Analysis of the pharmacokinetic interaction between cephalexin and quinapril by a nonlinear mixed-effect model

Irinotecan-induced gastrointestinal damage alters the expression of peptide transporter 1 and absorption of cephalexin in rats

Irinotecan causes severe gastrointestinal damage, which may affect the expression of intestinal transporters. However, neither the expression of peptide transporter 1 (Pept1) nor the pharmacokinetics of Pept1 substrate drugs has been investigated under irinotecan-induced gastrointestinal damage. Therefore, the present study quantitatively investigated the effects of irinotecan-induced gastrointestinal damage on the intestinal expression of Pept1 and absorption of cephalexin (CEX), a typical Pept1 substrate, in rats. Irinotecan was administered intravenously to rats for 4 days to induce gastrointestinal damage. The expression of Pept1 mRNA and the Pept1 protein in the upper, middle, and lower segments of the small intestine of irinotecan-treated rats was assessed by quantitative real-time polymerase chain reaction (PCR) and western blotting, respectively. The pharmacokinetic profile of CEX was examined after its oral or intravenous administration (10 mg/kg). In irinotecan-treated rats, ∼2-fold increases in Pept1 protein levels were observed in all three segments, whereas mRNA levels remained unchanged. The oral bioavailability of CEX significantly decreased to 76% of that in control rats. The decrease in passive diffusion caused by intestinal damage may have overcome the increase in Pept1-mediated uptake. In conclusion, irinotecan may decrease the intestinal absorption of Pept1 substrate drugs; however, it increased the expression of intestinal Pept1.

Changes of drug pharmacokinetics mediated by downregulation of kidney organic cation transporters Mate1 and Oct2 in a rat model of hyperuricemia

The effects of hyperuricemia on the expression of kidney drug transporters and on the pharmacokinetics of several substrate drugs were examined. We first established a rat model of hyperuricemia without marked symptoms of chronic kidney failure by 10-day co-administration of oxonic acid (uricase inhibitor) and adenine (biosynthetic precursor of uric acid). These hyperuricemic rats showed plasma uric acid concentrations of up to 6 mg/dL, which is similar to the serum uric acid level in hyperuricemic humans, with little change of inulin clearance. The mRNA levels of multidrug and toxin extrusion 1 (Mate1, Slc47a1), organic anion transporter 1 (Oat1, Slc22a6), organic cation transporter 2 (Oct2, Slc22a2), urate transporter 1 (Urat1, Slc22a12) and peptide transporter 1 (Pept1, Slc15a1) were significantly decreased in kidney of hyperuricemic rats. Since Oct2, Mate1 and Oat1 are important for renal drug elimination, we next investigated whether the pharmacokinetics of their substrates, metformin, cephalexin and creatinine, were altered. The plasma concentration of metformin was not affected, while its kidney tissue accumulation was significantly increased. The plasma concentration and kidney tissue accumulation of cephalexin and the plasma concentration of creatinine were also increased. Furthermore, the protein expression of kidney Mate1 was decreased in hyperuricemic rats. Accordingly, although multiple factors may influence renal handling of these drugs, these observations can be accounted for, at least in part, by downregulation of Mate1-mediated apical efflux from tubular cells and Oct2-mediated basolateral uptake. Our results suggest that hyperuricemia could alter the disposition of drugs that are substrates of Mate1 and/or Oct2.

The effect of cephalexin in influencing the pharmacokinetics of a novel drug - 5'-valyl-cytarabine hydrochloride

