British journal of anaesthesia
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Comparative Study
Comparative pharmacology of the ketamine isomers. Studies in volunteers.
The clinical and electroencephalographic (EEG) effects of the individual ketamine isomers were compared with the racemic mixture in five volunteers who received each drug on a separate occasion. Racemic ketamine 275 +/- 25 mg, s(+) ketamine 140 +/- 21 mg or R(-) ketamine 429 +/- 37 mg produced an anaesthetic state lasting 6 +/- 2 min (mean +/- SD). However, the EEG evaluation of the R(-) isomer revealed less overall slowing, and an absence of the large slow wave complexes produced by the S(+) isomer and the racemic mixture. ⋯ The serum ketamine concentrations associated with regaining consciousness and orientation were consistent with an S(+):R(-) isomer potency ratio of 4:1. In terms of their ability to impair psychomotor function, the S(+):R(-) potency ratio varied from 3:1 to 5:1. After comparable degrees of CNS depression, we conclude that the more potent S(+) isomer of ketamine was associated with a more rapid recovery of psychomotor skills than the currently used racemic mixture.
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Randomized Controlled Trial Comparative Study Clinical Trial
Pattern of CNS recovery following reversal of neuromuscular blockade. Comparison of atropine and glycopyrrolate.
Recovery from anaesthesia was compared, in a group of patients (n = 25) receiving a mixture of glycopyrrolate and neostigmine (to reverse non-depolarizing neuromuscular blockade), with recovery in a group of patients (n = 25) receiving an atropine-neostigmine mixture. Recovery following anaesthesia was more rapid in the patients receiving the glycopyrrolate-neostigmine mixture.
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Atropine and glycopyrrolate were compared in a mixture with neostigmine for reversal of neuromuscular blockade in patients undergoing open heart surgery. In patients not receiving beta-blocking drugs, glycopyrrolate was shown to possess advantages over atropine in terms of a lower initial increase in heart rate, better protection against the muscarinic effects of neostigmine, and smaller increases in rate-pressure product. The concomitant administration of beta-adrenergic blocking therapy significantly attenuated the effect of reversal on heart rate and the differences between atropine and glycopyrrolate were not significant. There was no difference in the incidence of arrhythmias between patients who received beta-blocking drugs and those who did not.
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Blood cyanide (HCN) or plasma thiocyanate (SCN) concentrations, or both, were measured in 30 patients (ages 11 months-72 yr) receiving sodium nitroprusside (SNP) for 12-314 h. Sequential measurements in three of these patients (infused 5, 12 and 13 days) showed that HCN concentrations varied with dose rate, while SCN concentrations increased linearly with increasing SNP dose. ⋯ Likewise, the SCN results (30--880 mumol litre-1) confirmed the close relationship between plasma concentrations and the total SNP dose (0.44-32.9 mg kg-1; y = 24.6x + 74.9; r = 0.95, n = 51, P less than 0.001). Therefore, we suggest that, to avoid SCN toxicity (plasma SCN greater than 1.75 mumol litre-1), in the absence of SCN monitoring, the total SNP dose should be less than 70 mg kg-1 in patients with normal renal function.