Meta-analyses of the efficacy and tolerability of the tricyclic antidepressant lofepramine

Lessons to be learnt from meta-analyses of newer versus older antidepressants

Meta-analysis is the use of statistical techniques to analyse the findings of many individual analyses (Glass, 1977). It covers all aspects of the review process involving formulating relevant research questions, searching the literature, assessing the quality of studies and choosing relevant ones, extracting and combining the data (for review see Henry & Wilson, 1992; Wilson & Henry, 1992). Meta-analysis as part of a systematic review has advantages over a narrative review but there are problems in applying it in practice (Box 1).

Meta-analytical studies on new antidepressants

A systematic search found 108 meta-analyses of the use of antidepressants in depressive disorders. Defining newer antidepressants as those introduced since the early 1980s, 18 meta-analyses were selected as being informative about their relative efficacy and tolerability in comparative randomised controlled studies (RCTs). Findings with higher confidence include: little difference in efficacy between most new and old antidepressants; superior efficacy of serotonin and noradrenaline re-uptake inhibitors (SNRIs) over selective serotonin re-uptake inhibitors (SSRIs); a slower onset of therapeutic action of fluoxetine over other SSRIs; a different side effect profile of SSRIs to TCAs with superior general tolerability of SSRIs over TCAs; poorer tolerability of fluvoxamine than other SSRIs in a within group comparison; no increased the risk of suicidal acts or ideation in fluoxetine compared with TCAs (or placebo) in low-risk patients. Findings with a lower level of confidence include: greater efficacy of TCAs than SSRIs in in-patients; greater efficacy of amitriptyline than SSRIs; better tolerability of moclobemide than TCAs; no demonstrable difference in tolerability between SSRIs and TCAs in the elderly; no better tolerability of fluvoxamine than TCAs; better tolerability of dothiepin (dosulepin) than SSRIs; better tolerability of sertraline and greater frequency of agitation on fluoxetine than other SSRIs in a within group comparison. In general, the meta-analyses were of uneven quality, as were the studies included, which limits the confidence in many of the results. Generalising from mostly short-term randomised controlled studies to clinical practice requires caution.

The effect of low dose lofepramine in depressed elderly patients in general medical wards

A double-blind randomised controlled trial of the effect of low dose lofepramine (70 mg once daily) against placebo was carried out on depressed elderly inpatients on general medical wards for the elderly, comparing measures of depression and side-effects between the randomised groups. Patients were identified for the study using the Geriatric Depression Scale (GDS) and the Brief Assessment Schedule Depression Cards (BASDEC). Sixty-three subjects were randomised: 46 patients completed the entire trial of 28 days treatment. BASDEC and GDS were administered on day 8 post-admission, and depressed patients were randomised double-blind to either low dose lofepramine (70 mg daily) (n = 23) or placebo (n = 23). Assessment of changes in depressive states were made using the Montgomery Asberg Depression Rating Scale (MADRS) on days 8, 18 and 36 post-admission. Both groups improved by a similar amount during the trial. Lofepramine tended to be more effective than placebo in those patients who were more depressed (GDS > or = 18). On the other hand, subjects who were less depressed (i.e. GDS < 18) improved more on placebo than lofepramine. Low dose lofepramine may prove useful in moderately or severely depressed patients treated for only 4 weeks. However, low dose lofepramine is not indicated for mild (GDS 15-18) depression.

A double-blind controlled comparison of fluoxetine and lofepramine in major depressive illness

One hundred and eighty three patients with DSM-III-R major depressive illness were allocated randomly to treatment with one of two new generation antidepressants, fluoxetine and lofepramine. Both patient groups had significantly lower mean scores on the Hamilton Depression Rating Scale (HDRS) 6 weeks after entry to the trial (p < 0.001), but there were no differences between the groups, either at baseline or after 6 weeks, in total HRDS score or in subscores for anxiety or suicidality. Anticholinergic side effects were commoner with lofepramine; adverse effects were on the whole mild and few patients dropped out because of them. This study does not support previous claims of specific adverse effects of fluoxetine on anxiety and suicidality.

Assessment of epileptogenic potential: experimental, clinical and epidemiological approaches

There are experimental, clinical and epidemiological methods of assessing the epileptogenic potential of psychotropic drugs. In the laboratory it has been shown that there is a range of cellular and synaptic processes in the cerebral cortex and hippocampus that give rise to epileptiform neuronal activity. In addition to the classical suppression of GABA-mediated inhibitory synaptic mechanisms, in vitro studies in animal models of epilepsy and on human tissue suggest a prominent role for the N-methyl D-aspartate (NMDA) subtype of excitatory amino acid receptors. Any mechanism that leads to the depolarization of the neurones is likely to result in a facilitation of the NMDA-receptor involvement in excitatory neurotransmission. This is particularly true in the cortex and hippocampus where the densities of the NMDA-receptor are highest. Data are presented in this paper on how this epileptogenic mechanism can be studied in vitro. In humans, the importance of an accurate diagnosis is stressed and the advantages and disadvantages of routine EEG recordings and ambulatory monitoring discussed. Descriptions of large-scale systems of drug safety monitoring and their application to the assessment of the epileptogenic properties of psychotropic drugs are given.