Oral Administration Of Rifampicin Research Articles

An improved TK-NOG mouse as a novel platform for humanized liver that overcomes limitations in both male and female animals

We developed a novel immunodeficient NOG mouse expressing HSVtk mutant clone 30 cDNA under the control of mouse transthyretin gene enhancer/promoter (NOG-TKm30) to acquire fertility in males and high inducibility of liver injury in females. Maximum human albumin levels (approx. 15 mg/mL plasma) in both male and female NOG-TKm30 mice engrafted with human hepatocytes (humanized liver mice) were observed 8–12 weeks after transplantation. Immunohistochemical analyses revealed abundant expression of major human cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2D6, CYP2E1, and CYP3A4) in reconstituted liver with original zonal distribution. In vivo drug–drug interactions were observed in humanized liver mice as decreased area under the curve of midazolam (CYP3A4/5 substrate) and omeprazole (CYP3A4/5 and CYP2C19 substrate) after oral administration of rifampicin. Furthermore, we developed a pregnant model for evaluating prenatal exposure to drugs. The detection of thalidomide metabolites in the fetuses of pregnant humanized liver mice indicates that the novel TK model can be used for developmental toxicity studies requiring the assessment of human drug metabolism. These results suggest that the limitations of traditional TK-NOG mice can be addressed using NOG-TKm30 mice, which constitute a novel platform for humanized liver for both in vivo and in vitro studies.

Rifampicin activates AMPK and alleviates oxidative stress in the liver as mediated with Nrf2 signaling

Although rifampicin could have a hepatic toxic effect, it has also been shown that this chemical acts as a cellular protectant against oxidative stress. Therefore, we wondered whether rifampicin has a beneficial effect such as an anti-oxidant in the liver, because the efficacy of some drugs sometimes relates with their toxicity as well as protective effects. The present study aimed to investigate the antioxidant effect of rifampicin against arachidonic acid (AA) plus iron (AA + iron) cotreatment and against acetaminophen (APAP, 500 mg/kg)-induced oxidative stress, in vitro and in vivo, respectively. In vivo, oral administration of rifampicin (100 or 200 mg/kg) attenuated elevation of serum alanine aminotransferase (ALT) and aspartate transaminase (AST), serum liver injury markers, against APAP treatment and, histologically, ameliorated tissue damage. Under in vitro examination, MTT assays were used to assess the cell death inhibitory effect of rifampicin against AA + iron-induced oxidative stress. In addition, DCFH-DA and Rh 123 staining showed that rifampicin treatment reduced reactive oxygen species (ROS) production and mitochondrial membrane damage, which had been induced by AA + iron treatment. Further, we explored whether rifampicin treatment enhanced phosphorylation of AMP-activated protein kinase (AMPK) by activation of liver kinase B1 (LKB1), the upstream kinase of AMPKα. Activated AMPKα induced activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), which are proteins functioning in redox balance. Moreover, we confirmed a reversed cell protective effect of rifampicin under compound C (an AMPK inhibitor) treatment. Overall, our data demonstrate that rifampicin effectively protects the liver against cellular oxidative stress through AMPKα and Nrf2 pathway.

Measurement of rifampicin concentrations in tuberculous pleural effusion before and after combination treatment with oral and local rifampicin

Objective: To investigate the changes of rifampin concentrations in pleural effusion before and after combination treatment with oral and pleural administration of rifampicin by electro-phonophoresis(EP). Methods: A self-control study was performed in 32 cases of tuberculous pleurisy treated in the Second Department of Respiratory Medicine of Affiliated Hospital of Zunyi Medical College between September 2016 and January 2018. Based on the weight of each patient, an oral administration of isoniazid (0.3-0.4 g/d), rifampicin (0.45-0.60 g/d),ethambutol(0.75 g/d),and pyrazinamide (1.0-1.5 g/d) were given. After a 5-day traditional anti-tuberculosis treatment, an additional EP treatment was applied by penetrating chest wall to deliver 3 ml of rifampicin. The concentration of rifampicin in 5 ml pleural effusion was measured at 0, 0.5, 1, 2, 4 and 8h after applying EP treatment using high performance liquid chromatography. The measurement data were analyzed by using statistic software SPSS 20.0. The results were expressed by x±s and t test was conducted, with a statistical significance of P<0.05. Results: The average concentration of rifampicin in pleural effusion was (2.2±1.1) μg/ml by oral rifampicin alone. The concentration of rifampicin was (2.7±1.1) μg/ml, (3.0±1.4) μg/ml, (3.2±1.2) μg/ml, (2.8±1.2) μg/ml and (1.3±1.1) μg/ml, respectively, at 0.5 h, 1, 2, 4, 8 h after combining local EP treatment. The results indicated that combining local EP treatment significantly increased the drug concentration in pleural effusion, which lasted for about 5 hours. Conclusions: By applying rifampicin into pleural cavity through EP treatment with penetration of the chest wall, the concentration of rifampicin in pleural effusion of patients with tuberculous pleurisy could be increased. Combined with oral administration of rifampicin, this treatment could prolong the effective drug concentration in pleural effusion, which was beneficial to the bactericidal effects of rifampicin.

