China Pharmaceutical University The determination of ic parameters and relative bioavailability in vivo of Ciprofloxacin capsules Purposes Principles Procedures Questions Results 何伟 Tel:********** ******@cpu. Purposes To master the evaluation method of relative bioavailability of ciprofloxacin from urine excretion data.
To be familiar with the determination of ic parameters by urinary excretion rate and sigma-minus method CPU Principles Bioavaliability, F The measurement of the drug rate and extent which is systemically available. Expressed by Relative and absolute bioavaliability. Evaluation method of F Plasma concentration method Urinary excretion method Urinary excretion method Only if urinary excretion of unchanged drug is the main mechanism of the drug and the total amount of drug in urine is correlated to the total amount of drug absorbed; Urine samples should be clollected as long as possible (≧7 t1/2) CPU Urinary excretion method——urinary excretion rates method Drug are eliminated by a first-order rate process
(1)
When e-kat→0, △Xu/△t replace dXu/dt, tc replace t, (1)can be rewritten as following:
(3) Ln△Xu/△t -tc: elimination rate constant k=-斜率值 half-life t1/2 = (2) 瞬时尿药速率很难求得,只能在某段间隔时间内收集尿液,并得到该段时间的原形药物量,实际中应用的是平均速率与时间的关系求动力学参数。 CPU CPU Urinary excretion method——sigma-minus method Equation (1) is integrated as shown below:
(3) When t →∞ equation (3) reduces to (4) When equation (4) subtract equation (3):
(5) Therefore k= -斜率值 ka is obtained from the intercept of this curve Xu∞=Xu+ (△Xu/△t) t/k CPU Procedures Equipments and materials
Methods of drug administration The healthy volunteers that take no any medications before drug administration are selected. After emptying urine in the morning,a single 250 mg dose of ciprofloxacin capsules (250mg) is taken with 200 ml of water. Urine should be collected on time after administration, and put down the volumes accurately. Standar
