Possible involvement of μ- and κ-opioid receptors and cannabinoid type 1 receptors (CB1) into the mechanism of analgesic activity of the experimental drug product "Thiowurtzine, (capsule 120 mg)" synthesized on the basis of active pharmaceutical substance 4-(3,4-dibromthiophencarbonyl)-2,6,8,12-tetraacethyl-2,4,6,8,10,12hexaazatetracyclo [5,5,0,0,0]dodecane was studied in vivo using the hot plate test and acetic acid writhing test. The involvement of κ-opioid receptors and noninvolvement of μ-receptors and CB1 receptors in the mechanism of thiowurtzine analgesia were demonstrated. The mechanism of interaction of the test analgesic with opioid receptors differs from that of the reference drug tramadol. The interaction of thiowurtzine with serotonergic, GABAergic, and muscarinic cholinergic neurotransmitter systems was studied in vivo using pharmacological analyzers. The absence of muscarinic cholinolytic effect of thiowurtzine was demonstrated in the model of arecoline-induced tremor. The central serotonin-blocking activity of the analgesic was revealed in the model of 5-hydroxytryptophan hyperkinesis in mice. Anticonvulsant activity was demonstrated in the corazol convulsions test, which attested to the presence of a GABAergic component. The mechanism of central analgesia caused by the drug product "Thiowurtzine, capsule 120 mg" appeared to be polymodal. The antinociceptive activity of the analgesic was comparable to that of tramadol.