Drug Interactions between Slo-Niacin and tamsulosin

ADJUST DOSING INTERVAL: Food may delay the gastrointestinal absorption of tamsulosin. The time to maximum plasma concentration (Tmax) is reached by 4 to 5 hours under fasted conditions and by 6 to 7 hours when tamsulosin is administered with food. The delay in Tmax has the desirable effect of smoothing the tamsulosin plasma concentration profile, thereby reducing fluctuation of the plasma peak and trough concentrations with multiple dosing. Food may also affect the extent of absorption of tamsulosin. It has been reported that taking tamsulosin under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak plasma concentration (Cmax) compared to fed conditions. The effects of food on the pharmacokinetics of tamsulosin are consistent regardless of whether tamsulosin is taken with a light meal or a high-fat meal.

MANAGEMENT: To ensure uniformity of absorption, tamsulosin should be administered approximately one-half hour following the same meal each day.

GENERALLY AVOID: Ethanol can exacerbate the cutaneous flushing that is a common side effect of niacin. At least one case of delirium and lactic acidosis has been reported with coadministration of these drugs, although data are limited.

MANAGEMENT: Coadministration should probably be discouraged, particularly since chronic consumption of large amounts of alcohol is associated with hyperlipidemia.

A single case has been reported in which cutaneous flushing and tremors were noted in a woman who was taking niacin while wearing a nicotine patch. The mechanism is suspected to be synergistic cutaneous vasodilatory effects. The clinical significance of this possible interaction is not known.