NQO1 and CYP450 reductase decrease the systemic exposure of rifampicin-quinone and mediate its redox cycle in rats

Rifampicin (RIF) is used in regimens for infections caused by Mycobacteria accompanied by serious adverse reactions. Rifampicin-quinone (RIF-Q) is a major autoxidation product of RIF. It is not clear whether RIF-Q plays a role in RIF induced adverse reactions. Investigation of the systemic exposure of RIF-Q is helpful to better understand the role of RIF-Q in RIF induced adverse reactions. In this study, a simple and reproducible high performance liquid chromatography-mass spectrometry (LC–MS) method involving a procedure to prevent the RIF from oxidation for simultaneous quantification of RIF and RIF-Q in rat plasma has been developed and validated, and applied to elucidate the systemic exposure of RIF-Q in rats. The pharmacokinetics data showed that the systemic exposure of RIF-Q was very low (0.67% of RIF, AUC0-24) in rats after oral administration of RIF. However, RIF-Q may undergo the redox cycle in vivo by the evidence that the majority of RIF-Q was reduced to RIF after an oral dose of RIF-Q. Pretreatment with the NAD(P)H: quinone oxidoreductase 1 (NQO1) specific inhibitor dicoumarol and/or cytochrome P450 reductase (CPR) inhibitor diphenyleneiodonium suppressed the redox cycle and significantly increased the systemic exposure of RIF-Q. The inhibitors also attenuated the redox cycle induced reactive oxygen species formation and cytotoxicity in RIF-Q-treated HepG2 cells. These results indicate that NQO1 and CPR play an important role in redox cycle of RIF-Q and may thus contribute to RIF-induced adverse reactions.

Effects of inducers of cytochrome P450s on enrofloxacin N-deethylation in crucian carp Carassius auratus gibelio.

In this study with crucian carp (Carassius auratus gibelio), the effect on enrofloxacin (EF) and its metabolite ciprofloxacin (CF) and on the activity of cytochrome P450 1A (CYP1A) and cytochrome P450 3A (CYP3A) was estimated following the oral administration of rifampicin (RIF) (12mg/kg) and β-naphthoflavone (BNF) (12mg/kg), respectively. First, reversed-phase high-performance liquid chromatography (RP-HPLC) was used to detect the pharmacokinetics of EF with continual blood sampling. In RIF-treated, BNF-treated and control groups, the value of the CmaxCF/CmaxEF ratio was 4.41, 0.81 and 0.95, and the corresponding value of the AUC0-t-CF/AUC0-t-EF ratio was 3.69, 1.84 and 1.76, respectively. In the RIF-treated, BNF-treated and control groups, the MRT values of EF were 26.57, 27.45 and 30.88h, and the corresponding values for CF were 5.79, 35.18 and 38.11h, respectively. Based on these results for crucian carp, the accumulation and elimination of EF and CF in the RIF-treated group were more rapid than in BNF-treated and control groups. Second, liver microsomes were pretreated with the inducer of CYP1A for BNF and that of CYP3A for RIF, and then the enzymatic activities of CYP1A and CYP3A were measured, respectively. The activities of ethoxyresorufin-O-deethylation (EROD) and erythromycin-N-demethylation (ERND) increased significantly (P<0.05) for CYP1A and CYP3A, respectively. However, in further experiments on the formation of CF, the level of EF N-deethylation was significantly induced by RIF and inhibited by ketoconazole (KTZ) for CYP3A but had no influence for CYP1A, BNF and berberine chloride (BER). We concluded that CYP3A might be responsible for the N-deethylation of EF and because of this activity, could also serve as a toxicity biomarker in crucian carp.

Pharmacokinetics of Inhaled Rifampicin Porous Particles for Tuberculosis Treatment: Insight into Rifampicin Absorption from the Lungs of Guinea Pigs.

