Sedative properties of doxepin in comparison with diazepam

Effects of 10 mg and 15 mg oral procyclidine on critical flicker fusion threshold and cardiac functioning in healthy human subjects

The critical flicker fusion threshold (CFFT) is thought to index alertness and cortical arousal. Sedative drugs reduce CFFT while psychostimulants increase it. Procyclidine is an anticholinergic that is used to control the extrapyramidal side-effects of antipsychotics in schizophrenia. This study examined the effects of clinically relevant doses of oral procyclidine administration on CFFT and heart rate in two separate experiments (Experiment 1, drug dose: 10 mg, n = 16; Experiment 2, drug dose: 15 mg, n = 12) involving healthy subjects using a double-blind, placebo-controlled, cross-over design. 10 mg procyclidine had no significant effect on CFFT, heart rate or self-ratings of mood, but the 15 mg dose significantly lowered CFFT at 1 h and 2 h after procyclidine administration, increased drowsiness ratings and produced a drop in heart rate. The effects observed in this study may have implications for treatment compliance of schizophrenic patients, choice of antipsychotics, prescribing to patients with heart disease and monitoring of cardiac function under treatment. Further investigations are required to quantify the effects of procyclidine on CFFT and cardiac function in patients with schizophrenia.

Critical flicker fusion threshold and anticholinergic effects of chronic antidepressant treatment in remitted depressives

The persistence of deficits in cognitive performance in major depressive patients taking maintenance antidepressant medication was assessed by examining groups of patients in clinical remission, stable on one of a range of tricyclics or selective serotonin re-uptake inhibitors (SSRIs) for at least 3 months, compared with controls. Measures of critical flicker fusion (CFF), choice reaction time (CRT), subjective sedation, and anticholinergic side-effect score were made. Tricyclic antidepressants (TCAs) produce a significant deficit in critical flicker fusion threshold compared both to controls and SSRIs. Similar effects were seen with choice reaction times which were significantly affected by age. Sedation scores were significantly higher with TCAs than SSRIs. Anticholinergic side effects were strongly related to CFF, less so to visual analogue sedating scales and not significantly to CRT. The effect measured by CFF is different from sedation, and may be related to the anticholinergic potency of the drug; it may be considered a drug-induced pseudodementia. This effect represents a risk factor for accidents during maintenance therapy and may impair work and leisure performance. The relative risk of weight gain with TCAs compared to SSRIs in women was 5.92 (95% CI 1.79-19.50).

Facilitation of adaptation and acute tolerance to stressful sensory input by doxepin and scopolamine plus amphetamine

This work characterizes a new methodologic and pharmacologic approach to control terrestrial and space motion sickness (SMS). The experimental design allowed separate evaluation of drug action on susceptibility and adaptability, and used repeated measures to approximate the chronic stressful motion of microgravity. Daily exposure to cross-coupled angular acceleration for 5 consecutive days demonstrated that the efficacy of doxepin and scopolamine plus amphetamine in the prevention of autonomic system dysfunction was not only apparent on the first test day (P < .01), but was also evident in the substantially enhanced resistance developed over the 5-day test period (P < .01) as compared with placebo. This indicates that daily use of these medications does not diminish therapeutic efficacy (tolerance). The efficacy of doxepin was anticipated because it possesses pharmacologic properties similar to those of established anti-motion sickness drugs. Comparable efficacy after doxepin loading for 4 hours, 3 days, or 21 days suggests a mechanism distinct from its antidepressant effects, possibly related to its potent antihistaminergic actions. Use of doxepin has operational significance to the National Aeronautics and Space Administration, in comparison with current preparations of scopolamine plus amphetamine, because of doxepin's minimal impact on cognitive performance, and most importantly, its favorable pharmacokinetic profile, particularly its long half-life.

