Does phenytoin induce metabolism of other drugs?

Phenytoin has complicated pharmacokinetics, which make neonatal use complex. It is highly protein bound, so free levels can be difficult to achieve in newborns with renal or hepatic issues. It also induces hepatic metabolism of many other medications, including phenobarbital which is often concurrently administered.

Can phenytoin affect liver function?

Phenytoin is an anticonvulsant that in rare cases can cause acute idiosyncratic drug-induced liver disease that can be severe or even fatal. The liver injury caused by phenytoin appears to be due to a hypersensitivity reaction and resembles cases of immunoallergic hepatotoxicity.

How is phenytoin metabolized?

Phenytoin is metabolized by cytochrome P450 (P450) enzymes primarily to 5-(p-hydroxyphenyl-),5-phenylhydantoin (HPPH), which may be further metabolized to a catechol that spontaneously oxidizes to semiquinone and quinone species that covalently modify proteins.

Is phenytoin a liver enzyme inducer?

Phenytoin is a microsomal enzyme inducer.

Is phenytoin a CYP450 inducer?

Phenobarbital, phenytoin, primidone and carbamazepine are potent inducers of cytochrome P450 (CYP), epoxide hydrolase and uridine diphosphate glucuronosyltransferase (UDPGT) enzyme systems; oxcarbazepine is a weak inducer of CYP enzymes, probably acting on a few specific isoforms only.

How does phenytoin affect other drugs?

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. Metabolism of drugs that are substrates for these isoenzymes can be enhanced, thereby decreasing their serum concentrations.

What is the contraindications for phenytoin?

Phenytoin is contraindicated in those patients who are hypersensitive to phenytoin or other hydantoins. Antiepileptic drugs (AEDs), including Dilantin, may increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication.

Is valproic acid hepatotoxic?

One interesting aspect of valproic acid toxicity is the phenomenon of valproate-induced hepatotoxicity. This is indeed a rare event, although it is important to note that it can often lead to death. The underlying mechanism of injury at the subcellular level involves direct disruption of mitochondrial processes.

Is phenytoin a CYP inducer?

Inducers of CYP3A4 include phenobarbital, phenytoin, rifampicin, St. John’s Wort and glucocorticoids.

What happened when phenytoin given with TCAs?

Phenytoin may act through a similar mechanism as lidocaine, although experimental studies suggest that it does not compete directly for the same sodium channel binding site as TCAs. Allosteric modulation of the TCA binding site may occur in the setting of phenytoin use.

What are hepatic enzyme inducing medicines?

anticonvulsants, particularly phenytoin, carbamazepine, phenobarbitone and primidone. spironolactone.