Barbiturates, antagonistic effects

The antagonistic effects of sodium pentothal on the blood pressure and the respiratory effects of chlordan are illustrated in Figure 1, C. The intermittent severe tremors with concomitant Cheyne-Stokes type of respiration produced by the injection of chlordan were decreased or entirely abolished, and both the respiratory rate and depth were restored to near normal. A dose of barbiturate sufficient to diminish the tremors appreciably and to restore the respiration to normal also produced a temporary drop of 10 to. 40 mm. of mercury in blood pressure. 

Interestingly, it does not show any antagonistic effect toward barbiturate or general anaesthetic depression. Nalorphine exerts its effect on the circulatory disturbances thereby reversing the effects of morphine. It is formd to cause depression in the respiratory activity itself, that may potentiate the prevailing depression produced by morphine. 

The short-acting clomethia2ole [533-45-9] (1), sometimes used as therapy for sleep disorders ia older patients, shares with barbiturates a risk of overdose and dependence. Antihistamines, such as hydroxy2iae [68-88-2] (2), are also sometimes used as mild sedatives (see HiSTAMlNES AND HISTAMINE antagonists). Antidepressants and antipsychotics which have sedative effects are used to treat insomnia when the sleep disorder is a symptom of some underlyiag psychiatric disorder. 

Combinations of barbiturates and benzodiazepine tranquilizers or even antihistaminergics having sedative properties are sometimes used. Furthermore, infusion of anesthetics can be used to provide long-term anesthesia for intensive care medicine. The antagonist flumazenil (18) is available to reverse the effects of anesthetics of the benzodiazepine class. 

The antidotal action of the barbiturates is probably limited to the effects of chlordan on the nervous system. They most likely have no beneficial antagonistic action against the delayed parenchymatous degenerative changes produced by chlordan (4). Therefore, they are primarily only of possible value in acute poisoning in which severe stimulation of the central nervous system may be the primary cause of death. 

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