Barbiturates physiological effects

All the barbiturates possess the properties of CNS depressants. Thus, in moderate doses they produce a drunken euphoric state. Similar to alcohol, barbiturates may produce a loss of motor coordination, a staggering gait, and slurred speech. Loss of emotional control and behavioral disinhibition arc also characteristic cfTccts. Sedation and sleep are produced by increased doses, and higher doses produce surgical anesthesia. Physiological effects include respiratory depression, which is responsible for most of the overdose deaths associated with barbiturates. In addition some depression of heart rate, blood pressure, and gastrointestinal activity is noted at higher doses. 

The victim s mouth should be washed out with copious amounts of water, atropine should be administered to control salivation. Barbiturates are used to control convulsions calcium gluconate may be used to control some physiologic effects. Phenoxybenza-mine and propranolol have been used experimentally to block a- and jS-adrenergic receptors. Life-support therapy may be used to maintain respiration and other vital functions. 

Medications can cross the placenta and have an adverse effect on the fetus. The fetus has an immature metabolism and a slow excretion rate that can cause a pooling of the medication. Depending on the physiological effect of the medication, the fetus can be addicted to the medication and go through withdrawal after birth. This can occur with alcohol, barbiturates, and narcotics. 

Structural features of the barbiturate molecule which are required for its hypnotic, convulsant, and/or anticonvulsant properties have been summarized by Vida and Gerry,381 and numerous studies were devoted to physiological effects and pharmacological mechanisms of action of barbiturates in relation to chemical and stereochemical factors. Some recent articles and reviews are suggested on this fascinating and still incompletely elucidated subject.382 Clearly, the history of barbiturates383 has many paragraphs yet to be written. 

What is a barbiturate What are the physiological effects of barbiturates ... 

Figure 4.10. Structure of sodium thiopental (left). This compound is a derivative of barbituric acid, a compound first prepared by von Baeyer as shown in Scheme 4.1. While barbituric acid itseif is devoid of physiological effects, many derivatives, such as phenobarbital (right), have an important history as drugs, as detailed in the text...

GNS depressants are drugs that decrease brain activity, resulting in both behavioral and physiological changes. The effects of alcohol on coordination, speech, and cognitive functions are familiar to most people. The effects of barbiturates are similar to alcohol. In low doses, barbiturates act as sedatives increased doses have a hypnotic or sleep-inducing effect and stiU larger doses have anticonvulsant and anesthetic activity, and can lead to respiratory depression, coma, and death. Barbiturate addicts... 

During a study of the effect of 1- and 3-substitution on the physiological properties of the barbiturates, it was found that the 1 -diethylaminoethyl-3-benzyl derivative of allobarbital (XXVI) has pronounced analgesic and antipyretic activity, in addition to a sedative effect. The compound has hypotensive action, but is not a hypnotic [167]. 

The duration and even the intensity of action of lipid-soluble drugs is limited mainly by their rates of metabolism. For example, there are marked species, strain and, in rats and mice, sex differences in the duration of the hypnotic effect of most barbiturates, but these differences are caused mainly by differences in the rate of metabolism of the barbiturates rather than by differences in the receptor sites. Similarly, the duration of action of these barbiturates may be shortened or prolonged by physiological alterations and by administration of other drugs, but again many of these effects are caused by alterations in the rate of metabolism of the drugs, rather than alterations in the receptor sites. 

---