Niacin/lovastatin drug interactions

# Drug Interactions

## Niacin
Antihypertensive Therapy - Niacin may potentiate the effects of ganglionic blocking agents and vasoactive drugs resulting in postural hypotension.
Aspirin - Concomitant aspirin may decrease the metabolic clearance of Niacin. The clinical relevance of this finding is unclear.
Bile Acid Sequestrants - An in vitro study was carried out investigating the Niacin-binding capacity of colestipol and cholestyramine. About 98% of available Niacin was bound to colestipol, with 10 to 30% binding to cholestyramine. These results suggest that 4 to 6 hours, or as great an interval as possible, should elapse between the ingestion of bile acid-binding resins and the administration of ADVICOR.
Other - Concomitant alcohol or hot drinks may increase the side effects of flushing and pruritus and should be avoided around the time of ADVICOR ingestion. Vitamins or other nutritional supplements containing large doses of Niacin or related compounds such as nicotinamide may potentiate the adverse effects of ADVICOR.

## Lovastatin
Lovastatin is metabolized by CYP3A4 but has no CYP3A4 inhibitory activity; therefore it is not expected to affect the plasma concentrations of other drugs metabolized by CYP3A4. Strong inhibitors of CYP3A4 (e.g., itraconazole, ketoconazole, posaconazole, clarithromycin, telithromycin, HIV protease inhibitors, boceprevir, telaprevir, nefazodone, and erythromycin), and large quantities of grapefruit juice (>1 quart daily) increase the risk of ] by reducing the elimination of lovastatin (seeWARNINGS, ]/]).
In vitro studies have demonstrated that voriconazole inhibits the metabolism of lovastatin. Adjustment of the lovastatindose may be needed to reduce the risk of myopathy, including rhabdomyolysis, if voriconazole must be used concomitantly with lovastatin.
Interactions With Lipid-Lowering Drugs That Can Cause myopathy When Given Alone
The risk of myopathy is also increased by the following lipid-lowering drugs that are not strong CYP3A4 inhibitors, but which can cause myopathy when given alone (seeWARNINGS, myopathy/rhabdomyolysis).

## Gemfibrozil
Other fibrates

### Other Drug Interactions
Cyclosporine: The risk of myopathy/rhabdomyolysis is increased by concomitant administration of cyclosporine (see WARNINGS, myopathy/rhabdomyolysis).
Danazol, Diltiazem, or Verapamil: The risk of myopathy/rhabdomyolysis is increased by concomitant administration of danazol, diltiazem, or verapamil particularly with higher doses of lovastatin(see WARNINGS, myopathy/rhabdomyolysis and CLINICAL PHARMACOLOGY, Pharmacokinetics).
Amiodarone: The risk of myopathy/rhabdomyolysis is increased when amiodarone is used concomitantly with a closely related member of the HMGCoA reductase inhibitor class (see WARNINGS, myopathy/rhabdomyolysis).
Coumarin Anticoagulants - In a small clinical study in which lovastatinwas administered to warfarin-treated patients, no effect on PT was detected. However, another HMG-CoA reductase inhibitor has been found to produce a less than two seconds increase in PT in healthy volunteers receiving low doses of warfarin. Also, bleeding and/or increased PT have been reported in a few patients taking coumarin anticoagulants concomitantly with lovastatin. It is recommended that in patients taking anticoagulants, PT be determined before starting ADVICOR and frequently enough during early therapy to insure that no significant alteration of PT occurs. Once a stable PT has been documented, PT can be monitored at the intervals usually recommended for patients on coumarin anticoagulants. If the dose of ADVICOR is changed, the same procedure should be repeated.
Colchicine - Cases of myopathy, including rhabdomyolysis, have been reported with lovastatincoadministered with colchicine.
Ranolazine - The risk of myopathy, including rhabdomyolysis, may be increased by concomitant administration of ranolazine.
Propranolol - In normal volunteers, there was no clinically significant pharmacokinetic or pharmacodynamic interaction with concomitant administration of single doses of lovastatinand propranolol.
Digoxin - In patients with hypercholesterolemia, concomitant administration of lovastatinand digoxin resulted in no effect on digoxin plasma concentrations.
Oral Hypoglycemic Agents - In pharmacokinetic studies of lovastatinin hypercholesterolemic, non-insulin dependent diabetic patients, there was no drug interaction with glipizide or with chlorpropamide.

## Drug/Laboratory Test Interactions
Niacin may produce false elevations in some fluorometric determinations of plasma or urinary catecholamines. Niacin may also give false-positive reactions with cupric sulfate solution (Benedict's reagent) in urine glucose tests.