Second generation antidepressants: a comparative review

The authors review four "second generation" antidepressants (maprotiline, amoxapine, trazodone, and nomifensine) in terms of action on biogenic amines and receptors, antidepressive efficacy, and adverse effects. Doxepin is used as a comparative agent and is similar to the prototypical tricyclic agents in all the above categories. Maprotiline is a selective noradrenergic agent, but shares a similar adverse effect profile with doxepin and may be associated with a high frequency of seizures in overdose. Amoxapine is a mixed action antidepressant with significant neuroleptic activity in vivo. Its adverse effect profile is highlighted by symptoms related to its neuroleptic activity, and seizures and acute renal failure in overdose. Trazodone is a selective serotonergic agent with low anticholinergic activity, and minimal morbidity/mortality in overdose. Reports of priapism, leading to impotence in some men, however, is of concern. Nomifensine is a potent noradrenergic and dopaminergic agent with low anticholinergic activity, and minimum cardiotoxicity and low morbidity/mortality in overdose. Its most important adverse effects include overstimulation and infrequent, usually reversible, immunologic hypersensitivity reactions. Trazodone and nomifensine have favorable profiles for use in the elderly. Trazodone may be more favorable in the anxious/agitated patient due to its sedative effects, whereas nomifensine may be more beneficial in the retarded, apathetic patient.

Effects of zimeldine and other antidepressants on skilled performance: a comprehensive review

Existing data suggest that amitriptyline, doxepin, mianserin, viloxazine and imipramine impair the performance of skilled psychomotor tasks. The degree of impairment, as well as the degree of interaction with alcohol, is closely related to the sedative potency of the drug. the adverse effects on psychomotor skills are, however, mainly limited to the first 10 days of treatment. In contrast, nortriptyline, clomipramine, desipramine, protriptyline, nomifensine and zimeldine have much less marked effects on skilled performance. Despite its being a relatively new antidepressant, the effects of zimeldine on psychomotor skills have already been extensively investigated. It has been shown to be without stimulant or sedative effects, and there does not appear to be any additive effect between zimeldine and ethanol. The lack of detrimental effects on skills related to such tasks as driving, makes zimeldine suitable for use in out-patient populations.

Sedative effects and prolactin response to single oral doses of melperone

The pharmacokinetics of melperone and the relationship between plasma concentration and the effect on arousal and prolactin secretion after single oral doses (10, 25, 50 and 100 mg) was studied in normal subjects. Dose-dependent kinetics were indicated by the fact that higher plasma concentrations than expected were demonstrated after the 100-mg dose. Melperone decreased arousal and increased prolactin secretion in a dose-dependent manner. The level of arousal was correlated to melperone plasma concentration over the entire dose range. Prolactin secretion was also correlated to melperone plasma concentration, provided the relationship was studied separately for the individual melperone doses. Thus at higher doses, higher plasma concentrations are needed to elicit the same prolactin outflow. The possibility that reduced arousal reactions might contribute in the antipsychotic action of neuroleptic drugs was discussed.

Critical flicker fusion (CFF) test for sedative effect of antidepressants

It is important to know in which direction and to what extent a drug affects cerebral arousal. Critical flicker fusion (CFF) is a most reliable method for measuring this particular quality of various drugs. A semi-automatic apparatus was used under standardized conditions, and double-blind technique was employed. Only acute experiments are described here. Dose-effect relationship can be demonstrated. The effect on cerebral arousal varies greatly from one antidepressant to another. Amitriptyline and doxepin were found to exert strong sedative effect, and amitriptyline-N-oxide an intermediate one, while imipramine and imipramine-N-oxide lacked this quality. Nomifensine in large doses has a significant stimulant action. Zimelidine in a low dose (75 mg) slightly, but significantly, lowered the CFF level, but at a dose of 150 mg no significant effect was obtained. At the doses 225 and 300 mg a slight increase was seen (about 2%). Various aspects of the findings are discussed in the paper.

Effects of benzodiazepines on psychomotor performance

1 The literature relating to the effects of benzodiazepines on psychomotor performance is critically reviewed. 2 The multiple and diverse psychomotor tests used are assessed according to their ability to demonstrate differences between drugs. 3 Three general conclusions are: (1) The speed with which simple acts of a repetitive nature are performed may be impaired by benzodiazepines. (2) learning and immediate memory will also be impaired. (3) there is relatively little indication that well established higher mental faculties are adversely involved.