The aim of this study is to investigate the pharmacokinetics of 5′-valyl-cytarabine hydrochloride (OPC) when co-administered with cephalexin, which are both the substrates of PepT1. The drugs were administered orally by gavage. Blood samples were collected from the orbital plexus of the rats after oral administration of drug solutions. A new high-performance liquid chromatographic method was validated and used for determination of the two drugs. Pharmacokinetic parameters were calculated using DAS 2.1.1 software with noncompartmental analysis. After oral administration of OPC and co-administration of OPC and cephalexin, there were significant differences in the main pharmacokinetic parameters. The main pharmacokinetic parameters for the OPC group and the co-administrative group were as follows: AUC_0-10 (18,168.7 ± 2561.4) ng⋅h/ml and (13,448.5 ± 2544.73) ng⋅h/ml, AUC_0-∞ (18,683.1 ± 3066.5) ng⋅h/ml and (13,721.1 ± 2683.0) ng⋅h/ml, C_max (6654.8 ± 481.3) ng/ml and (4765.1 ± 928.9) ng/ml, respectively. The results showed that the bioavailability of OPC could be reduced when co-administered with cephalexin, suggesting that the efficacy of a novel drug might be reduced when it came to combination use of β-lactam antibiotics.

Few Drugs Display Flip-Flop Pharmacokinetics and These Are Primarily Associated with Classes 3 and 4 of the BDDCS

This study was conducted to determine the number of drugs exhibiting flip-flop pharmacokinetics following oral (p.o.) dosing from immediate-release dosage forms and if they exhibit a common characteristic that may be predicted based on BDDCS classification. The literature was searched for drugs displaying flip-flop kinetics (i.e., absorption half-life larger than elimination half-life) in mammals in PubMed, via internet search engines and reviewing drug pharmacokinetic data. Twenty two drugs were identified as displaying flip-flop kinetics in humans (13 drugs), rat (nine drugs), monkey (three drugs), horse (two drugs), and/or rabbit (two drugs). Nineteen of the 22 drugs exhibiting flip-flop kinetics were BDDCS Classes 3 and 4. One of the three exceptions, meclofenamic acid (Class 2), was identified in the horse; however, it would not exhibit flip-flop kinetics in humans where the p.o. dosing terminal half-life is 1.4 h. The second, carvedilol, can be explained based on solubility issues, but the third sapropterin dihydrochloride (nominally Class 1) requires further consideration. The few drugs displaying p.o. flip-flop kinetics in humans are predominantly BDDCS Classes 3 and 4. New molecular entities predicted to be BDDCS Classes 3 and 4 could be liable to exhibit flip-flop kinetics when the elimination half life is short and should be suspected to be substrates for intestinal transporters.

Three-ways crossover bioequivalence study of cephalexin in healthy Malay volunteers

CONTEXT

Although the general pharmacokinetics of cephalexin is quite established up-to-date, however, no population-based study on Cephalexin pharmacokinetics profile in Malay population has been reported yet in the literature.

OBJECTIVE

The objective of this study was to investigate the pharmacokinetics and to compare the bioavailability of three cephalexin products, Ospexin® versus MPI Cephalexin® tablet and MPI Cephalexin® capsule, in healthy Malay ethnic male volunteers in Malaysia.

MATERIAL AND METHOD

A single dose, randomized, fasting, three-period, three-treatment, three-sequence crossover, open label bioequivalence study was conducted in 24 healthy Malay adult male volunteers, with 1 week washout period. The drug concentration in the sample was analyzed using high performance liquid chromatography.

RESULT

The mean (SD) pharmacokinetic parameter results of Ospexin® were Cmax, 17.39 (4.15) μg/mL; AUC0-6, 28.90 (5.70) µg/mL * h; AUC0-∞, 30.07 (5.94) µg/mL * h; while, those of MPI Cephalexin® tablet were Cmax, 18.29 (3.01) μg/mL; AUC0-6, 30.02 (4.80) µg/mL * h; AUC00-∞, 31.33 (5.18) µg/mL * h and MPI Cephalexin® capsule were Cmax, 18.25 (3.92) μg/mL; AUC0-6, 30.04 (5.13) µg/mL * h; AUC0-∞, 31.22 (5.29) µg/mL * h.

CONCLUSION

The 90% confidence intervals for the logarithmic transformed Cmax, AUC0-6 and AUC0-∞, of Ospexin® versus MPI Cephalexin® tablet and Ospexin® versus MPI Cephalexin® capsule were between 0.80 and 1.25. Both Cmax and AUC met the predetermined criteria for assuming bioequivalence. The pharmacokinetic profile of cephalexin in Malay population does not vary much from other world population.

