Transethnic meta-analysis suggests genetic variation in the HEME pathway influences potassium response in patients treated with hydrochlorothiazide.

Hypokalemia is a recognized adverse effect of thiazide diuretic treatment. This phenomenon, which may impair insulin secretion, has been suggested to be a reason for the adverse effects on glucose metabolism associated with thiazide diuretic treatment of hypertension. However, the mechanisms underlying thiazide diuretic-induced hypokalemia are not well understood. In an effort to identify genes or genomic regions associated with potassium response to hydrochlorothiazide, without a priori knowledge of biologic effects, we performed a genome-wide association study and a multiethnic meta-analysis in 718 European- and African-American hypertensive participants from two different pharmacogenetic studies. Single-nucleotide polymorphisms rs10845697 (Bayes factor=5.560) on chromosome 12, near to the HEME binding protein 1 gene, and rs11135740 (Bayes factor=5.258) on chromosome 8, near to the Mitoferrin-1 gene, reached genome-wide association study significance (Bayes factor >5). These results, if replicated, suggest a novel mechanism involving effects of genes in the HEME pathway influencing hydrochlorothiazide-induced renal potassium loss.

Hydrochlorothiazide-induced hyperuricaemia in the pharmacogenomic evaluation of antihypertensive responses study.

OBJECTIVE: Elevations in uric acid (UA) and the associated hyperuricaemia are commonly observed secondary to treatment with thiazide diuretics. We sought to identify novel single nucleotide polymorphisms (SNPs) associated with hydrochlorothiazide (HCTZ)-induced elevations in UA and hyperuricaemia. METHODS: A genome-wide association study of HCTZ-induced changes in UA was performed in Caucasian and African American participants from the pharmacogenomic evaluation of antihypertensive responses (PEAR) study who were treated with HCTZ monotherapy. Suggestive SNPs were replicated in Caucasians and African Americans from the PEAR study who were treated with HCTZ add-on therapy. Replicated regions were followed up through expression and pathway analysis. RESULTS: Five unique gene regions were identified in African Americans (LUC7L2, ANKRD17/COX18, FTO, PADI4 and PARD3B), and one region was identified in Caucasians (GRIN3A). Increases in UA of up to 1.8 mg dL(-1) were observed following HCTZ therapy in individuals homozygous for risk alleles, with heterozygotes displaying an intermediate phenotype. Several risk alleles were also associated with an increased risk of HCTZ-induced clinical hyperuricaemia. A composite risk score, constructed in African Americans using the 'top' SNP from each gene region, was strongly associated with HCTZ-induced UA elevations (P = 1.79 × 10(-7) ) and explained 11% of the variability in UA response. Expression studies in RNA from whole blood revealed significant differences in expression of FTO by rs4784333 genotype. Pathway analysis showed putative connections between many of the genes identified through common microRNAs. CONCLUSION: Several novel gene regions were associated with HCTZ-induced UA elevations in African Americans (LUC7L2, COX18/ANKRD17, FTO, PADI4 and PARD3B), and one region was associated with these elevations in Caucasians (GRIN3A).

Genome-wide association analyses suggest NELL1 influences adverse metabolic response to HCTZ in African Americans.

Hydrochlorothiazide (HCTZ) is one of the most widely prescribed antihypertensive medications. Although it is well known that HCTZ is associated with hyperglycemia and hypertriglyceridemia, the mechanisms underlying these adverse effects are not well understood. We performed a genome-wide association study and meta-analysis of the change in fasting plasma glucose and triglycerides in response to HCTZ from two different clinical trials: the Pharmacogenomic Evaluation of Antihypertensive Responses and the Genetic Epidemiology of Responses to Antihypertensive studies. Two single-nucleotide polymorphisms (rs12279250 and rs4319515 (r(2)=0.73)), located at 11p15.1 in the NELL1 gene, achieved genome-wide significance for association with change in fasting plasma triglycerides in African Americans, whereby each variant allele was associated with a 28 mg dl(-1) increase in the change in triglycerides. NELL1 encodes a cytoplasmic protein that contains epidermal growth factor-like repeats and has been shown to represses adipogenic differentiation. These findings may represent a novel mechanism underlying HCTZ-induced adverse metabolic effects.

Association of chromosome 12 locus with antihypertensive response to hydrochlorothiazide may involve differential YEATS4 expression.

