Effect of trimethoprim on the renal clearance of lamivudine in rats

Examination of Urinary Excretion of Unchanged Drug in Humans and Preclinical Animal Models: Increasing the Predictability of Poor Metabolism in Humans

PURPOSE

A dataset of fraction excreted unchanged in the urine (fe) values was developed and used to evaluate the ability of preclinical animal species to predict high urinary excretion, and corresponding poor metabolism, in humans.

METHODS

A literature review of fe values in rats, dogs, and monkeys was conducted for all Biopharmaceutics Drug Disposition Classification System (BDDCS) Class 3 and 4 drugs (n=352) and a set of Class 1 and 2 drugs (n=80). The final dataset consisted of 202 total fe values for 135 unique drugs. Human and animal data were compared through correlations, two-fold analysis, and binary classifications of high (fe ≥30%) versus low (<30%) urinary excretion in humans. Receiver Operating Characteristic curves were plotted to optimize animal fe thresholds.

RESULTS

Significant correlations were found between fe values for each animal species and human fe (p<0.05). Sixty-five percent of all fe values were within two-fold of human fe with animals more likely to underpredict human urinary excretion as opposed to overpredict. Dogs were the most reliable predictors of human fe of the three animal species examined with 72% of fe values within two-fold of human fe and the greatest accuracy in predicting human fe ≥30%. ROC determined thresholds of ≥25% in rats, ≥19% in dogs, and ≥10% in monkeys had improved accuracies in predicting human fe of ≥30%.

CONCLUSIONS

Drugs with high urinary excretion in animals are likely to have high urinary excretion in humans. Animal models tend to underpredict the urinary excretion of unchanged drug in humans.

Drug-drug interactions of a two-drug regimen of dolutegravir and lamivudine for HIV treatment

INTRODUCTION

The GEMINI trials have recently shown that a two-drug regimen of dolutegravir plus lamivudine was non-inferior to a three-drug regimen in HIV-infected naïve patients. Accordingly, it is important that physicians be aware and confident about the drug-drug interactions (DDIs) involving dolutegravir, lamivudine, and other medications. Areas covered: Here, we firstly update the available information on the pharmacokinetic features of dolutegravir and lamivudine; subsequently, the articles mainly deals with the predictable DDIs for both antiretroviral drugs, attempting to underline their clinical implications. This review focuses on the DDIs of dolutegravir/lamivudine combined regimen and, therefore, does not provide an exhaustive list of all the potential DDIs involving the two single agents. A MEDLINE Pubmed search for articles published from January 2000 to December 2018 was completed matching the terms dolutegravir or lamivudine with pharmacokinetics, DDIs, and pharmacology. Moreover, additional studies were identified from the reference list of retrieved articles. Expert opinion: The antiretroviral dual regimen of dolutegravir and lamivudine represents an attractive therapeutic option for HIV in terms of DDIs. This is particularly relevant considering that the population with HIV is aging and is increasingly experience age-related comorbidities, increasing pill burden, polypharmacy and the risk of DDIs.

Efavirenz reduces renal excretion of lamivudine in rats by inhibiting organic cation transporters (OCT, Oct) and multidrug and toxin extrusion proteins (MATE, Mate)

Efavirenz (EFV) is a non-nucleoside reverse transcriptase inhibitor used in first-line combination antiretroviral therapy (cART). It is usually administered with nucleoside reverse transcriptase inhibitors (NRTI), many of which are substrates of OCT uptake solute carriers (SLC22A) and MATE (SLC47A), P-gp (MDR1, ABCB1), BCRP (ABCG2), or MRP2 (ABCC2) efflux transporters. The aim of this study was to evaluate the inhibitory potential of efavirenz towards these transporters and investigate its effects on the pharmacokinetics and tissue distribution of a known Oct/Mate substrate, lamivudine, in rats. Accumulation and transport assays showed that efavirenz inhibits the uptake of metformin by OCT1-, OCT2- and MATE1-expressing MDCK cells and reduces transcellular transport of lamivudine across OCT1/OCT2- and MATE1-expressing MDCK monolayers. Only negligible inhibition of MATE2-K was observed in HEK-MATE2-K cells. Efavirenz also reduced the efflux of calcein from MDCK-MRP2 cells, but had a rather weak inhibitory effect on Hoechst 33342 accumulation in MDCK-MDR1 and MDCK-BCRP cells. An in vivo pharmacokinetic interaction study in male Wistar rats revealed that intravenous injection of efavirenz or the control Oct/Mate inhibitor cimetidine significantly reduced the recovery of lamivudine in urine and greatly increased lamivudine retention in the renal tissue. Co-administration with efavirenz or cimetidine also increased the AUC0-∞ value and reduced total body clearance of lamivudine. These data suggest that efavirenz is a potent inhibitor of OCT/Oct and MATE/Mate transporters. Consequently, it can engage in drug-drug interactions that reduce renal excretion of co-administered substrates and enhance their retention in the kidneys, potentially compromising therapeutic safety.

