The Identification of Barbiturate Drugs in Gastric Contents and Urine.

Cases are admitted from time to time to most large hospitals in a state of coma or semi-coma in which the differential diagnosis includes overdosage with the barbiturate series of narcotic drugs. It is often important to confirm or exclude this factor as quickly as possible. Standard methods of analysis (e.g., the Stas-Otto process, Smith, 1934a), although ultimately giving accurate quantitative results, are time-consuming. An endeavour has been made to evolve a more rapid method of analysis which is sufficiently delicate to give an answer to the question of whether -or not barbiturate poisoning plays a significant part in the clinical condition of the patient. The method in our hands takes about three hours to perform and is based upon the facts that (1) the barbiturate drugs, being derived from barbituric acid, are either the acid derivatives, e.g., diethylbarbituric acid (barbitone), or their sodium salts, e.g., sodium diethylbarbiturate (soluble barbitone). (2) When in aqueous solution they can be changed from one form to the other by making the pH acid or alkaline. (3) The barbituric acid derivatives are only slightly soluble in water but are readily soluble in ether, whereas their sodium salts are readily soluble in water and almost insoluble in ether. As part of any ingested barbituric acid is excreted unchanged in the urine, at least 100 ml. of urine are collected and examined in all cases. Unless the state of coma is known to have lasted for a long time, the gastric contents are aspirated and examined as well.