Studies on the in vitro metabolism of compounds related to lysergic acid diethylamide (LSD)

Pharmacological and biotransformation studies of 1-acyl-substituted derivatives of d-lysergic acid diethylamide (LSD)

The ergoline d-lysergic acid diethylamide (LSD) is one of the most potent psychedelic drugs. 1-Acetyl-LSD (ALD-52), a derivative of LSD containing an acetyl group on the indole nitrogen, also produces psychedelic effects in humans and has about the same potency as LSD. Recently, several other 1-acyl-substitued LSD derivatives, including 1-propanoyl-LSD (1P-LSD) and 1-butanoyl-LSD (1B-LSD), have appeared as designer drugs. Although these compounds are assumed to act as prodrugs for LSD, studies have not specifically tested this prediction. The present investigation was conducted to address the gap of information about the pharmacological effects and mechanism-of-action of 1-acyl-substituted LSD derivatives. Competitive binding studies and calcium mobilization assays were performed to assess the interaction of ALD-52, 1P-LSD, and 1B-LSD with serotonin 5-HT₂ receptor subtypes. A receptorome screening was performed with 1B-LSD to assess its binding to other potential targets. Head twitch response (HTR) studies were performed in C57BL/6J mice to assess in vivo activation of 5-HT_2A (the receptor thought to be primarily responsible for hallucinogenesis). Finally, liquid chromatography/ion-trap mass spectrometry (LC/MS) was used to quantify plasma levels of LSD in Sprague-Dawley rats treated with ALD-52 and 1P-LSD. 1-Acyl-substitution reduced the affinity of LSD for most monoamine receptors, including 5-HT_2A sites, by one to two orders of magnitude. Although LSD acts as an agonist at 5-HT₂ subtypes, ALD-52, 1P-LSD and 1B-LSD have weak efficacy or act as antagonists in Ca²⁺-mobilization assays. Despite the detrimental effect of 1-acyl substitution on 5-HT_2A affinity and efficacy, 1-acyl-substitued LSD derivatives induce head twitches in mice with relatively high potency. High levels of LSD were detected in the plasma of rats after subcutaneous administration of ALD-52 and 1P-LSD, demonstrating these compounds are rapidly and efficiently deacylated in vivo. These findings are consistent with the prediction that ALD-52, 1P-LSD and 1B-LSD serve as prodrugs for LSD. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Metabolism of lysergic acid diethylamide (LSD): an update

Lysergic acid diethylamide (LSD) is the most potent hallucinogen known and its pharmacological effect results from stimulation of central serotonin receptors (5-HT₂). Since LSD is seen as physiologically safe compound with low toxicity, its use in therapeutics has been renewed during the last few years. This review aims to discuss LSD metabolism, by presenting all metabolites as well as clinical and toxicological relevance. LSD is rapidly and extensively metabolized into inactive metabolites; whose detection window is higher than parent compound. The metabolite 2-oxo-3-hydroxy LSD is the major human metabolite, which detection and quantification is important for clinical and forensic toxicology. Indeed, information about LSD pharmacokinetics in humans is limited and for this reason, more research studies are needed.

Dark Classics in Chemical Neuroscience: Lysergic Acid Diethylamide (LSD)

Lysergic acid diethylamide (LSD) is one of the most potent psychoactive agents known, producing dramatic alterations of consciousness after submilligram (≥20 μg) oral doses. Following the accidental discovery of its potent psychoactive effects in 1943, it was supplied by Sandoz Laboratories as an experimental drug that might be useful as an adjunct for psychotherapy, or to give psychiatrists insight into the mental processes in their patients. The finding of serotonin in the mammalian brain in 1953, and its structural resemblance to LSD, quickly led to ideas that serotonin in the brain might be involved in mental disorders, initiating rapid research interest in the neurochemistry of serotonin. LSD proved to be physiologically very safe and nonaddictive, with a very low incidence of adverse events when used in controlled experiments. Widely hailed by psychiatry as a breakthrough in the 1950s and early 1960s, clinical research with LSD ended by about 1970, when it was formally placed into Schedule 1 of the Controlled Substances Act of 1970 following its growing popularity as a recreational drug. Within the past 5 years, clinical research with LSD has begun in Europe, but there has been none in the United States. LSD is proving to be a powerful tool to help understand brain dynamics when combined with modern brain imaging methods. It remains to be seen whether therapeutic value for LSD can be confirmed in controlled clinical trials, but promising results have been obtained in small pilot trials of depression, anxiety, and addictions using psilocybin, a related psychedelic molecule.

