Cardiovascular drugs and COVID-19 clinical outcomes: a systematic review and meta-analysis of randomized controlled trials.

AIMS: To update our previously reported systematic review and meta-analysis of observational studies on cardiovascular drug exposure and COVID-19 clinical outcomes by focusing on newly published randomized controlled trials (RCTs). METHODS: More than 500 databases were searched between 1 November 2020 and 2 October 2021 to identify RCTs that were published after our baseline review. One reviewer extracted data with other reviewers verifying the extracted data for accuracy and completeness. RESULTS: After screening 22 414 records, we included 24 and 21 RCTs in the qualitative and quantitative syntheses, respectively. The most investigated drug classes were angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blocker (ARBs) and anticoagulants, investigated by 10 and 11 studies respectively. In meta-analyses, ACEI/ARBs did not affect hospitalization length (mean difference -0.42, 95% confidence interval [CI] -1.83; 0.98 d, n = 1183), COVID-19 severity (risk ratio/RR 0.90, 95% CI 0.71; 1.15, n = 1661) or mortality (risk ratio [RR] 0.92, 95% CI 0.58; 1.47, n = 1646). Therapeutic anticoagulation also had no effect (hospitalization length mean difference -0.29, 95% CI -1.13 to 0.56 d, n = 1449; severity RR 0.86, 95% CI 0.70; 1.04, n = 2696; and, mortality RR 0.93, 95% CI 0.77; 1.13, n = 5689). Other investigated drug classes were antiplatelets (aspirin, 2 trials), antithrombotics (sulodexide, 1 trial), calcium channel blockers (amlodipine, 1 trial) and lipid-modifying drugs (atorvastatin, 1 trial). CONCLUSION: Moderate- to high-certainty RCT evidence suggests that cardiovascular drugs such as ACEIs/ARBs are not associated with poor COVID-19 outcomes, and should therefore not be discontinued. These cardiovascular drugs should also not be initiated to treat or prevent COVID-19 unless they are needed for an underlying currently approved therapeutic indication.

Cardiovascular drugs and COVID-19 clinical outcomes: A living systematic review and meta-analysis.

AIMS: The aim of this study was to continually evaluate the association between cardiovascular drug exposure and COVID-19 clinical outcomes (susceptibility to infection, disease severity, hospitalization, hospitalization length, and all-cause mortality) in patients at risk of/with confirmed COVID-19. METHODS: Eligible publications were identified from more than 500 databases on 1 November 2020. One reviewer extracted data with 20% of the records independently extracted/evaluated by a second reviewer. RESULTS: Of 52 735 screened records, 429 and 390 studies were included in the qualitative and quantitative syntheses, respectively. The most-reported drugs were angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs) with ACEI/ARB exposure having borderline association with confirmed COVID-19 infection (OR 1.14, 95% CI 1.00-1.31). Among COVID-19 patients, unadjusted estimates showed that ACEI/ARB exposure was associated with hospitalization (OR 1.76, 95% CI 1.34-2.32), disease severity (OR 1.40, 95% CI 1.26-1.55) and all-cause mortality (OR 1.22, 95% CI 1.12-1.33) but not hospitalization length (mean difference -0.27, 95% CI -1.36-0.82 days). After adjustment, ACEI/ARB exposure was not associated with confirmed COVID-19 infection (OR 0.92, 95% CI 0.71-1.19), hospitalization (OR 0.93, 95% CI 0.70-1.24), disease severity (OR 1.05, 95% CI 0.81-1.38) or all-cause mortality (OR 0.84, 95% CI 0.70-1.00). Similarly, subgroup analyses involving only hypertensive patients revealed that ACEI/ARB exposure was not associated with confirmed COVID-19 infection (OR 0.93, 95% CI 0.79-1.09), hospitalization (OR 0.84, 95% CI 0.58-1.22), hospitalization length (mean difference -0.14, 95% CI -1.65-1.36 days), disease severity (OR 0.92, 95% CI 0.76-1.11) while it decreased the odds of dying (OR 0.76, 95% CI 0.65-0.88). A similar trend was observed for other cardiovascular drugs. However, the validity of these findings is limited by a high level of heterogeneity and serious risk of bias. CONCLUSION: Cardiovascular drugs are not associated with poor COVID-19 outcomes in adjusted analyses. Patients should continue taking these drugs as prescribed.

