Drug Interaction Report

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.

ADJUST DOSING INTERVAL: Food may reduce the oral absorption and bioavailability of trospium chloride. According to the product labeling, administration of trospium chloride with a high fat meal reduced the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by 70% to 80% compared to administration while fasting.

MANAGEMENT: To ensure maximal oral absorption, trospium chloride should be administered at least 1 hour before meals or on an empty stomach. If trospium chloride is administered as a combination with xanomeline, the manufacturer recommends administering the capsules at least 1 hour before a meal or at least 2 hours after a meal. Capsules should be taken whole.