WebJun 1, 2016 · As the dose or concentration of phenytoin increases, the clearance rate (Cl) decreases as the enzyme approaches saturable conditions: Cl = V max / (K m + C). This is the reason concentrations increase disproportionately after a phenytoin dosage increase. WebPhenytoin clearance tends to decrease with increasing age (20% less in patients over 70 years of age relative to that in patients 20-30 years of age). Phenytoin dosing …
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WebMay 1, 2006 · MECHANISMS OF INTERACTION Hepatic metabolism. The most common cause of drug interactions with phenytoin is induction of the cytochrome P-450 isoenzymes CYP2C, CYP2D, and CYP3A subfamilies and UDP-glucuronosyltransferase. 1 Metabolism of drugs that are substrates for these isoenzymes can be enhanced, thereby decreasing their … WebPhenytoin clearance is decreased slightly in elderly patients and lower or less frequent dosing may be required [see Clinical Pharmacology (12.3)]. 2.8 Dosing during Pregnancy Decreased serum concentrations of phenytoin may occur during pregnancy because of altered phenytoin pharmacokinetics. Periodic measurement of serum phenytoin how to take pictures like a fashion blogger
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WebWe withdrew phenytoin from 17 inpatients maintained on combination therapy with carbamazepine for complex partial seizures and analyzed seizure occurrence in relation … WebClearance was typically increased by 138% (95% confidence interval, 93-183%) in patients taking phenytoin. The effect of vecuronium was well described using a sigmoid Emax model. The concentration of vecuronium giving 50% twitch depression was increased 124% (45-202%) in patients taking phenytoin. WebPhenytoin's mechanism involves blocking of sodium channels and, therefore, represents an alternative mechanism to the action of barbiturates (i.e., phenobarbital) and benzodiazepines, which both act on chloride channels. The usual loading dose is 20 mg/kg for phenytoin or 20 mg phenytoin-equivalents/kg for fosphenytoin. how to take pictures in spiderman pc