Anesthesiology
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Anesthetic requirement in redheads is exaggerated, suggesting that redheads may be especially sensitive to pain. Therefore, the authors tested the hypotheses that women with natural red hair are more sensitive to pain and that redheads are resistant to topical and subcutaneous lidocaine. ⋯ Red hair is the phenotype for mutations of the melanocortin-1 receptor. Results indicate that redheads are more sensitive to thermal pain and are resistant to the analgesic effects of subcutaneous lidocaine. Mutations of the melanocortin-1 receptor, or a consequence thereof, thus modulate pain sensitivity.
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Some patients treated with ondansetron for postoperative nausea and vomiting do not respond to therapy. One possible mechanism for this failure is ultrarapid drug metabolism via the cytochrome P-450 system, specifically the enzyme 2D6 (CYP2D6). Ultrarapid metabolism is seen in patients with multiple functional copies (>/= 3) of the CYP2D6 allele. This study was designed to determine whether patients who were given prophylactic ondansetron and had multiple CYP2D6 alleles had an increased rate of postoperative nausea and vomiting. ⋯ Patients with three copies of the CYP2D6 gene, a genotype consistent with ultrarapid metabolism, or both have an increased incidence of ondansetron failure for the prevention of postoperative vomiting but not nausea.
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Some studies suggest that behavioral complications of cholestasis, such as fatigue and pruritus, may be associated with altered neurotransmission in the brain. Because inhaled anesthetics primarily act on ion channels and receptors on the neuronal cell membrane and alter synaptic transmission in the central nervous system, it is possible that altered sensitivity to inhaled anesthetics may occur in cholestatic patients. Therefore, the authors compared the minimum alveolar concentration (MAC)-awake of desflurane in obstructive jaundiced patients with the MACawake in nonjaundiced patients. ⋯ The MACawake of desflurane is reduced in obstructive jaundiced patients compared with nonjaundiced controls.
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Succinylcholine remains the standard neuromuscular blocking drug for tracheal intubation in emergency situations. The short duration of action is due to its rapid hydrolytic degradation by butyrylcholinesterase (plasmacholinesterase). Multiple variants of this enzyme are known (A, F, S, H, J, K variants) with different effects on enzyme activity. This study was undertaken to evaluate the use of molecular genetic methods in patients with clinically prolonged neuromuscular block. ⋯ Variations in the genetic sequence of butyrylcholinesterase are frequent in patients with prolonged duration of action of succinylcholine. Direct sequencing of the whole butyrylcholinesterase gene is an appropriate method for genotyping and, accordingly, should be used in future clinical studies with drugs metabolized by this enzyme (e.g., succinylcholine, mivacurium).