TAILoR (TelmisArtan and InsuLin Resistance in Human Immunodeficiency Virus [HIV]): An Adaptive-design, Dose-ranging Phase IIb Randomized Trial of Telmisartan for the Reduction of Insulin Resistance in HIV-positive Individuals on Combination Antiretroviral Therapy.

BACKGROUND: Combination antiretroviral therapy results in metabolic abnormalities which increase cardiovascular disease risk. We evaluated whether telmisartan reduces insulin resistance in human immunodeficiency virus (HIV)-positive individuals on antiretrovirals. METHODS: We conducted a multicenter, randomized, open-label, dose-ranging controlled trial of telmisartan. Participants with HIV infection receiving combination antiretroviral therapy were randomized equally to either no intervention (control) or 20, 40, or 80 mg telmisartan once daily. The adaptive design allowed testing of all dose(s) of telmisartan in stage I, with the promising dose(s) being taken into stage II. The primary outcome measure was reduction in homeostasis model assessment of insulin resistance (HOMA-IR) at 24 weeks. RESULTS: A total of 377 patients were recruited. In stage I, 48, 49, 47, and 45 patients were randomized to control and 20, 40, and 80 mg telmisartan, respectively (total n = 189). At the interim analysis, 80 mg telmisartan was taken forward into stage II. At the end of stage II (n = 105, control; 106, 80-mg arm), there were no differences in HOMA-IR (estimated effect, 0.007; SE, 0.106) at 24 weeks between the telmisartan (80 mg) and nonintervention arms. Longitudinal analysis over 48 weeks showed no change in HOMA-IR, lipid or adipokine levels. There were significant (P ≤ .05), but marginal, improvements in revised Quantitative Insulin Sensitivity Check Index (QUICKI) (0.004) and plasma hs-CRP (-0.222 mg/L) and reduction in liver fat content (1.714 mean reduction; P = .005). CONCLUSIONS: No significant effect of telmisartan was demonstrated on the primary outcome (HOMA-IR), but there were marginal improvements with some secondary outcome measures. Further studies in this population are warranted to identify novel strategies for preventing cardiovascular morbidity and mortality. CLINICAL TRIAL REGISTRATION: ISRCTN registry (51069819).

Drug repurposing: progress, challenges and recommendations.

Given the high attrition rates, substantial costs and slow pace of new drug discovery and development, repurposing of 'old' drugs to treat both common and rare diseases is increasingly becoming an attractive proposition because it involves the use of de-risked compounds, with potentially lower overall development costs and shorter development timelines. Various data-driven and experimental approaches have been suggested for the identification of repurposable drug candidates; however, there are also major technological and regulatory challenges that need to be addressed. In this Review, we present approaches used for drug repurposing (also known as drug repositioning), discuss the challenges faced by the repurposing community and recommend innovative ways by which these challenges could be addressed to help realize the full potential of drug repurposing.

Telmisartan reverses antiretroviral-induced adipocyte toxicity and insulin resistance in vitro.

BACKGROUND: Antiretroviral therapy in HIV-positive patients leads to insulin resistance which is central to the pathogenesis of various metabolic abnormalities and cardiovascular disease seen in this patient group. We have investigated the dose-response relationship of telmisartan, an antihypertensive, on adipocytes in vitro in order to determine whether it may have metabolic beneficial effects. METHODS: Using in vitro chronic toxicity models (3T3-F442A murine and primary human adipocytes), we evaluated the effects of different concentrations of telmisartan on adipocyte differentiation and adipogenic gene expression using lipid accumulation assays and real-time polymerase chain reaction, respectively. Adipokine secretion and expression of insulin signalling mediators were evaluated using enzyme-linked immunosorbent assays. RESULTS: Telmisartan partially reversed the deleterious effects of antiretrovirals on adipocyte lipid accumulation, expression of adipogenic regulators (peroxisome proliferator receptor-gamma and lipin 1), adipokine secretion and expression of the insulin signalling mediator pAktSer473. The metabolic effects of telmisartan followed a non-monotonic response with the maximal effect observed at 5 µM in the primary human adipocyte model. CONCLUSION: Telmisartan has beneficial metabolic effects in adipocytes in vitro, but its potential to reduce antiretroviral-induced cardiometabolic disease in HIV-infected individuals needs to be evaluated in a well-designed adequately powered clinical trial.

Telmisartan and Insulin Resistance in HIV (TAILoR): protocol for a dose-ranging phase II randomised open-labelled trial of telmisartan as a strategy for the reduction of insulin resistance in HIV-positive individuals on combination antiretroviral therapy.