A recent genome-wide analysis discovered an association between a haplotype (from rs317689/rs315135/rs7297610) on Chromosome 12q15 and blood pressure response to hydrochlorothiazide (HCTZ) in African-Americans. Our aim was to replicate this association and investigate possible functional mechanisms. We observed similar associations between this haplotype and HCTZ response in an independent sample of 746 Caucasians and African-Americans randomized to HCTZ or atenolol treatment. The haplotype association was driven by variation at rs7297610, where C/C genotypes were associated with greater mean (systolic: 3.4 mmHg, P=0.0275; diastolic: 2.5 mmHg, P=0.0196) responses to HCTZ vs T-allele carriers. Such an association was absent in atenolol-treated participants, supporting this as HCTZ specific. Expression analyses in HCTZ-treated African-Americans showed differential pre-treatment leukocyte YEATS4 expression between rs7297610 genotype groups (P=0.024), and reduced post-treatment expression in C/C genotypes (P=0.009), but not in T-carriers. Our data confirm previous genome-wide findings at 12q15 and suggest differential YEATS4 expression could underpin rs7297610-associated HCTZ response variability, which may have future implications for guiding thiazide treatment.

Association of KCNJ1 variation with change in fasting glucose and new onset diabetes during HCTZ treatment.

Thiazide-induced potassium loss may contribute to new onset diabetes (NOD). KCNJ1 encodes a potassium channel and one study observed that a KCNJ1 single-nucleotide polymorphism (SNP) was associated with changes in fasting glucose (FG) during hydrochlorothiazide (HCTZ) treatment. We used linear regression to test association of KCNJ1 SNPs and haplotypes with FG changes during HCTZ treatment in the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) study. We used logistic regression to test association of KCNJ1 variation with NOD in HCTZ-treated patients from the International Verapamil SR Trandolapril Study (INVEST). Multivariate regression analyses were performed by race/ethnicity with false discovery rate (FDR) correction. In PEAR blacks, a KCNJ1 SNP was associated with increased FG during HCTZ treatment (beta=8.47, P(FDR)=0.009). KCNJ1 SNPs and haplotypes were associated with NOD risk in all INVEST race/ethnic groups (strongest association: odds ratio 2.14 (1.31-3.53), P(FDR)=0.03). Our findings support that KCNJ1 variation is associated with HCTZ-induced dysglycemia and NOD.

Melatonin Pathway and Atenolol-Related Glucose Dysregulation: Is There a Correlation?

Lower melatonin level, melatonin receptor gene variations, and atenolol treatment are associated with glucose dysregulation. We investigated whether atenolol-related glucose and melatonin changes are correlated, and whether single nucleotide polymorphisms (SNPs) in melatonin candidate genes contribute to interindividual variation in glucose change. Hypertensive Caucasians (n = 232) from the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) study treated with atenolol for 9 weeks were studied. Urinary 6-sulfatoxymelatonin (aMT6s) was measured pre- and posttreatment and normalized to urinary creatinine. Pharmacogenetic effects on glucose change of 160 SNPs in 16 melatonin candidate genes were assessed with multiple linear regression. Atenolol was associated with increased glucose (1.8 ± 10.1mg/dl, P = 0.02) and decreased aMT6s (-4.5 ± 10.1 ng/mg, P < 0.0001). However, the aMT6s change was not correlated with post-atenolol glucose change. SNP rs11649514 in PRKCB was associated with glucose change (P = 1.0×10(-4)). PRKCB is involved in the melatonin-insulin regulatory pathway, and may be important in mediating clinically meaningful atenolol-related hyperglycemia.

Effects of magnesium oxide on the lipid profile of healthy volunteers.

Elevated serum cholesterol is a risk factor in the development of coronary artery disease. Magnesium has been reported to decrease total serum cholesterol, low density lipoprotein, and very low density lipoprotein, and increase high density lipoprotein. A randomized, double-blind, placebo-controlled, crossover study was completed to determine if supplemented magnesium, in the form of magnesium oxide, would produce changes in the lipid profile. Fifty normal volunteers received placebo or magnesium oxide, 400 mg capsules, twice a day for 60 days, then switched to the alternate treatment. Weight, height, blood pressure, serum potassium, serum magnesium, and a lipid profile were determined initially and after each treatment. Analysis of variance (ANOVA), comparing the mean of each component of the lipid profile at baseline and after each treatment, showed no significant difference. In conclusion, supplemental magnesium oxide did not produce statistically significant changes in the lipid profile in this group of healthy volunteers.