Renal Drug Transporters and Drug Interactions

Transporters in proximal renal tubules contribute to the disposition of numerous drugs. Furthermore, the molecular mechanisms of tubular secretion have been progressively elucidated during the past decades. Organic anions tend to be secreted by the transport proteins OAT1, OAT3 and OATP4C1 on the basolateral side of tubular cells, and multidrug resistance protein (MRP) 2, MRP4, OATP1A2 and breast cancer resistance protein (BCRP) on the apical side. Organic cations are secreted by organic cation transporter (OCT) 2 on the basolateral side, and multidrug and toxic compound extrusion (MATE) proteins MATE1, MATE2/2-K, P-glycoprotein, organic cation and carnitine transporter (OCTN) 1 and OCTN2 on the apical side. Significant drug-drug interactions (DDIs) may affect any of these transporters, altering the clearance and, consequently, the efficacy and/or toxicity of substrate drugs. Interactions at the level of basolateral transporters typically decrease the clearance of the victim drug, causing higher systemic exposure. Interactions at the apical level can also lower drug clearance, but may be associated with higher renal toxicity, due to intracellular accumulation. Whereas the importance of glomerular filtration in drug disposition is largely appreciated among clinicians, DDIs involving renal transporters are less well recognized. This review summarizes current knowledge on the roles, quantitative importance and clinical relevance of these transporters in drug therapy. It proposes an approach based on substrate-inhibitor associations for predicting potential tubular-based DDIs and preventing their adverse consequences. We provide a comprehensive list of known drug interactions with renally-expressed transporters. While many of these interactions have limited clinical consequences, some involving high-risk drugs (e.g. methotrexate) definitely deserve the attention of prescribers.

Role of organic cation transporter OCT2 and multidrug and toxin extrusion proteins MATE1 and MATE2-K for transport and drug interactions of the antiviral lamivudine

The antiviral lamivudine is cleared predominantly by the kidney with a relevant contribution of renal tubular secretion. It is not clear which drug transporters mediate lamivudine renal secretion. Our aim was to investigate lamivudine as substrate of the renal drug transporters organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins MATE1 and MATE2-K. Uptake experiments were performed in OCT2, MATE1, or MATE2-K single-transfected human embryonic kidney 293 (HEK) cells. Transcellular transport experiments were performed in OCT2 and/or MATE1 single- or double-transfected Madin-Darby canine kidney II (MDCK) cells grown on transwell filters. Lamivudine uptake was significantly increased in HEK-OCT2, HEK-MATE1, and HEK-MATE2-K cells compared to control cells. In transcellular experiments, OCT2 located in the basolateral membrane had no effect on transcellular lamivudine transport. MATE1 located in the apical membrane decreased intracellular concentrations and increased transcellular transport of lamivudine from the basal to the apical compartment. MATE1- or MATE2-K-mediated transport was increased by an oppositely directed pH gradient. Several simultaneously administered drugs inhibited OCT2- or MATE2-K-mediated lamivudine uptake. The strongest inhibitors were carvedilol for OCT2 and trimethoprim for MATE2-K (inhibition by 96.3 and 83.7% at 15 μM, respectively, p<0.001). Trimethoprim inhibited OCT2- and MATE2-K-mediated lamivudine uptake with IC₅₀ values of 13.2 and 0.66 μM, respectively. Transcellular lamivudine transport in OCT2-MATE1 double-transfected cells was inhibited by trimethoprim with an IC₅₀ value of 6.9 μM. Lamivudine is a substrate of renal drug transporters OCT2, MATE1, and MATE2-K. Concomitant administration of drugs that inhibit these transporters could decrease renal clearance of lamivudine.