Dermal drug levels of antibiotic (cephalexin) determined by electroporation and transcutaneous sampling (ETS) technique

The purpose of this project was to assess the validity of a novel Electroporation and transcutaneous sampling (ETS) technique for sampling cephalexin from the dermal extracellular fluid (ECF). This work also investigated the plausibility of using cephalexin levels in the dermal ECF as a surrogate for the drug levels in the synovial fluid. In vitro and in vivo studies were carried out using hairless rats to assess the workability of ETS. Cephalexin (20 mg/kg) was administered (i.v.) through tail vein and the time course of drug concentration in the plasma was determined. In the same rats, cephalexin concentration in the dermal ECF was determined by ETS and microdialysis techniques. In a separate set of rats, only intraarticular microdialysis was carried out to determine the time course of cephalexin concentration in synovial fluid. The drug concentration in the dermal ECF determined by ETS and microdialysis did not differ significantly from each other and so as were the pharmacokinetic parameters. The results provide validity to the ETS technique. Further, there was a good correlation ( approximately 0.9) between synovial fluid and dermal ECF levels of cephalexin indicating that dermal ECF levels could be used as a potential surrogate for cephalexin concentration in the synovial fluid.

Interethnic differences of PEPT2 (SLC15A2) polymorphism distribution and associations with cephalexin pharmacokinetics in healthy Asian subjects

OBJECTIVES

The aims of this study were to characterize the population frequency of PEPT2 (SLC15A2) polymorphic variants in three Asian ethnic populations, namely Chinese, Malay and Asian Indian, and to investigate the associations of ethnicity (Chinese vs. Asian Indian), PEPT2 haplotype and cephalexin pharmacokinetics in healthy Asian subjects.

METHODS

PEPT2 polymorphisms were screened from a cohort of 96 Chinese, 96 Malay and 96 Asian Indian subjects. Cephalexin (1000 mg, orally) pharmacokinetics was characterized in an additional 15 Chinese and 15 Asian Indian healthy subjects. These 30 subjects were subsequently genotyped for their PEPT2 polymorphisms.

RESULTS

In total, ten common single nucleotide polymorphisms (SNPs) were detected in the three populations, forming two PEPT2 haplotypes. There were significant ethnic differences in PEPT2 haplotype distribution: the frequencies of the *1 and *2 alleles were 0.307 and 0.693 in the Chinese population, 0.495 and 0.505 in the Malay population and 0.729 and 0.271 in Asian Indian population, respectively. The C (max) of cephalexin was significantly lower in the Chinese (29.80 +/- 4.09 microg ml(-1)) population than in the Asian Indian one (33.29 +/- 4.97 microg ml(-1); P = 0.045). This difference could be explained by the higher average body weight of the Chinese population. There was no other significant difference in cephalexin pharmacokinetics between either ethnic or PEPT2 genotype groups.

CONCLUSION

PEPT2 polymorphism distributions differ significantly between Chinese, Malay and Asian Indian populations. However, cephalexin pharmacokinetics is not meaningfully different between Chinese and Asian Indians. The association between the PEPT2 haplotype and cephalexin pharmacokinetics could not be confirmed, and future studies under better controlled conditions are needed.

Excretion and ecotoxicity of pharmaceutical and personal care products in the environment

The presence and fate of pharmaceutical and personal care products (PPCPs) in the environment is undergoing increasing scrutiny. The existing clinical pharmacokinetics and pharmacodynamics data for 81 common compounds were examined for cues of ecotoxicity. Of these the proportions excreted were available for 60 compounds (i.e., 74%). The compounds had a low (< or =0.5%), a moderately low (6-39%), a relatively high (40-69%), or a high (> or =70%) proportion of the parent compound excreted. More than half of the compounds evaluated have low or moderately low proportions of the parent compound excreted. However, the proportions excreted were negatively but moderately correlated (r = -0.50; n = 13; P = 0.08) with the concentrations of the compounds in the aquatic environment, suggesting that the compounds that have low proportions excreted may also have inherently low degradability in the environment. Solubility, logK(ow), and pKa work well in predicting the behavior of PPCPs under clinical conditions and have been used in the environmental assessment of PPCPs prior to approval. However, these parameters did not correlate with the proportion of PPCPs excreted in the environment or their concentration in the environment, underscoring the need for research into the behavior of PPCPs in the environment. PPCPs occur in low concentrations in the environment and are unlikely to elicit acute toxicity. An ecotoxicity potential that is based on chronic toxicity, bioavailability, and duration of exposure to nontarget organisms is described as a guide in assessing the potency of these compounds in the environment.

