The mode of action of statins is HMG-CoA reductase enzyme inhibition. This enzyme is needed by the body to make cholesterol.
Lovastatin causes cholesterol to be lost from LDL, but also reduces the concentration of circulating LDL (low density lipoprotein) particles. Apolipoprotein B concentration falls substantially during treatment with lovastatin. Lovastatin's ability to lower LDL is thought to be due to a reduction in VLDL, which is a precursor to LDL. Also, Lovastatin may increase the number of LDL receptors on the surface of cell membranes, and thus increase the breakdown of LDL.
Lovastatin can also produce slight to moderate increases in HDL, and slight to moderate decreases in triglycerides. Both of these effects are typically beneficial to a patient with a poor lipid profile.
Both lovastatin and its b-hydroxyacid metabolite are highly bound (>95%) to human plasma proteins. Animal studies demonstrated that lovastatin crosses the blood-brain and placental barriers. Elderly patients, or those with renal insufficiency may have higher plasma concentrations of lovastatin after administration and may require a lower dose. The usual recommended starting dose is 20 mg once a day given with the evening meal, and the dose range is 10-80 mg a day in a single dose, or divided into two doses.
Lovastatin is usually well tolerated. Lovastatin, and all statin drugs, can rarely cause myopathy or rhabdomyolysis. This can be life-threatening if not recognised and treated in time, and so any unexplained muscle pain or weakness whilst on lovastatin should be promptly mentioned to the prescribing doctor.
As with all the statin drugs, drinking grapefruit juice during therapy increases the risk of serious side effects. Grapefruit juice inhibits CYP3A4, and thus decreases the metabolism of statins, increasing their plasma concentrations.
Lovastatin at doses higher than 20 mg per day should not be used in conjunction with gemfibrozil or other fibrates, niacin, or cyclosporin. This is because of the significantly increased risk of rhabdomyolysis.
Lovastatin tablets are preserved in well closed, light resistant containers. Protected from light and stored either in a cool place or at controlled room temperature.
Lovastatin tablets are tested for Dissolution and Assay as per the USP.
Limit for Dissolution – Not less than 80% (Q) of the labeled amount of Lovastatin is dissolved in 30 mins.
Limit for Assay – Each tablet contains not less than 90% and not more than 110% of the labeled amount of Lovastatin, tested by HPLC analysis.
Lovastatin raw material contains 5 impurities – A, B, C, D and E (as shown below).