Acute cardiovascular fatalities following cannabis use

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Abstract

We report six cases of possible acute cardiovascular death in young adults, where very recent cannabis ingestion was documented by the presence of tetrahydrocannabinol (THC) in postmortem blood samples. A broad toxicological blood analysis could not reveal other drugs. Similar cases have been reported in the literature, but the toxicological analysis has been absent or limited to urine samples, which represent a much broader time window for cannabis intake. This paper presents six case reports, where cannabis alone was detected in blood. Further, an overview over previously published cases, clinical trials and possible patho-physiological mechanisms are presented.

Introduction

Different preparations of the plant Cannabis sativa are widely used around the world for their euphoric effects, making cannabis the most frequent drug of abuse, second only to alcohol in the western world. The most commonly used preparations are marijuana and hashish, which in this paper will be referred to as cannabis. Cannabis toxicity is regarded to be low [1]. By extrapolation from animal experiments, the ratio of lethal to effective (intoxicating) dose is estimated to be in the order of thousands to one [2]. Acute cannabis toxicity is briefly, if at all, mentioned in comprehensive textbooks about drug abuse. However, several case reports of both coronary and cerebral ischaemia related to cannabis intake have been published, since the seventies [3], [4], [5], [6], [7], [8]. Many studies reported in the literature lack the determinations of tetrahydrocannabinol (THC) or THC metabolites in blood, actually demonstrating the recent intake of cannabis.

After smoking a “regular” dose of cannabis (usually containing about 20 mg THC), blood concentration of THC rises quickly and reaches peak levels before the end of the smoking period. The immediate distribution from blood to tissues is also fast and blood THC levels quickly drop to <10% within 2 h. As a consequence, THC can only be detected in blood by standard methods, depending on dose and analytical cut-off, for 4–12 h after intake. Subjective feeling of euphoria is associated with whole blood levels from 2 μg/l and higher. Whole blood levels 1 h after smoking 20–25 mg THC will typically be in the range 5–10 μg/l [9].

Section snippets

Case 1

A 39-year-old male was found dead sitting in his living room with the TV-set on. He did not have any previous record of heart disease, but had a recent sick leave from his job as a fisherman because of shoulder pain. On the day of his death, a co-worker had driven him home from work because of worsening of his shoulder pain. The autopsy revealed findings compatible with an older and a recent heart infarction as well as hypertrophied heart. There was widespread atheromatosis in the coronary

Materials and methods

The National Institute for Forensic Toxicology (NIFT) is the national laboratory for forensic pharmacological and toxicological analyses in Norway. Blood, urine and other biological samples from almost every medicolegal autopsies performed in Norway, are sent to NIFT together with the preliminary results from the autopsies. Illegal drugs, including cannabis, are part of the standard analytical program for all autopsy samples. Postmortem blood is screened for amphetamines, benzodiazepines,

Results

In the period from 1995 to 1999, cannabis was detected in a total of 180 blood samples out of almost 10,000 autopsy cases analysed. In 145 cases, there were also other toxicological findings (prescribed medication or illicit drugs) that could have contributed to the death. The remaining samples (35) contained THC as the major toxicological finding, although low alcohol concentrations (below 0.05%) or benzodiazepines in the therapeutic concentration range were present in some cases. These 35

Discussion

Cardiovascular effects are the most consistent physiological findings after acute cannabis administration. Significant tachycardia, conjunctival injection and increased limb blood flow with postural hypotension have been reported. These effects are likely to be mediated via β-adrenergical stimulation and possibly also a parasympathetic nervous system blockade [12], [13], [14], [15]. A catecholamine increase will lead to an increased oxygen demand in the myocardium, constituting a potential

Conclusions

Several reports of acute cardiovascular episodes associated to cannabis use have been published in the last 20 years and underlying patho-physiological mechanisms have been discussed. Cannabis is generally considered to be a drug with very low toxicity. In this paper, we report six cases where recent cannabis intake was associated with sudden and unexpected death. An acute cardiovascular event was the probable cause of death. In all cases, cannabis intake was documented by blood analyses. To

Acknowledgements

We would like to thank the pathologists Åshild Vege, Inge Morild, Rolf Steen, Elin Mortensen and Vidar Isaksen, who performed the autopsies, for their collaboration in the preparation of this manuscript.

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