Tuberculosis (TB) is a life-threatening infection that requires a lengthy treatment process that is often associated with adverse effects. Pulmonary delivery of anti-TB drugs has the potential to increase efficacy of treatment by increasing drug concentrations at the lungs, the primary site of infection. The aim of the present study is to evaluate the disposition of rifampicin (RIF) after its pulmonary administration as porous particles (PPs) to guinea pigs and contrast it to that after oral administration. RIF microparticles were prepared by spray drying a solution of RIF and L-leucine (9:1), and the resulting particles were characterized for their physicochemical properties. Animals received RIF either as intravenous solution (iv), as oral suspension of micronized RIF (ORS) and RIF-PPs (ORPP), or by insufflation of the PPs (IRPP). Plasma samples were collected at preselected time points, and bronchoalveolar lavage (BAL) was performed at the end of the study. RIF concentrations in biological samples were analyzed by HPLC. Plasma concentration versus time data was analyzed by compartmental and noncompartmental methods. RIF PPs were thin walled porous particles with mass median aerodynamic diameter (MMAD) of 4.8±0.1 μm, GSD=1.29±0.03, and fine particle fraction below 5.8 μm of 52.9±2.0%. RIF content in the resulting particles was 91.8±0.1%. Plasma concentration vs time profiles revealed that the terminal slope of the iv group was different from that of the oral or pulmonary groups, indicating the possibility of flip-flop kinetics. RIF from IRPP appeared to be absorbed faster than that of ORPP or ORS as evidenced by higher RIF plasma concentrations up until 2 h. Notably, similar AUC (when corrected by dose), similar CL, λ, and half-life were obtained after oral administration of RIF at 40 mg/kg and pulmonary administration of RIF at 20 mg/kg. However, RIF in the IRPP group had a shorter Tmax and higher bioavailability than orally dosed groups. In addition, RIF concentrations in the BAL of animals in the IRPP group were 3-4-fold larger than those in the orally dosed groups. The disposition in ORS and ORPP were best described by a model with two sequential compartments, whereas the disposition of IRPP was best described by a two parallel compartment model. The advantages of delivering RIF by the pulmonary route are demonstrated in the present study. These include achieving higher RIF concentrations in the lungs and similar systemic levels after pulmonary delivery of one-half of the oral nominal dose. This is expected to result in a more effective treatment of pulmonary TB, as shown previously in published efficacy studies.

Limited sampling strategies to predict the area under the concentration-time curve for rifampicin.

Rifampicin (RMP) is the most effective first-line antituberculosis drug. One of the most critical aspects of using it in fixed-drug combination formulations is to ensure it reaches therapeutic levels in blood. The determination of the area under the concentration-time curve (AUC) and appropriate dose adjustment of this drug may contribute to optimization of therapy. Even when the maximal concentration (Cmax) of RMP also predicts its sterilizing effect, the time to reach it (Tmax) takes 40 minutes to 6 hours. The aim of this study was to develop a limited sampling strategy (LSS) for therapeutic drug monitoring assistance for RMP. Full concentration-time curves were obtained from 58 patients with tuberculosis (TB) after the oral administration of RMP in fixed-drug combination formulation. A validated high-performance liquid chromatographic method was used. Pharmacokinetic parameters were estimated with a noncompartmental model. Generalized linear models were obtained by forward steps, and bootstrapping was performed to develop LSS to predict AUC curve from time 0 to the last measured at 24 hours postdose (AUC0-24). The predictive performance of the proposed models was assessed using RMP profiles from 25 other TB patients by comparing predicted and observed AUC0-24. The mean AUC0-24 in the current study was 91.46 ± 36.7 mg·h·L, and the most convenient sampling time points to predict it were 2, 4 and 12 hours postdose (slope [m] = 0.955 ± 0.06; r = 0.92). The mean prediction error was -0.355%, and the root mean square error was 5.6% in the validation group. Alternate LSSs are proposed with 2 of these sampling time points, which also provide good predictions when the 3 most convenient are not feasible. The AUC0-24 for RMP in TB patients can be predicted with acceptable precision through a 2- or 3-point sampling strategy, despite wide interindividual variability. These LSSs could be applied in clinical practice to optimize anti-TB therapy based on therapeutic drug monitoring.

