Sigmodal (Rectidon) is a barbiturate derivative. It has sedative, hypnotic and anticonvulsant properties, and was used in surgical anaesthesia in the 1950s, and frequently appeared in drug mixtures in the 60s.
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It was never widely used compared to better known barbiturates such as thiopental, and has now been replaced by newer drugs with a better safety profile.
References
↑"[Our experiences with rectidon basal anesthesia]" (in german). Zentralblatt für Gynakologie74 (48): 1895–6. 1952. PMID13050081.
↑"[On rectidon basis narcosis]" (in german). Die Medizinische20 (47): 1503–4. November 1952. PMID13024592.