG during such studies.