INTRODUCTION: Telmisartan, an angiotensin receptor blocker, has beneficial effects on insulin resistance and cardiovascular health in non-HIV populations. This trial will evaluate whether telmisartan can reduce insulin resistance in HIV-positive individuals on combination antiretroviral therapy. METHODS AND ANALYSIS: This is a phase II, multicentre, randomised, open-labelled, dose-ranging trial of telmisartan in 336 HIV-positive individuals over a period of 48 weeks. The trial will use an adaptive design to inform the optimal dose of telmisartan. Patients will be randomised initially 1:1:1:1 to receive one of the three doses of telmisartan (20, 40 and 80 mg) or no intervention (control). An interim analysis will be performed when half of the planned maximum of 336 patients have been followed up for at least 24 weeks. The second stage of the study will depend on the results of interim analysis. The primary outcome measure is a reduction in insulin resistance (as measured by Homeostatic Model Assessment-Insulin Resistance (HOMA-IR)) in telmisartan treated arm(s) after 24 weeks of treatment in comparison with the non-intervention arm. The secondary outcome measures include changes in lipid profile; body fat redistribution (as measured by MRI); plasma and urinary levels of various biomarkers of cardiometabolic and renal health at 12, 24 and 48 weeks. Serious adverse events will be compared between different telmisartan treated dose arm(s) and the control arm. ETHICS AND DISSEMINATION: The study, this protocol and related documents have been approved by the National Research Ethics Service Committee North West-Liverpool Central (Ref: 12/NW/0214). On successful completion, study data will be shared with academic collaborators. The findings from TAILoR will be disseminated through peer-reviewed publications, at scientific conferences, the media and through patient and public involvement. TRIAL REGISTRATION NUMBERS: 04196/0024/001-0001; EUDRACT: 2012-000935-18; ISRCTN: 51069819.

Institutional profile: the Wolfson Centre for Personalised Medicine, University of Liverpool, Liverpool, UK.

The Wolfson Centre for Personalised Medicine is part of the Institute of Translational Medicine at the University of Liverpool (Liverpool, UK). It houses a multidisciplinary team of personalized medicine researchers engaged in collaborative research with partners across the globe. The primary focus of the centre is the identification of predictive biomarkers of drug safety and efficacy with the aim of translation from 'bench-to-bedside'. Studies utilizing the latest genotyping and phenotyping, and point-of-care technologies, are undertaken with the ultimate aim of developing easy access for patients to truly personalized medicine. In addition to translation into clinical practice, the Centre puts significant emphasis into education of clinicians and scientists alike, as well as public engagement activities to promote personalized medicine.

RXRγ gene variants are associated with HIV lipodystrophy.

HIV lipodystrophy (HIVLD), associated with combination antiretroviral therapy (cART), leads to metabolic and cardiovascular diseases. Nuclear receptors play a central role in lipid homoeostasis and drug disposition; their genetic variants may predispose an individual to the development of HIVLD. DNA samples obtained from cART-treated HIV-positive patients with (HIVLD+; 124) and without (HIVLD-; 56) HIVLD were genotyped for 77 single nucleotide polymorphisms in nine nuclear receptor genes. Statistical analysis was carried out using Haploview software and by logistic regression. Three single nucleotide polymorphisms in RXRγ (rs2134095, rs113471, rs2194899) and its haplotypes (HIVLD+, 54%; HIVLD-, 40.6%; P=0.02) showed significant association with HIVLD. Multivariate analysis identified time since diagnosis (P=0.001) and carriage of the RXRγ haplotype (P=0.02) to be independently associated with HIVLD. Genetic variation in RXRγ, a common binding partner of nuclear receptors that modulate lipid homoeostasis and drug disposition, may contribute to the development of HIVLD in cART-treated HIV patients. These results need replication in other cohorts.

Simultaneous pharmacogenetics-based population pharmacokinetic analysis of darunavir and ritonavir in HIV-infected patients.