Effects of Pluronic F68 and Labrasol on the intestinal absorption and pharmacokinetics of rifampicin in rats

The aim of this study was to investigate the effects of Pluronic F68 and Labrasol on the intestinal absorption and pharmacokinetics of rifampicin. Intestinal permeability of rifampicin with or without excipients was evaluated by an in situ single-pass perfusion method. A high-performance liquid chromatographic method was applied to study the pharmacokinetics of rifampicin with or without excipients. Labrasol or Pluronic F68 (0.1% and 0.05%, v/v), co-perfused with rifampicin (60 μg/mL), significantly increased in situ permeability. Similarly, verapamil (a typical P-gp inhibitor) also increased in situ permeability, but to a lesser extent. In vivo, the oral administration of rifampicin with or without Pluronic F68, Labrasol or verapamil resulted in statistically significant effect on t(1/2) (4.83 to 7.75, 6.42 and 7.46 h) and total body clearance (0.46 to 0.26, 0.28, 0.24 L/h/kg). In addition, Pluronic F68, Labrasol and verapamil produced minor changes in AUC(0-t), which improved 1.55-, 1.54-, and 1.73-fold in comparison to control group, respectively. These results showed that Labrasol and Pluronic F68 might inhibit the function of P-gp in the intestine, thereby increasing intestinal absorption and changing the pharmacokinetic parameters of rifampicin. Therefore, excipient selection is an important factor to consider in rational formulation design.

Modulation of rifampicin toxicity by 6 MFA, an interferon inducer obtained from fungus Aspergillus ochraceus

The effect of 6 MFA (Sixth mycelial fraction of acetone), an interferon inducer obtained from fungus Aspergillus ochraceus, on rifampicin toxicity was studied in rats. Chronic oral administration of rifampicin (1 g/kg per day) for 30 days produced thrombocytopenia, hemolytic anaemia, transient leukopenia and increased nucleated cells in bone marrow and decreased weights of thymus and spleen significantly in male rats. Furthermore, chronic administration of rifampicin induced significant increase in cytochrome P-450 contents, lipid peroxidation (LPO) and superoxide dismutase (SOD) activity in liver and bone marrow. Simultaneous administration of 6 MFA (100 mg/kg; i.p.) on alternate days for a period of 30 days prevented most of the adverse effects of rifampicin, mentioned earlier and also restored the hepatic architecture histologically. The LPO, cytochrome P 450 content, lymphocyte and bone marrow cell counts returned to normal level whereas SOD activity was further increased. The 6 MFA treatment enhanced the SRBC antibody litre in rifampicin-treated rats. Thus, beneficial effects of 6 MFA in the amelioration of mediated rifampicin toxicity observed in the present study may be through induction of interferons and their associated effects.

Induction of rat liver bilirubin-conjugating enzymes and glutathione S-transferase by rifampicin.

After oral administration of rifampicin and 25-desacetylrifampicin, which is a major metabolite of rifampicin in man but not in rat, to male Wister rats for 7 days, hepatic microsomal cytochrome P450, cytochrome b5, and activities of aniline hydroxylase, aminopyrine demethylase, bilirubin-conjugating enzymes and supernatant glutathione S-transferase were measured. Rifampicin induced bilirubin UDP-glucuronyltransferase, bilirubin UDP-glucosyltransferase, bilirubin UDP-xylosyltransferase and glutathione S-transferase activities, but did not induce mixed function oxidase activities. No inductive effect of desacetylrifampicin on any enzymes was observed. Serum bilirubin increased till the third day, and decreased after 7 days of rifampicin treatment. Plasma clearances of indocyanine green and sulfobromophthalein showed a marked delay after 1 day and 7 days of rifampicin treatment. Induction of bilirubin-conjugating enzymes and glutathione S-transferase by rifampicin in rats was different from that in humans, in which selective induction of mixed function oxidase is reported to occur. This species difference does not seem to be derived from the species difference of rifampicin metabolism, because no effect of desacetylrifampicin was observed. These results suggested that in rats rifampicin directly inhibits the hepatic excretion of bilirubin, whereas it enhances bilirubin conjugation due to enzyme induction.

Pharmacokinetic study of intravenous rifampicin.

The time course of the serum and urine concentrations of rifampicin were evaluated during and after administration of an intravenous preparation of the antibiotic. 300, 450 and 600 mg dose levels of the antibiotic were evaluated, all being given as intravenous infusion after solution in 500 ml of glucose, the infusion lasting 3 h. The results have shown that the serum level curves and the kinetic parameters calculated on them do not differ to any major extent from those corresponding to the same doses given orally. No changes of relevance in the half-life values were observed between doses. Changes in serum bilirubin levels were observed with a pattern similar to that commonly seen with oral administration of rifampicin.