Alterations in cefalosporin levels in the serum and mandible of hyperlipaedemic rats after co-administration of ibuprofen

Several interactions between antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) have been described in the literature, and it has been reported that hyperlipidaemia induces significant changes in cefalosporin levels. The aim of this study was to determine the changes in the levels of several cefalosporins in the serum and mandible after ibuprofen co-administration in hyperlipaedemic rats. One hundred and forty male Wistar rats were used and divided in 4 groups (A-D), each of which was further divided into 5 subgroups (1-5), either with placebo or with various treatment regimes. The co-administration of NSAIDs led to increased cefalosporin levels in both control and hyperlipidaemic animals. Hyperlipidaemia was also found to augment cefalosporin levels. These observed increases might be due to the displacement of the cephalosporins from their binding sites in serum albumin and tissue proteins in the presence of ibuprofen. NSAIDs showed a greater binding affinity for tissue proteins compared to the cephalosporins, and probably play an antagonistic role in protein binding, resulting in higher concentrations of antibiotics.

Pharmacokinetic models for the saturable absorption of cefuroxime axetil and saturable elimination of cefuroxime

Since oligopeptidic drugs such as beta-lactam antibiotics share the same carriers in humans and animals, the absorption and elimination kinetics of cefuroxime (C) were investigated in rats. Plasma C concentrations were measured by liquid chromatography. Pharmacokinetics and bioavailability of C in the rat were examined after intravenous (i.v.) administration at three doses (1.78, 8.9 and 17.8mg) of cefuroxime sodium and oral administration at two doses (2.02 and 8.9mg) of cefuroxime axetil (CA). Preliminary fits using data from intravenous administration of C showed that the drug disposition kinetics were clearly nonlinear, with an increase in plasma clearance as the intravenous dose increased. After oral administration of CA, normalized C(max) was higher for smaller dose than for the largest dose. The population pharmacokinetic parameters were obtained by means of nonlinear mixed effect modelling approach according to a nonlinear elimination and nonlinear absorption two-compartment model. The nonlinear elimination could be attributed to a saturable renal tubular reabsorption of the antibiotic and nonlinear intestinal absorption of CA mediated by carrier system. The oral bioavailability of C, calculated by numeric integration of an amount of CA drug absorbed was 22 and 17% for 2.02 and 8.9mg of prodrug administered orally.

Intestinal absorption of cephalexin in diabetes mellitus model rats

We investigated the intestinal absorption and pharmacokinetics of cephalexin, as well as the intestinal H+/oligopeptide transporter PEPT1 mRNA and protein levels in type 1 and type 2 diabetic rats. Cephalexin disappearance from the duodenum loop was significantly lower in streptozotocin-induced type 1 diabetic rats and higher in hyperinsulinemic type 2 diabetic GK and Zucker-fa/fa (Zucker) rats, than in control rats. These results were speculated to be due to the enhancement of intestinal absorption of cephalexin in GK and Zucker rats. Intestinal PEPT1 mRNA levels were not significantly different between control and diabetic rats; however, the brush-border membrane vesicle PEPT1 protein levels were increased in GK and Zucker rats. After oral administration of cephalexin, plasma cephalexin concentrations and pharmacokinetic parameters, area under the concentration versus time curve from 0 to infinity, AUC(0-->infinity), and maximum plasma concentration, Cmax, in GK and Zucker rats were markedly higher than in control rats. From these findings, it is considered that intestinal absorption of drugs mediated by PEPT1 may be enhanced in hyperinsulinemic type 2 diabetes mellitus rats.