BACKGROUND: Darunavir is a potent protease inhibitor of HIV. To enhance its pharmacokinetic profile, darunavir must be co-administered with ritonavir. There is wide inter-patient variability in darunavir pharmacokinetics among HIV-infected individuals, however. Darunavir is a known substrate for influx transporters, such as the 1A2 and the 1B1 members of the solute carrier organic anion transporter family (SLCO1A2, SLCO1B1), as well as for efflux transporters such as the multi-drug resistance protein 1 (MRP1). OBJECTIVE: The aim of this study was to develop a semi-mechanistic population pharmacokinetic model for darunavir and ritonavir administered in HIV-infected adults. The desired model would incorporate patient characteristics and pharmacogenetic data contributing to variability in drug concentrations and also take into account the interaction between the two compounds. METHODS: A population pharmacokinetic analysis was performed with 705 plasma samples from 75 Caucasian individuals receiving darunavir/ritonavir (600/100 mg twice daily) for at least 4 weeks. At least one full pharmacokinetic profile was obtained for each participant, and darunavir and ritonavir concentrations in plasma were determined by high performance liquid chromatography. Genotyping for 148 polymorphisms in genes coding for transporters or metabolizing enzymes was conducted by two methods: MALDI-TOF mass spectrometry and real-time polymerase chain reaction-based allelic discrimination. A population pharmacokinetic model was developed for darunavir and for ritonavir. The effect of single nucleotide polymorphisms on the post hoc individual pharmacokinetic parameters was first explored using graphic methods and regression analysis. Those covariates related to changes in darunavir or ritonavir pharmacokinetic parameters were then further evaluated using non-linear mixed effects modeling (NONMEM version VII). RESULTS: Darunavir and ritonavir pharmacokinetics were best described by a two- and one-compartment model, respectively, both with first-order absorption and elimination. The darunavir peripheral volume of distribution decreased as α1-acid glycoprotein concentrations increased. Darunavir clearance was 12 % lower in patients with SLCO3A1 rs8027174 GT/TT genotypes, while homozygosity for the rs4294800 A allele was associated with 2.5-fold higher central volume of distribution. Body weight influenced ritonavir clearance. Ritonavir inhibited darunavir clearance following a maximum-effect model. CONCLUSION: A population pharmacokinetic model to simultaneously describe the pharmacokinetics of darunavir and ritonavir was developed in HIV-infected patients. The model provides better understanding of the interaction between darunavir and ritonavir and suggests an association between SLCO3A1 polymorphisms and darunavir pharmacokinetics. Bayesian estimates of individual darunavir parameters and ritonavir may be useful to predict darunavir exposure.

The hOCT1 SNPs M420del and M408V alter imatinib uptake and M420del modifies clinical outcome in imatinib-treated chronic myeloid leukemia.

Although the prognosis of chronic myeloid leukemia (CML) patients treated with imatinib is good, many fail to develop an optimal response or lose one. This heterogeneity could be attributed to the presence of human organic cation transporter-1 (hOCT1) single nucleotide polymorphisms (SNPs). In the present study, we analyzed the effect of 23 hOCT1 SNPs on imatinib treatment outcome in newly diagnosed CML patients using MassARRAY sequencing and pyrosequencing. The only SNP associated with outcome was M420del (rs35191146), with patients with the M420del demonstrating an increased probability of imatinib treatment failure. In CML cell lines transfected with M420del and/or M408V, M420del significantly decreased imatinib uptake, but this effect was countered if the M408V (rs628031) SNP was also present. A similar effect was seen for the uptake of the hOCT1 substrates TEA(+) and ASP(+). Finally, apparent hOCT1 mRNA levels were studied using both our earlier primers covering the M420del and another set that did not. Different mRNA expression was observed, explaining the disparity in published data on the prognostic importance of hOCT1 mRNA and highlighting the importance of avoiding common SNP sites in primer design. These data demonstrate that the common M420del SNP can modulate the outcome of imatinib treatment.

Improved glycaemia correlates with liver fat reduction in obese, type 2 diabetes, patients given glucagon-like peptide-1 (GLP-1) receptor agonists.

