Dreaming, fenfluramine, and vitamin C

Cardiotoxic effects of fenfluramine hydrochloride on isolated cardiac preparations and ventricular myocytes of guinea-pigs

The cardiotoxic effects of fenfluramine hydrochloride on mechanical and electrical activity were studied in papillary muscles, Purkinje fibres, left atria and ventricular myocytes of guinea-pigs. Force of contraction (f(c)) was measured isometrically, action potentials and maximum rate of rise of the action potential (V(max)) were recorded by means of the intracellular microelectrode technique and the sodium current (I(Na)) with patch-clamp technique in the cell-attached mode. For kinetic analysis (S)-DPI-201-106-modified Na(+) channels from isolated guinea-pig ventricular heart cells were used. Fenfluramine (1 - 300 microM) produced negative chronotropic and inotropic effects; additional extracellular Ca(2+) competitively antagonized the negative inotropic effect. Fenfluramine concentration-dependently reduced V(max) and showed tonic blockade of sodium channels, shortened the action potential duration in papillary muscles and Purkinje fibres. In cell-attached patches, fenfluramine decreased I(Na) concentration-dependently (10 - 100 microM), frequency-independently (0.1 - 3 Hz; 30 microM). The h(infinity) curve was shifted towards hyperpolarizing direction. At 30 microM, fenfluramine blocked the sodium channel at all test potentials to the same degree, and neither changed the threshold and reversal potentials nor the peak of the curve. No effect on single channel availability, but a significant decrease in mean open times and increase in mean closed times was observed. Mean duration of the bursts decreased and number of openings per record increased with increasing drug concentration. It is concluded that the effect on I(Na) plays an important role in the cardiotoxicity of fenfluramine in addition to primary pulmonary hypertension and valvular disorders.

Drug-induced nightmares

OBJECTIVE

To compile and assess the English-language literature on drug-induced nightmares, excluding nightmares secondary to drug withdrawal or drug-associated night terrors.

DATA SOURCES

Published articles, letters, case reports, and abstracts in English were identified by MEDLINE (1966-May 1998) searches using the search term nightmares, chemically induced. Additional articles were obtained from bibliographies of retrieved articles.

DATA EXTRACTION

All case reports of drug-induced nightmares were evaluated using the Naranjo algorithm for causality. Clinical studies of drugs that reported nightmares as an adverse effect were assessed for frequency of occurrence.

DATA SYNTHESIS

Nightmares, defined as nocturnal episodes of intense anxiety and fear associated with a vivid, emotionally charged dream experience, are generally classified as a parasomnia. Possible pharmacologic mechanisms for drug-induced nightmares, such as REM suppression and dopamine receptor stimulation, are reviewed. However, the vast majority of therapeutic agents implicated in causing nightmares have no obvious pharmacologic mechanism.

CONCLUSIONS

Assessing causality with an event such as a nightmare is difficult because of the high incidence of nightmares in the healthy population. Using qualitative, quantitative, and possible pharmacologic mechanism criteria, it appears that sedative/hypnotics, beta-blockers, and amphetamines are the therapeutic modalities most frequently associated with nightmares. These drug classes have a plausible pharmacologic mechanism to explain this effect. Dopamine agonists also have evidence of causality, with dopamine receptor stimulation as a possible pharmacologic mechanism.

Alcohol and drowning--the Geelong experience, 1957-1980

The resident population in the Geelong coronial district is approximately 250 000 persons and has almost doubled since 1957. The autopsy rate for all persons dying by accident is virtually 100 per cent, with specimens being taken for blood alcohol concentration on all such deaths. The ‘Geelong Experience’ concerning alcohol and drowning is based on the post-mortem findings and the history of the events which surrounded 238 fatal submersions during the 24-year period, 1957 to 1980. Males greatly predominated over females and 139 drownings occurred in males aged 15 years and older. No female had an autopsy blood alcohol concentration (BAC) greater than 0.08 per cent (18 mmol/L) whereas such concentrations were present at autopsy in 35 per cent of all drowned males aged 15 years and older. Of the deceased males in the 30 to 64 years age group, 45 per cent of those submersed while swimming or surfing and 75 per cent of those falling or slipping into water had autopsy BACs greater than 0.150 per cent (33 mmol/L). Of these latter males, 8 (that is, 33 per cent) had autopsy BACs greater than 0.25 per cent (55 mmol/L).

Effects of the phenethylamine derivatives, BL-3912, fenfluramine, and Sch-12679, in rats trained with LSD as a discriminative stimulus

Six rats were trained to discriminate the effects of LSD (100 micrograms/kg) and saline in a two-lever choice task. They were then tested with each of three phenethylamine derivatives, BL-3912 (2,5-dimethoxy-4-methyl-alpha-ethyl-phenethylamine), fenfluramine (N-ethyl-alpha-methyl-m-(trifluoro-methyl)phenethylamine), and Sch-12679 (N-methyl-1-phenyl-7,8-dimethoxy-2,3,4,5-tetra-hydro-3-benzazepine maleate). Fenfluramine and Sch-12679 yielded intermediate results, i.e., responding was not fully appropriate for either training condition while BL-3912 substituted completely for LSD. The LSD-like effects of each of the drugs were antagonized by pretreatment with BC-105, a serotonergic antagonist known to block the stimulus effects of indole and phenethylamine hallucinogens. The present data together with consideration of the known clinical effects of BL-3912, fenfluramine, and Sch-12679 are consistent with the following conclusions: (1) a variety of drugs may substitute in whole or in part for LSD in LSD-trained rats, and (2) even complete substitution of a drug for LSD in the rat is not necessarily associated with the production by that drug of hallucinations in man.