P-glycoprotein (P-gp) in the monogonont rotifer, Brachionus koreanus: molecular characterization and expression in response to pharmaceuticals

P-glycoprotein is involved in the efflux of diverse chemicals, including hydrophobic compounds and pharmaceuticals as a first line of defense. Here, we firstly identified and characterized the P-gp (Bk-P-gp) gene in the rotifer, Brachionus koreanus. Bk-P-gp was highly conserved in genomic organization compared to the human P-gp gene. Messenger RNA expression of Bk-P-gp revealed that it would be regulated by temperature change via 14 heat shock response elements in its promoter region. Bk-P-gp showed a high similarity of motifs/domains compared to those of vertebrates in its amino acid sequences. To check whether Bk-P-gp would be inducible, we exposed B. koreanus to six pharmaceuticals including antibiotics for use in aquaculture and observed dose- and time-dependency on transcripts of Bk-P-gp for 24h over a wide range of concentration. Efflux assay and membrane topology supported its conserved function for transportation of a number of chemicals upon cellular damage. To reveal the effect of pharmaceuticals on the rotifer, we measured survival rate and population growth rate after exposure to six pharmaceuticals. In an acute toxicity test, both NOEC and LC₅₀ values for all the pharmaceuticals were high for 24 h. ATP, CBZ, SMX, and TMP markedly inhibited the population growth of B. koreanus after exposure up to 100 mg/L for 10 days. In this paper, we demonstrated that various pharmaceuticals can retard growth rate with up-regulation of the P-gp gene as a cellular defense system. This finding provides a better understanding of molecular mechanisms involved in pharmaceutical-mediated cellular damage in B. koreanus.

Molecular mechanism of renal tubular secretion of the antimalarial drug chloroquine

The antimalarial drug chloroquine is eliminated to a significant extent by renal tubular secretion. The molecular mechanism of renal chloroquine secretion remains unknown. We hypothesized that organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1), localized in the basolateral and luminal membranes of proximal tubule cells, respectively, are involved in chloroquine transport. The interaction of chloroquine with both transporters was investigated using single-transfected human embryonic kidney 293 (HEK293)-MATE1 cells in uptake experiments and single-transfected Madin-Darby canine kidney II (MDCK)-OCT2 and MDCK-MATE1 cells as well as double-transfected MDCK-OCT2-MATE1 cells grown as polarized monolayers on transwell filters. In HEK293-MATE1 cells, chloroquine competitively inhibited MATE1-mediated metformin uptake (K(i) = 2.8 μM). Cellular accumulation of chloroquine was significantly lower (P < 0.001) and transcellular chloroquine transport was significantly increased (P < 0.001) in MDCK-MATE1 and MDCK-OCT2-MATE1 cells compared to vector control cells after basal addition of chloroquine (0.1 to 10 μM). In contrast, no difference in cellular accumulation or transcellular transport of chloroquine was observed between MDCK-OCT2 and vector control cells. In line with an oppositely directed proton gradient acting as a driving force for MATE1, basal-to-apical transport of chloroquine by MDCK-OCT2-MATE1 cells increased with decreasing apical pH from 7.8 to 6.0. Transcellular transport of chloroquine by MDCK-OCT2-MATE1 cells was inhibited by cimetidine, trimethoprim, and amitriptyline. Our data demonstrate that chloroquine is a substrate and potent competitive inhibitor of MATE1, whereas OCT2 seems to play no role in chloroquine uptake. Concomitantly administered MATE1 inhibitors are likely to modify the renal secretion of chloroquine.

Evaluation of steady-state pharmacokinetic interactions between ritonavir-boosted BILR 355, a non-nucleoside reverse transcriptase inhibitor, and lamivudine/zidovudine in healthy subjects

WHAT IS KNOWN AND OBJECTIVE

BILR 355 is a second generation non-nucleoside reverse transcriptase inhibitor. It has shown promising in vitro anti-HIV-1 activities and favourable human pharmacokinetic properties after co-administration with ritonavir (RTV). Lamivudine (3TC) is a nucleoside reverse transcriptase inhibitor. It is excreted predominantly in urine by a transporter-mediated pathway. These two drugs are likely to be given together to HIV-infected patients. The objective of this study was to investigate any steady-state pharmacokinetic interactions between RTV-boosted BILR 355 and 3TC/zidovudine (ZDV).

METHODS

This was a randomized, open label, prospective study. In group A, 39 healthy subjects were given 3TC/ZDV (150 mg/300 mg) twice daily (b.i.d.) for 7 days, and then BILR 355 and RTV (BILR 355/r, 150 mg/100 mg) were co-administered with this regimen for an additional 7 days. Intensive blood samples were taken on days 7 and 14 for pharmacokinetic assessments. In group B, 12 healthy subjects were given BILR 355/r (150 mg/100 mg) b.i.d. for 7 days. The pharmacokinetic data from group B were pooled with data from group B subjects in other similar studies performed in parallel (BILR 355 alone group in BILR 355 drug-drug interaction studies with tipranavir, lopinavir/RTV, and emtricitabine/tenofovir DF; BILR 355 regimen was the same).