Glucagon-like peptide-1 receptor agonists (GLP-1 RA) are effective for obese patients with type 2 diabetes mellitus (T2DM) because they concomitantly target obesity and dysglycaemia. Considering the high prevalence of non-alcoholic fatty liver disease (NAFLD) in patients with T2DM, we determined the impact of 6 months' GLP-1 RA therapy on intrahepatic lipid (IHL) in obese, T2DM patients with hepatic steatosis, and evaluated the inter-relationship between changes in IHL with those in glycosylated haemoglobin (HbA(1)c), body weight, and volume of abdominal visceral and subcutaneous adipose tissue (VAT and SAT). We prospectively studied 25 (12 male) patients, age 50±10 years, BMI 38.4±5.6 kg/m(2) (mean ± SD) with baseline IHL of 28.2% (16.5 to 43.1%) and HbA(1)c of 9.6% (7.9 to 10.7%) (median and interquartile range). Patients treated with metformin and sulphonylureas/DPP-IV inhibitors were given 6 months GLP-1 RA (exenatide, n = 19; liraglutide, n = 6). IHL was quantified by liver proton magnetic resonance spectroscopy ((1)H MRS) and VAT and SAT by whole body magnetic resonance imaging (MRI). Treatment was associated with mean weight loss of 5.0 kg (95% CI 3.5,6.5 kg), mean HbA(1c) reduction of 1·6% (17 mmol/mol) (0·8,2·4%) and a 42% relative reduction in IHL (-59.3, -16.5%). The relative reduction in IHL correlated with that in HbA(1)c (ρ = 0.49; p = 0.01) but was not significantly correlated with that in total body weight, VAT or SAT. The greatest IHL reduction occurred in individuals with highest pre-treatment levels. Mechanistic studies are needed to determine potential direct effects of GLP-1 RA on human liver lipid metabolism.

Association of ABCC10 polymorphisms with nevirapine plasma concentrations in the German Competence Network for HIV/AIDS.

BACKGROUND: Nevirapine exhibits marked interpatient variability in pharmacokinetics. CYP2B6 activity and demographic factors are important, but there are a few data on drug transporters for nevirapine. ABCC10 (MRP7) is an efflux transporter highly expressed in liver, intestine, and peripheral blood cells. We investigated whether nevirapine is a substrate for ABCC10 and whether genetic variants contribute to variability in nevirapine plasma concentrations. METHODS: Accumulation of nevirapine was assessed in parental and ABCC10-transfected HEK293 cells (HEK293-ABCC10), CD4+ cells, and monocyte-derived macrophages from healthy volunteers (n=8). ABCC10 small interfering RNA studies were also conducted. DNA samples with paired plasma drug concentrations were available from 163 HIV-infected patients receiving nevirapine-containing regimens. Sequenom was used to screen 14 single nucleotide polymorphisms in ABCC10. Linear regression models were used to identify factors independently associated with nevirapine plasma concentration. RESULTS: Nevirapine accumulation was 37% lower in HEK293-ABCC10 cells compared with parental HEK293 cells (P=0.02), and this was reversed by cepharanthine (an ABCC10 inhibitor). After small interfering RNA knockdown of ABCC10, there was an increase in accumulation of nevirapine in CD4 cells (32%; P=0.03) and monocyte-derived macrophages (38%; P=0.04). Marked differences in the haplotype structure of ABCC10 was observed between White and Black patients in the cohort. In Whites, an exonic single nucleotide polymorphism (rs2125739) was significantly associated with nevirapine plasma concentration (P=0.02). Multivariate regression analysis identified carriage of a composite genotype of ABCC10 rs2125739 and CYP2B6 516G>T (P=0.001), time post dose (P=0.01) and BMI (P=0.07) to be independently associated with nevirapine plasma concentrations. CONCLUSION: Nevirapine is a substrate for ABCC10 and genetic variants influence its plasma concentrations. ABCC10 in lymphocytes and macrophages may also contribute to variability in intracellular permeation of nevirapine. Further studies are required to determine the clinical implications of these findings.

A pragmatic randomized controlled trial of thiopurine methyltransferase genotyping prior to azathioprine treatment: the TARGET study.

AIM: To conduct a pragmatic, randomized controlled trial to assess whether thiopurine methyltransferase (TPMT) genotyping prior to azathioprine reduces adverse drug reactions (ADRs). METHODS: A total of 333 participants were randomized 1:1 to undergo TPMT genotyping prior to azathioprine or to commence treatment without genotyping. RESULTS: There was no difference in the primary outcome of stopping azathioprine due to an adverse reaction (ADR, p = 0.59) between the two study arms. ADRs were more common in older patients (p = 0.01). There was no increase in stopping azathioprine due to ADRs in TPMT heterozygotes compared with wild-type individuals. The single individual with TPMT variant homozygosity experienced severe neutropenia. CONCLUSION: Our work supports the strong evidence that individuals with TPMT variant homozygosity are at high risk of severe neutropenia, whereas TPMT heterozygotes are not at increased risk of ADRs at standard doses of azathioprine.

