Arch. Toxicol. 36, 83--88 (1976) Archives of TOXICOLOGY 9 by Springer-Verlag 1976 Administration of Obidoxime Tablets to Man Plasma Levels and Side Reactions G. A. Simon 1., M. S. Tirosh 2, and H. Edery 1 Israel Institute for Biological Research, Tel-Aviv University Medical School, Ness Ziona, Israel 2 Clinical Toxicology Unit, Chaim Sheba Medical Center, Tel-Hashomer Abstract. Twenty-four male volunteers were given obidoxime tablets in quanti- ties ranging from 1.84-3.58 g in a single dose, or 7.36 g divided into 4 equal doses. With the lowest dose, average peak plasma level of the drug was 1.9 ~g/ml and after the highest single dose it was 5.6 ~g/ml, both attained 1.5 h after administration. In the multiple-dosed individuals, plasma levels of the oxime increased gradually following each additional dose, reaching a peak of 3.5 ~g/ml after the last dose. Thirteen individuals complained of one or more of the following side effects: pallor, nausea, pyrosis, headache, generalized weakness, sore throat, and pares- thesia of the face muscles. Activities of blood cholinesterase, glutamic oxalacetic transaminase, glu- tamic pyruvic transaminase, as well as hematocrit values, heart rate, and blood pressure were not affected. It is postulated that due to the undesirable side effects, the general use of obidoxime tablets should not be recommended. However, prophylactic oral treatment with obidoxime could be considered for persons at high risk of organo- phosphate poisoning or when parenteral administration might not be feasi- ble. Key words: Obidoxime -- Tablets --Plasma levels - Side reactions. Zusammenfassung. Vierundzwanzig m~innliche Freiwillige erhielten Obidoxim- tabletten in Einzeldosen von 1,84--3,68 g oder 7,36 g verteilt in vier gleichm/i/3i- gen Dosen. In der Gruppe mit der niedrigsten Dosierung war der Mittelwert der H6chstkonzentrationen im Plasma 1,9 ~g/ml, und nach der h6chsten Einzeldo- sis 5,6 ~g/ml. In beiden F~illen wurden die h/Schsten Werte 1,5 Std nach Ein- nahme der Tabletten erreicht. Bei den Teilnehmern mit der wiederholten Dosie- rung wurde, nach jeder zus/itzlichen Tabletteneinnahme, die Plasmakonzentra- tion erh6ht, und erreichte einen H6hepunkt von 3,5 ~g/ml nach der letzten Applikation. * To whom offprint requests should be sent