Oral forms of the oxime HI-6: a study of pharmacokinetics and tolerance after administration to healthy volunteers

New pharmaceutical formulations of the oxime HI-6 as sustained-release and conventional tablets were studied in healthy volunteers. Twenty-six subjects, divided into 3 groups, received 3784 mg or 7568 mg doses of HI-6 conventional tablets or 4027 mg of the oxime in the form of sustained-release tablets. Peak plasma concentrations of HI-6 were reached within 0.6 h (10.2 mumol/l) and 1.6 h (21.4 mumol/l) following the ingestion of conventional tablets. Elimination half-lives were similar (1.7 h and 1.3 h) and the respective urinary recoveries amounted to 3.2% and 2.9%. After the administration of sustained-release tablets of HI-6, maximal concentration (8.8 mumol/l) was attained in 2.2 h, elimination half-life was 1.9 h and 4.2% of the dose was excreted unchanged in urine. Undesirable side effects were not reported by the subjects or revealed by clinical or laboratory tests. The results indicate low bioavailability of the oral formulations of HI-6 in man.