The SLCO1B1 rs4149032 polymorphism is highly prevalent in South Africans and is associated with reduced rifampin concentrations: dosing implications.

Among patients with tuberculosis, rifampin plasma concentrations and sputum conversion rates have been reported to be lower in Africans. Rifampin is a substrate of P-glycoprotein (coded for by the ABCB1 gene) and organic anion-transporting polypeptide 1B1 (coded for by SLCO1B1). The objectives were to identify genetic polymorphisms of drug transporters and the transcriptional regulators pregnane X receptor (PXR) and constitutive androstane receptor (CAR) with an impact on rifampin pharmacokinetics in South Africans. Fifty-seven patients with tuberculosis from Cape Town underwent pharmacokinetic sampling during treatment with rifampin, pyrazinamide, isoniazid, and ethambutol. DNA was genotyped for ABCB1, SLCO1B1, PXR, and CAR polymorphisms by using real-time PCR. NONMEM was used for data analysis. The allele frequency of the SLCO1B1 rs4149032 polymorphism was 0.70. Patients heterozygous and homozygous for this polymorphism had reductions in the bioavailability (and, thus, the area under the curve [AUC]) of rifampin of 18% and 28%, respectively. Simulations showed that increasing the daily rifampin dose by 150 mg in patients with the polymorphism would result in plasma concentrations similar to those of wild-type individuals and reduce the percentage of patients with peak plasma concentrations (C(max)) below 8 mg/liter from 63% to 31%. ABCB1, PXR, and CAR polymorphisms were not associated with differences in rifampin pharmacokinetics. SLCO1B1 rs4149032 was present in most patients and was associated with substantially reduced rifampin exposure. These data suggest that the standard recommended dose of rifampin should be reconsidered for South Africans.

Genetic variants of ABCC10, a novel tenofovir transporter, are associated with kidney tubular dysfunction.

BACKGROUND: Tenofovir (TFV) causes kidney tubular dysfunction (KTD) in some patients, but the mechanism is poorly understood. Genetic variants in TFV transporters are implicated; we explored whether ABCC10 transports TFV and whether ABCC10 single-nucleotide polymorphisms (SNPs) are associated with KTD. METHODS: TFV accumulation was assessed in parental and ABCC10-transfected HEK293 cells (HEK293-ABCC10), CD4(+) cells and monocyte-derived macrophages (MDMs). Substrate specificity was confirmed by cepharanthine (ABCC10 inhibitor) and small interfering RNA (siRNA) studies. Fourteen SNPs in ABCC10 were genotyped in human immunodeficiency virus-positive patients with KTD (n = 19) or without KTD (controls; n = 96). SNP and haplotype analysis was performed using Haploview. RESULTS: TFV accumulation was significantly lower in HEK293-ABCC10 cell lines than in parental HEK293 cells (35% lower; P = .02); this was reversed by cepharanthine. siRNA knockdown of ABCC10 resulted in increased accumulation of TFV in CD4(+) cells (18%; P = .04) and MDMs (25%; P = .04). Two ABCC10 SNPs (rs9349256: odds ratio [OR], 2.3; P = .02; rs2125739, OR, 2.0; P = .05) and their haplotype (OR, 2.1; P = .05) were significantly associated with KTD. rs9349256 was associated with urine phosphorus wasting (P = .02) and ß2 microglobulinuria (P = .04). CONCLUSIONS: TFV is a substrate for ABCC10, and genetic variability within the ABCC10 gene may influence TFV renal tubular transport and contribute to the development of KTD. These results need to be replicated in other cohorts.

Exacerbation of hereditary warfarin resistance by azathioprine.

A 39-year-old Afro-Caribbean man with Crohn disease with recurrent deep vein thromboses and pulmonary emboli was commenced on lifelong warfarin treatment. The patient required high-dose warfarin (>140 mg/wk), which increased further during azathioprine treatment. Cessation of azathioprine resulted in an increase in the international normalized ratio (INR). Mutation analysis identified a Val66Met substitution in vitamin K epoxide reductase complex subunit 1 (VKORC1), consistent with severe warfarin resistance. This report is the first presentation where the patient had a defined hereditary resistance to warfarin, which was aggravated by concomitant azathioprine. It is important for clinicians to be aware of the interaction between warfarin and azathioprine, to monitor clinical response closely, and to manage the doses of both drugs accordingly.

Natural history of azathioprine-associated lymphopenia in inflammatory bowel disease patients: a prospective observational study.

