atorvastatin + phenytoin

**Atorvastatin + phenytoin** is a pharmacological combination of two small molecule drugs: atorvastatin, an HMG-CoA reductase inhibitor (statin) used primarily to lower cholesterol and reduce cardiovascular risk, and phenytoin, an antiepileptic medication primarily used for the management and prevention of seizures. Atorvastatin acts by inhibiting hepatic cholesterol synthesis via competitive inhibition of HMG-CoA reductase, resulting in upregulation of LDL receptors and increased clearance of LDL cholesterol. Phenytoin acts mainly by stabilizing neuronal membranes and reducing repetitive neuronal firing by promoting sodium efflux from neurons. When administered together, phenytoin, a potent CYP3A4 inducer, reduces the serum concentration and efficacy of atorvastatin by increasing its metabolic clearance[1][2][3][4][5][6][7].