RESULTS AND DISCUSSION

After co-administration with BILR 355/r, the AUC(12,ss) and C(max,ss) of 3TC increased by 45% and 24%, respectively; the elimination half-life (t(1/2) ,ss) of 3TC was significantly increased. However, the pharmacokinetics of ZDV was unchanged. Co-administration with 3TC/ZDV resulted in a 22% decrease in AUC(12,ss) and a 20% decrease in C(max,ss) for BILR 355. The observed increase in exposure and prolongation of t(1/2,ss) of 3TC is potentially related to inhibition of OCT-mediated urinary excretion of 3TC.

WHAT IS NEW AND CONCLUSION

Concomitant administration of BILR 355 with 3TC/ZDV resulted in a modest decrease in exposure to BILR 355 and a 45% increase in exposure to 3TC.

Transport of lamivudine [(-)-beta-L-2',3'-dideoxy-3'-thiacytidine] and high-affinity interaction of nucleoside reverse transcriptase inhibitors with human organic cation transporters 1, 2, and 3

Nucleoside reverse transcriptase inhibitors (NRTIs) need to enter cells to act against the HIV-1. Human organic cation transporters (hOCT1-3) are expressed and active in CD4+ T cells, the main target of HIV-1, and have been associated with antiviral uptake in different tissues. In this study, we examined whether NRTIs interact and are substrates of hOCT in cells stably expressing these transporters. Using [(3)H]N-methyl-4-phenylpyridinium, we found a high-affinity interaction among abacavir [[(1S,4R)-4-[2-amino-6-(cyclopropylamino)purin-9-yl]-cyclopent-2-enyl]methanol sulfate] (ABC); <0.08 nM], azidothymidine [3'-azido-3'-deoxythymidine (AZT); <0.4 nM], tenofovir disoproxil fumarate (<1.0 nM), and emtricitabine (<2.5 nM) and hOCTs. Using a wide range of concentrations of lamivudine [(-)-beta-L-2',3'-dideoxy-3'-thiacyitidine (3TC)], we determined two different binding sites for hOCTs: a high-affinity site (K(d1) = 12.3-15.4 pM) and a low-affinity site (K(d2) = 1.9-3.4 mM). Measuring direct uptake of [(3)H]3TC and inhibition with hOCT substrates, we identified 3TC as a novel substrate for hOCT1, 2, and 3, with hOCT1 as the most efficient transporter (K(m) = 1.25 +/- 0.1 mM; V(max) = 10.40 +/- 0.32 nmol/mg protein/min; V(max)/K(m) = 8.32 +/- 0.40 microl/mg protein/min). In drug-drug interaction experiments, we analyzed cis-inhibition of [(3)H]3TC uptake by ABC and AZT and found that 40 to 50% was inhibited at low concentrations of the drugs (K(i) = 22-500 pM). These data reveal that NRTIs experience a high-affinity interaction with hOCTs, suggesting a putative role for these drugs as modulators of hOCT activity. Finally, 3TC is a novel substrate for hOCTs and the inhibition of its uptake at low concentrations of ABC and AZT could have implications for the pharmacokinetics of 3TC.

Relevance of the organic cation transporters 1 and 2 for antiretroviral drug therapy in human immunodeficiency virus infection

Carrier-mediated transport across cell membranes is an important determinant of activity, resistance, and toxicity of chemotherapeutic agents including antiretroviral (ARV) drugs (ARDs). The organic cation transporters (OCTs) 1 and 2 have been implicated in the translocation of different cationic drugs but so far were insufficiently tested for interactions with ARDs. Here, we assessed among cationic drugs commonly used in human immunodeficiency virus (HIV) therapy inhibitors and substrates of OCTs, and analyzed the tissue distribution of OCTs and their expression in lymph nodes (LNs), the primary intracellular target of HIV and ARDs. Inhibitors were identified by measuring the attenuated uptake of the radiolabeled model substrate 1-methyl-4-phenylpyridinium into OCT-transfected human embryonic kidney-293 cells in the presence of ARDs. Substrates were identified by measuring OCT-specific intracellular accumulation using liquid chromatography/tandem mass spectrometry. Inhibitory drugs were (in order of increasing potency): nelfinavir < ritonavir < saquinavir < indinavir < trimethoprim < pentamidine, with consistently lower IC(50) values determined for OCT1. Substrates with highest transport efficacy (V(max)/K(m)) were lamivudine (OCT1, 8 microl/mg protein/min; OCT2, 4.4 microl/mg protein/min) and zalcitabine (OCT1, 4.1 microl/mg protein/min; OCT2, 2.6 microl/mg protein/min). Using quantitative real-time polymerase chain reaction, a marked expression level of OCT1 was detected in human samples of liver, ovary, prostate, and testis, and of OCT2 in kidney, colon, heart, skeletal muscle, and testis. Expression of OCTs in LNs was low in HIV-negative control individuals but dramatically increased in HIV-infected persons. These data suggest that drug interactions about the OCTs may be relevant for the ARV therapy, in particular by influencing drug accession to infected tissues and hepatic or renal elimination.