INTRODUCTION: Azathioprine (AZA) is commonly used in inflammatory bowel disease (IBD) patients. Lymphopenia is a recognized effect of this treatment, but lymphopenia-related complications in IBD patients have not been widely reported. The incidence and progression of AZA-induced lymphopenia in IBD patients is not well described. There is no consensus on its optimal management in this group. AIMS AND METHODS: We assessed the incidence and progression of lymphopenia and its related complications in a cohort of IBD patients over a 14-month period in two large tertiary gastroenterology units. Analysis of prospectively collected data was performed. RESULTS: Fifty-two patients were studied prospectively with a median age of 34 years. Eighteen patients (34.6%) developed lymphopenia (<1.0×10(9)/l) during the course of treatment and 10 of them had severe lymphopenia (<0.6×10(9)/l). Lymphopenia lasted on average 85.4 days and spontaneously resolved in 13 patients. No lymphopenia related-complications were documented. Patients treated with steroids had a significantly higher rate of lymphopenia (83.3 vs. 44.1%, P=0.0083). CONCLUSION: Lymphopenia is common among IBD patients treated with AZA. However, it did not seem to be associated with a higher risk of opportunistic infections and spontaneously resolved in the majority of cases.

Adipogenic gene variants in patients with HIV-associated lipodystrophy.

OBJECTIVES: Although highly active antiretroviral therapy (HAART) has been hugely beneficial in the treatment of HIV, HIV lipodystrophy (HIVLD) associated with HAART is a serious adverse effect, with long-term consequences including metabolic disturbances and an increased risk of atherosclerotic disease. Although HIVLD is clearly related to the drug regimen, individual susceptibility also plays a role. We hypothesized that variation in genes regulating adipogenesis, and in those implicated in inherited forms of lipodystrophy, may predispose to the development of HIVLD. METHODS: DNA samples were obtained from 180 HAART-treatedHIV+ patients: 124 with HIVLD (HIVLD+) and 56 without HIVLD (HIVLD-). Diagnosis of HIVLD was carried out by clinician's confirmation of patient self-report. High-throughput genotyping using Sequenom was used to screen 62 single nucleotide polymorphisms (SNPs) in eight genes involved in adipogenesis and inherited forms of lipodystrophy. Statistical analysis was performed using Haploview. Multivariate analysis (logistic regression) was used to identify independent predictors of HIVLD development in HAART-treated patients. RESULTS: SNPs in two adipogenesis regulators, LPIN1 and CEBPα, showed a significant association with HIVLD whereas a SNP in ZMPSTE24, a zinc metalloproteinase involved in prelamin A processing, showed a trend toward significance. Multivariate analysis identified time since HIV diagnosis (P=0.001) and carriage of more than one associated allele (P=0.008) to be the most significant independent predictors for the development of HIVLD. CONCLUSION: Genetic variation in key regulators of adipogenesis could interfere with fat storage and metabolism contributing to the development of HIVLD in HAART-treated HIV patients. These results need replication in other cohorts.

Genetic analysis of thiopurine methyltransferase polymorphism in the Jordanian population.

UNLABELLED: This study provides the first analysis of the TPMT mutant allele frequency in a sample of the Jordanian population and indicates that TPMT*3A is the most common allele in Jordanian subjects. PURPOSE: thiopurine methyltransferase TPMT catalyses the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathiopurine. Thiopurine methyltransferase (TPMT) polymorphisms are the major determinants of interindividual differences in the severe haematological toxicity of 6-mercaptopurine. Several variants in the TPMT gene have been identified that correlate with a low activity phenotype. Four variant alleles, TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, are responsible for over 80% of the low or undetectable enzyme activity. The allelic frequency of TPMT variants has been established in many populations. METHODS: In this study, the frequencies of four (TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C) variants were investigated in 169 healthy Jordanian men (18-45 years of age). Single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom MassARRAY technology (Sequenom; San Diego, CA, USA). RESULTS: TPMT*3A and TPMT*3C were the only deficiency alleles detected in the Jordanian population with an allele frequency of 0.59% and 0.30% respectively. The TPMT*3A allele frequency is found to be lower than in the European Caucasian population. CONCLUSION: TPMT*3A and TPMT*3C were the only deficiency alleles detected in the Jordanian population with an allele frequency of 0.59% and 0.30% respectively. The TPMT*3A allele frequency is found to be lower than in the European Caucasian population.