Articles: anesthetics.
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J. Pharm. Pharmacol. · Jan 1988
Myoclonic seizures in the mouse induced by alphaxalone and related steroid anaesthetics.
The anaesthetic steroids alphaxalone. 5 beta-alphaxalone and pregnanolone each caused myoclonic jerks in mice in a dose-related manner between 4 and 16 mg kg-1 i.v. There was no loss of righting reflex at these doses. The veterinary product Saffan, which contains alphaxalone and alphadalone, also caused myoclonic jerks at 2 mg kg-1 i.v., and a loss of righting reflex at doses of 4 mg kg-1 and above. These effects appear to be unrelated to the wide spectrum of potencies at the GABAA receptor complex of the three individual steroids as potentiators of muscimol, or as attenuators of picrotoxin.
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The toxicity of local anesthetic agents can be divided into two categories: (1) systemic toxic reactions due usually to an accidental intravascular injection and (2) local tissue toxicity. The systemic toxicity of local anesthetic agents is primarily characterized by CNS excitation and convulsive activity. The cardiovascular system is more resistant to the toxic actions of local anesthetics. ⋯ However, large doses of chloroprocaine solutions administered intrathecally have been associated with prolonged sensory-motor deficits in a few patients due probably to the low pH and presence of sodium bisulfite in the chloroprocaine solutions. In general, local anesthetic agents are relatively safe if administered properly. However, as with any pharmacological agents, local anesthetics may cause severe toxic reactions due to the improper use of these drugs.
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In regional anesthesia sudden and severe complications occur from time to time and may rapidly turn into life threatening situations. Their rarity might well be their most vicious characteristic. Therefore, awareness of the possible complications, careful preparation to cope with them, vigilance enabling prompt recognition of their occurrence and quick administration of the appropriate treatment are all essential for a safe practice of regional anesthesia. The routine use of pulse oximetry is now strongly recommended.
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The prevention of toxic accidents due to local anesthetics is simple. The doses used must be carefully selected according to the drug chosen, the areas to be anaesthetized, and whether or not the local anaesthetic solution contains adrenaline. Continuous infusions of local anaesthetics should be used with great care. ⋯ Using a test dose of adrenaline to detect accidental vascular puncture is simple, but not foolproof (patients treated with beta-blockers, obstetrical cases). The slow injection of local anaesthetics is the best way of preventing this type of accident. Finally, the technique for intravenous regional anaesthesia must be very strict.