ABSTRACT
Title
Effects of itraconazole on the pharmacokinetics of ciprofloxacin and the intestinal metabolizing system (CYP450 and P-glycoprotein)
Authors
A. Benini, T. Della Bora, E. Bertazzoni Minelli
Dept. Public Health and Community Medicine, Pharmacology Section, University of Verona, Verona, Italy
Dept. Public Health and Community Medicine, Pharmacology Section, University of Verona, Verona, Italy
Abstract
Itraconazole (Itz), an antifungal azole and a strong inhibitor of the liver metabolism, can modify the pharmacokinetic parameters of various drugs. Ciprofloxacin (Cpx), a fluoroquinolone widely utilized in clinical practice, exhibits a transintestinal elimination. An effect of Itz on Cpx pharmacokinetics is possible. Objective of this research is to study the in vivo drug interactions between Cpx and Itz at gastrointestinal level in rat. We studied the distribution of Cpx in gastrointestinal tract and the expression of pharmaco-metabolizing system CYP450 and Pgp (intestine and liver).
16 Wistar outbred female rats (210±10 g, mean ± SD) were subdivided in 4 groups and treated orally by gavage for three days as follows: 1- Cpx (30 mg/kg/day); 2- Itz (10 mg/kg/day); 3- Itz (10 mg/kg/day, two hours before Cpx) and Cpx (30 mg/kg/day); 4- control group (no drug treatment).Serum, small intestine, liver and faeces were collected two hours after the last drug administration. Cpx concentrations were determined in all samples by microbiological method (agar–well diffusion method, K. pneumoniae, 0.02% final concentration as test microorganism).In parallel, changes in the expression of CYP450 3A4 and P-gp were determined in small intestine and liver by Western-blotting.
Pharmacokinetics: the pretreatment with Itz caused a significant increase of Cpx concentrations in both serum (0,3 + 0,1 mg/l, mean ± SD) and liver (0.8 ± 0.4 mg/kg) in comparison to Cpx alone (0,13 ± 0,07 mg/l in serum and 0.3 ± 0.2 mg/kg in liver). Concentrations of Cpx alone in intestinal tissue (11,5 ± 7.4 mg/kg) slightly increased in presence of Itz (14.7 ± 8.5 mg/kg). Fecal concentrations of Cpx alone were 85.1 + 26.1 mg/kg and increased after treatment with the combination Cpx + Itz (125.3 ± 11.56 mg/kg).
Enzymes - liver: the hepatic expression of CYP450 3A4 slightly increased after treatment with Cpx alone (+6.7%, compared with untreated controls); Itz alone caused a modest reduction
(-2.8%); this reduction was more marked after treatment with the Itz + Cpx combination (-5.2%). No modifications were determined by Cpx alone on the hepatic expression of Pgp; Pgp expression was reduced by treatment with Itz alone (-8%), being the value similar to that determined by the combination (-9.3%).
Intestine: Cpx and Itz alone did not modify the intestinal expression of CYP450 3A4
(-2.2% and -0.1%, respectively), while their combination caused a decrease (-14.3%). Cpx alone, Itz alone and Cpx + Itz determined an increase in the intestinal Pgp expression corresponding to 64.4%, 42.2% and 84.3%, respectively, when compared to control.
Itz alone shows inhibitory effects on the expression of CYP450 3A4 and Pgp in the liver, and these effects became more marked with the administration of Cpx. The behaviour in intestinal tissue is quite different, because Itz exerted the inhibitory effect against the CYP450 3A4 both alone and in combination with Cpx, while induced an increase in the intestinal expression of Pgp. These preliminary results confirm data from literature (i.e. drug serum increase, hepatic metabolism inhibition) and add new data on the transintestinal elimination of Cpx. The relationship between Cpx pharmacokinetics and the intestinal pharmaco-metabolizing system need further evaluations.
16 Wistar outbred female rats (210±10 g, mean ± SD) were subdivided in 4 groups and treated orally by gavage for three days as follows: 1- Cpx (30 mg/kg/day); 2- Itz (10 mg/kg/day); 3- Itz (10 mg/kg/day, two hours before Cpx) and Cpx (30 mg/kg/day); 4- control group (no drug treatment).Serum, small intestine, liver and faeces were collected two hours after the last drug administration. Cpx concentrations were determined in all samples by microbiological method (agar–well diffusion method, K. pneumoniae, 0.02% final concentration as test microorganism).In parallel, changes in the expression of CYP450 3A4 and P-gp were determined in small intestine and liver by Western-blotting.
Pharmacokinetics: the pretreatment with Itz caused a significant increase of Cpx concentrations in both serum (0,3 + 0,1 mg/l, mean ± SD) and liver (0.8 ± 0.4 mg/kg) in comparison to Cpx alone (0,13 ± 0,07 mg/l in serum and 0.3 ± 0.2 mg/kg in liver). Concentrations of Cpx alone in intestinal tissue (11,5 ± 7.4 mg/kg) slightly increased in presence of Itz (14.7 ± 8.5 mg/kg). Fecal concentrations of Cpx alone were 85.1 + 26.1 mg/kg and increased after treatment with the combination Cpx + Itz (125.3 ± 11.56 mg/kg).
Enzymes - liver: the hepatic expression of CYP450 3A4 slightly increased after treatment with Cpx alone (+6.7%, compared with untreated controls); Itz alone caused a modest reduction
(-2.8%); this reduction was more marked after treatment with the Itz + Cpx combination (-5.2%). No modifications were determined by Cpx alone on the hepatic expression of Pgp; Pgp expression was reduced by treatment with Itz alone (-8%), being the value similar to that determined by the combination (-9.3%).
Intestine: Cpx and Itz alone did not modify the intestinal expression of CYP450 3A4
(-2.2% and -0.1%, respectively), while their combination caused a decrease (-14.3%). Cpx alone, Itz alone and Cpx + Itz determined an increase in the intestinal Pgp expression corresponding to 64.4%, 42.2% and 84.3%, respectively, when compared to control.
Itz alone shows inhibitory effects on the expression of CYP450 3A4 and Pgp in the liver, and these effects became more marked with the administration of Cpx. The behaviour in intestinal tissue is quite different, because Itz exerted the inhibitory effect against the CYP450 3A4 both alone and in combination with Cpx, while induced an increase in the intestinal expression of Pgp. These preliminary results confirm data from literature (i.e. drug serum increase, hepatic metabolism inhibition) and add new data on the transintestinal elimination of Cpx. The relationship between Cpx pharmacokinetics and the intestinal pharmaco-metabolizing system need further evaluations.