Lipitor 40mg Tablet

Atorvastatin 40mg

Pharmacology
Mechanism of Action
HMG-CoA reductase inhibitor; inhibits rate-limiting step in cholesterol biosynthesis by competitively inhibiting HMG-CoA reductase

Absorption
Bioavailability: 14% (parent drug)
Onset: 3-5 days
Duration: 48-72 hr
Peak serum time: 1-2 hr
Maximum effect: 2 weeks

Distribution
Protein bound: 98%
Vd: 381 L

Metabolism
Via hepatic P450 enzyme CYP3A4
Metabolites: Ortho- and parahydroxylated derivatives and beta-oxidation product (inactive)

Elimination
Half-life: 14 hr
Dialyzable: No (HD)
Excretion: Mainly via bile; urine (2%)

Pharmacogenomics
SLCO1B1 (OATP1B1) CC genotype significantly increases AUCs of parent drug and metabolites compared with the CT or TT genotypes
This polymorphism is proposed to reduce transport into the liver, the main site of statin metabolism and elimination
SLCO1B1 polymorphism is thought to have a lesser effect on the more hydrophilic statins (eg, rosuvastatin, fluvastatin) compared with those that are more lipophilic (eg, atorvastatin, simvastatin)
Other genetic polymorphisms of elimination (eg, CYP450, P-glycoprotein) for each individual drug must also be considered, to explain variability for statin clearance among patients that exhibit SCLO1B1 polymorphism
SLCO1B1 CC genotype is most common in Caucasians and Asians (15%)
Risk of myopathy is 2.6- to 4.3-fold higher if the C allele is present and 16.9-fold higher in CC homozygotes than in TT homozygotes
Genetic testing laboratories

  • Optivia Biotechnology, Inc (http://optiviabio.com)