Renal excretion mechanisms of the antiviral nucleoside analogue AM 188 IN the rat isolated perfused kidney

1. AM 188 is an antiviral guanosine analogue that undergoes extensive renal excretion in humans. The present study was designed to investigate the disposition of AM 188 over a range of concentrations in the rat isolated perfused kidney (IPK) to explore the mechanisms involved in its renal handling. 2. Right kidneys of male Sprague-Dawley rats (n = 23) were isolated and perfused in recirculating mode with Krebs'-Henseleit (pH 7.4) buffer containing 0.65% bovine serum albumin, 3.6% dextran, amino acids and glucose. [14C]-Inulin was added to the perfusate reservoir to permit estimation of glomerular filtration rate (GFR). [3H]-AM 188 and unlabelled AM 188 were added to the perfusate as a bolus initially, followed by a constant rate of infusion at 5, 25, 125, 500 or 1000 microg/min to achieve initial target perfusate concentrations of 1, 5, 25, 100 or 200 microg/mL, respectively. During the 130 min over which AM 188 was infused, urine was collected in 10 min intervals (commencing 10 min after the bolus dose) and perfusate was collected at the mid-point of these intervals to permit calculation of the renal clearance (CLR) of AM 188. Binding of AM 188 in perfusate, measured using ultrafiltration, was negligible. 3. The bolus dose and infusion regimen produced relatively stable AM 188 concentrations in perfusate in the 5, 25 and 125 micro g/min groups and progressively increasing concentrations in the 500 and 1000 microg/min groups. High-pressure liquid chromatography analysis of IPK perfusate and urine suggested that there was no or negligible metabolism of AM 188 in the kidney. The CLR/GFR ratio for AM 188 (mean+/-SD) was 5.76 +/- 1.57, 5.99 +/- 0.52, 6.02 +/- 1.47, 3.38 +/- 0.26 and 1.08 +/- 0.42 in the 5, 25, 125, 500 and 1000 microg/min groups, respectively, showing significant reductions at the two highest infusion rates (P < 0.05). Although there was no difference between the five groups in the distribution of AM 188 between kidney tissue and perfusate (KT/P), at the end of perfusion the corresponding urine-to-tissue concentration ratio declined significantly in the 1000 microg/min group. 4. AM 188 undergoes substantial net renal secretion over a wide range of perfusate concentrations. A reduction in renal clearance at perfusate concentrations above 25 microg/mL could be due to saturation of carrier-mediated transport at the brush border membrane and/or a solubility limitation leading to precipitation of AM 188 in tubular cells and/or tubular urine.

Uptake of lamivudine by rat renal brush border membrane vesicles

Uptake of lamivudine, a nucleoside analogue antiviral agent, by brush border membrane vesicles (BBMV) prepared from rat renal cortex was investigated. Initial uptake of lamivudine by BBMV was stimulated in the presence of an outward pH gradient. Determination of the kinetic parameters of the initial uptake yielded apparent Km and Vmax values of 2.28 mm and 1.56 nmol (mg protein)(-1) (20 s)(-1), respectively. The pH-driven uptake of lamivudine was inhibited by organic cations such as trimethoprim and cimetidine. The inhibitory effect of trimethoprim on lamivudine uptake was competitive, with an apparent Ki of 27.6 microM. The uptake of lamivudine was also inhibited by nitrobenzylthioinosine, a representative inhibitor of nucleoside transport, and by other nucleoside analogues, such as azidothymidine and dideoxycytidine, that are excreted by renal tubular secretion. These findings suggest that efflux of lamivudine at the brush border membrane of renal tubular epithelium is mediated by an H+/lamivudine antiport system, which may correspond to the H+/organic cation antiport system, and that this system is also involved in the renal secretion of other nucleoside analogues.