Outcome analysis of a pharmacist-managed anticoagulation service.

The primary objective of this study was to determine if a pharmacist-managed anticoagulation monitoring service (AMS) improved the outcomes of patients receiving warfarin in a family practice setting and was cost effective in treating and preventing thromboembolic disorders. A retrospective chart review was performed on all patients at the University of Florida's Family Practice Residency Program who received warfarin pharmacotherapy between October 1, 1988, and December 15, 1993. The outcomes of patients followed by AMS were compared with those of a control group consisting of patients receiving warfarin but followed only by their physician. Outcomes were evaluated based on the number of thromboembolic and hemorrhagic events, as well as unplanned clinic visits, emergency room visits, and hospital admissions. Cost of hospital admissions, emergency room visits, and participation in the AMS were analyzed. During 28 person-years of treatment, control subjects sustained 12 thromboembolic events (2 pulmonary embolisms, 1 cerebrovascular accident, and 9 deep venous thromboses) and 2 minor and 5 major hemorrhagic events. The study group reported two minor hemorrhagic events during a total of 60 person-years. The control group was 20 times more likely than the study group to experience any event (rate ratio 20, 95% CI 5-87). In addition, hospitalization and emergency room charges indicated an actual cost of $119,074.95 for the control group's events. The cost to this group for 28 person-years of participation in the AMS would have been $5040.00. A potential cost avoidance of $4072.68 per person-year of follow-up may have been possible if these patients had been followed by the AMS. A pharmacist-managed AMS in a family practice setting can result in improved outcomes for patients receiving warfarin and is cost effective.

A randomized, prospective study measuring outcomes after antibiotic therapy intervention by a multidisciplinary consult team.

Our aim was to identify financial and outcome benefits of therapeutic intervention by a multidisciplinary antimicrobial treatment team composed of pharmacists, a clinical microbiologist, and an infectious disease specialist. Of 252 consecutive inpatients receiving suboptimal intravenous antibiotics identified by the clinical pharmacist, 127 were prospectively randomized to intervention and 125 to a control group. The groups were similar with regard to severity of illness, infection type, and time from admission to randomization. Physicians received timely, detailed reviews of relevant microbiologic and clinical data with recommendations of possible optimal antibiotic choices, dosages, and rationales. Median length of stay after randomization for control and intervention groups was 9.0 days and 5.7 days, respectively (3.3-day difference, p=0.0001). Fifteen (12.0%) and eight patients (6.3%), respectively, died, although the time-specific mortality risk was not significantly different when length of postrandomization follow-up and time to death were taken into account. Physician acceptance of suggestions was 89%. Median patient charges for radiology, laboratory, pharmacy, and room were reduced by $4404/intervention, and median hospital costs were reduced by $2642/intervention. A multidisciplinary antimicrobial therapy team can be a useful information source for physicians, improve outcomes in hospitalized patients receiving intravenous antimicrobials, and result in substantial cost savings.

Management of essential hypertension.

Hypertension, in spite of a very high prevalence, remains undertreated. This is not due to a lack of effective therapeutic modalities. Non-pharmacological treatments can be effective in many patients. If those treatments fail to reduce blood pressure sufficiently, the physician can choose between numerous classes of antihypertensive agents. However, interpatient variability in response to these agents is high, and use of multiple agents is frequently necessary. Thus, no single class has proven to be superior for the majority of patients. This article will review the different non-pharmacological and pharmacological methods available to treat hypertension, as well as the guidelines that are available to aid in proper selection of a treatment regimen.

Tuberculosis. The primary care physician's role in eradication.

The resurgence of tuberculosis in the United States presents a challenge for primary care physicians. The disease remains concentrated in the growing population of socioeconomically disadvantaged persons, immigrants from areas where drug resistance is common, certain racial groups, persons in extended-care facilities, alcohol and drug abusers, and persons infected with the human immunodeficiency virus. Because people in these groups are much less likely than others to seek regular medical care, it is difficult to identify and treat active tuberculosis in these populations. Contacts of patients with tuberculosis are equally difficult to identify. Active intervention by primary care physicians--including tuberculin screening, prophylactic therapy, treatment of active disease, and follow-up--is needed to help achieve the goal of eradicating tuberculosis.

Infectious vaginitis. Selecting therapy and preventing recurrence.

