Flomax Clinical Pharmacology

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Flomax - Clinical Pharmacology [Tamsulosin]

Absorption:

Absorption of tamsulosin HCI from FLOMAX capsules 0.4 mg is essentially complete (> 90%) following oral administration under fasting conditions. Tamsulosin HCI exhibits linear kinetics following single and multiple dosing, with achievement of steady-state concentrations by the fifth day of once-a-day dosing.

Effect of Food:

The time to maximum concentration (Tmax) is reached by four to five hours under fasting conditions and by six to seven hours when FLOMAX capsules are administered with food. Taking FLOMAX capsules under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak concentrations (Cmax) compared to fed conditions
(Figure 1).
Figure 1: Mean Plasma Tamsulosin HCI Concentrations Following Single-Dose Administration of FLOMAX capsules 0.4 mg Under Fasted and Fed

Conditions (n= 8)

The effects of food on the pharmacokinetics of tamsulosin HCI are consistent regardless of whether a FLOMAX capsule is taken with a light breakfast or a high-fat breakfast (Table 1).
TABLE 1 Mean (ą S. D.) Pharmacokinetic Parameters Following FLOMAX capsules 0.4 mg Once Daily or 0.8 mg Once Daily with a Light Breakfast, High-Fat
Breakfast or Fasted Pharmacokinetic
Parameter 0. 4 mg q. d. to healthy volunteers; n= 33 (age range 18-32 years) 0.8 mg q. d. to healthy volunteers; n= 22 (age range 55-75 years) Light Breakfast Fasted Light Breakfast High-Fat Breakfast Fasted
Cmin (ng/ mL) 4.0 ą 2.6 3.8 ą 2.5 12.3 ą 6.7 13.5 ą 7.6 13.3 ą 13. 3 Cmax (ng/ mL)
10.1 ą 4.8 17.1 ą 17. 1 29.8 ą 10. 3 29.1 ą 11. 0 41.6 ą 15. 6 Cmax/ Cmin Ratio 3.1 ą 1.0 5.3 ą 2.2 2.7 ą 0.7 2.5 ą 0.8 3.6 ą 1.1

Tmax (hours) 6.0 4.0 7.0 6.6 5.0 T1/ 2 (hours) ----14.9 ą 3.9
AUC . (ng . hr/ mL) 151 ą 81. 5 199 ą 94. 1 440 ą 195 449 ą 217 557 ą 257 Cmin = observed minimum concentration
Cmax = observed maximum tamsulosin HCI plasma concentration Tmax = median time-to-maximum concentration
T1/ 2 = observed half-life AUC . = Area under the tamsulosin HCI plasma time curve over the dosing interval