The pharmacology of lysergic acid diethylamide: a review

Lysergic acid diethylamide (LSD) was synthesized in 1938 and its psychoactive effects discovered in 1943. It was used during the 1950s and 1960s as an experimental drug in psychiatric research for producing so-called "experimental psychosis" by altering neurotransmitter system and in psychotherapeutic procedures ("psycholytic" and "psychedelic" therapy). From the mid 1960s, it became an illegal drug of abuse with widespread use that continues today. With the entry of new methods of research and better study oversight, scientific interest in LSD has resumed for brain research and experimental treatments. Due to the lack of any comprehensive review since the 1950s and the widely dispersed experimental literature, the present review focuses on all aspects of the pharmacology and psychopharmacology of LSD. A thorough search of the experimental literature regarding the pharmacology of LSD was performed and the extracted results are given in this review. (Psycho-) pharmacological research on LSD was extensive and produced nearly 10,000 scientific papers. The pharmacology of LSD is complex and its mechanisms of action are still not completely understood. LSD is physiologically well tolerated and psychological reactions can be controlled in a medically supervised setting, but complications may easily result from uncontrolled use by layman. Actually there is new interest in LSD as an experimental tool for elucidating neural mechanisms of (states of) consciousness and there are recently discovered treatment options with LSD in cluster headache and with the terminally ill.

Pharmacokinetics of methylergometrine in the rat: evidence for enterohepatic recirculation by a linked-rat model

The pharmacokinetics of methylergometrine were investigated in the rat, with emphasis on the role of biliary excretion and enterohepatic recirculation in the overall disposition of the drug. A linked-rat model, where the bile from a rat receiving a constant rate of iv infusion of methylergometrine was allowed to flow into the duodenum of another rat, was used for the estimation of the degree of enterohepatic recirculation (EHC). The excretion of unchanged methylergometrine in the bile was estimated separately. Plasma protein binding and plasma-to-whole blood partitioning were also determined. Plasma clearance in control rats was 17.4 +/- 0.7 ml/min x kg for iv bolus and 15.4 +/- 0.7 ml/min x kg for iv infusion. The corresponding values in the bile-cannulated rats were significantly lower, 7.7 +/- 0.4 and 8.7 +/- 0.1 ml/min x kg, respectively. The lower clearance in the bile-cannulated rats was caused mainly by a lower free fraction in plasma, fu (0.11 +/- 0.01), in this group compared with the control group (0.19 +/- 0.0.03). The unbound volume of distribution at steady state (Vssu) was only 6.5 liters/kg in the bile-cannulated rats, compared to 14.7 liters/kg in control rats, suggesting that under steady-state conditions, more than 50% of the methylergometrine is conjugated or residues in the hepatobiliary loop, either as a conjugate or unchanged. The fraction of unchanged methylergometrine excreted in the bile was less than 0.3% of the given dose, while the fraction of the dose being reabsorbed during one cycle (freabs) was 8.4 +/- 6.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Methylergometrine, an active metabolite of methysergide

In conscious dogs methysergide (MS) caused constriction of the saphenous vein at about 3000 times lower doses than methylergometrine (MT) when infused locally, but it elicited only a short-lasting venoconstrictor response when injected systemically intravenously. MS and MT proved to be equally active venoconstrictor agents when administered orally. Analysis of canine plasma by high-performance liquid chromatography showed that after both oral and intravenous administration of MS large amounts of MT appeared in the plasma, whereas only low and transient levels of MS could be detected. It is suggested that one of the first steps in metabolism of MS is demethylation at position 1 of the indole, leading to the formation of MT, which may be a main active principle of the therapeutic effectiveness of MS in the interval treatment of migraine headache.

Enzymic formation of dehydrogenated and hydroxylated metabolites from lysergic acid diethylamide by rat liver microsomes

1. The metabolism of lysergic acid diethylamide (LSD) was studied using rat liver microsomes, and two minor metabolites were obtained in addition to lysergic acid ethylamide and N6-desmethyl-lysergic acid diethylamide (nor-LSD) which were reported previously. 2. One of the metabolites was identified as lysergic acid ethylvinylamide, apparently formed by dehydrogenation of a diethylamide group in the side chain at the 8-position, and the other as the phenol 13-hydroxy-LSD. 3. The formation of both lysergic acid ethylamide and lysergic acid ethylvinylamide was similarly induced by pretreatment of rats with either phenobarbitone sodium or 3-methylcholanthrene, while nor-LSD formation was induced only by phenobarbitone and that of 13-hydroxy-LSD only by methylcholanthrene.