Vaginal candidiasis, trichomoniasis, and bacterial vaginosis can be difficult to manage because of predisposing factors and frequent recurrence. Thus, in addition to drug therapy, management should include attempts to minimize factors that contribute to recurrence. Both topical and oral agents are available for vaginal candidiasis and bacterial vaginosis, and both routes of administration appear equally safe and effective. Topical therapy may be used for these conditions in pregnant women. Only oral therapy is optimal for trichomoniasis. However, during pregnancy, the infection may be managed with topical clotrimazole. Currently, treatment of a woman's sexual partner is recommended in the management of trichomoniasis and is optional in cases of bacterial vaginosis. Sexual activity may also contribute to the recurrence of vaginal candidiasis; however, more studies are needed to evaluate the impact on recurrence rates of treating the male partner.

Newer antihypertensive agents.

Three recent additions to the list of antihypertensive agents have been approved for use as monotherapy or in combination with other drugs. Betaxolol hydrochloride (Kerlone) maintains its effect for 24 hours, making it a true once-a-day beta blocker. Penbutolol sulfate (Levatol) is as effective as other beta blockers and diuretics. Doxazosin mesylate (Cardura), a selective alpha 1 blocker, also allows once-a-day dosing and has produced favorable changes in lipid profiles. Two new drug delivery systems, one for verapamil hydrochloride (Verelan) and one for extended-release nifedipine (Procardia XL), allow less frequent dosing and may offer other advantages, such as greater compliance and a more tolerable side-effect profile.

The new antimicrobial agents. When they're the best choice and when they're not.

The number of antibiotics available to the clinician for treatment of infectious diseases continues to increase. However, choosing an agent just because it is new is not always cost-effective and may encourage the development of bacterial resistance. The site of infection, pharmacokinetic data, minimum inhibitory concentration, and cost must all be considered in selecting the optimal antimicrobial agent for a particular clinical situation.

Impact of CYP2D6 polymorphisms on clinical efficacy and tolerability of metoprolol tartrate.

Metoprolol is a selective ß-1 adrenergic receptor blocker that undergoes extensive metabolism by the polymorphic enzyme cytochrome P450 2D6 (CYP2D6). Our objective was to investigate the influence of CYP2D6 polymorphisms on the efficacy and tolerability of metoprolol tartrate. Two hundred and eighty-one participants with uncomplicated hypertension received 50 mg of metoprolol twice daily followed by response-guided titration to 100 mg twice daily. Phenotypes were assigned based on results of CYP2D6 genotyping and copy number variation assays. Clinical response to metoprolol and adverse effect rates were analyzed in relation to CYP2D6 phenotypes using appropriate statistical tests. Heart rate response differed significantly by CYP2D6 phenotype (P < 0.0001), with poor and intermediate metabolizers showing greater reduction. However, blood pressure response and adverse effect rates were not significantly different by CYP2D6 phenotype. Other than a significant difference in heart rate response, CYP2D6 polymorphisms were not determinants of variability in metoprolol response or tolerability.

Hydrochlorothiazide and atenolol combination antihypertensive therapy: effects of drug initiation order.

For combination antihypertensive therapy with thiazide diuretics and beta-blockers, the effect of the order of initiation of the drugs on the outcome has not been tested. Patients with uncomplicated hypertension were randomized to receive either hydrochlorothiazide (HCTZ) or atenolol monotherapy, followed by addition of the alternative drug. Blood pressure (BP) responses were evaluated by race and order of drug initiation. A total of 368 participants received combination therapy. Among the participants, blacks showed a greater BP-lowering effect than whites did with HCTZ monotherapy (-13.0/-7.4 mm Hg vs. -8.0/-4.2 mm Hg, P < 0.001) but a smaller BP-lowering effect than did whites with atenolol monotherapy (-1.1/-2.9 mm Hg vs. -9.9/-9.2 mm Hg, P < 0.0001). These differences were not evident during combination therapy. However, both groups showed greater response to HCTZ + atenolol than to atenolol + HCTZ (-19.1/-14.2 mm Hg vs. -15.6/-11.3 mm Hg, P < 0.0001). Despite optimal dosing of HCTZ + atenolol, only two-thirds of the participants achieved BP control. In HCTZ/atenolol combination antihypertensive therapy, the order in which the drugs are initiated affects total BP lowering during the first 4-6 months of therapy.

Recent advances: ambulatory care and family medicine.

Recent advances in primary care have been and continue to be exciting and innovative. The evolution of pharmaceutical care has the potential to have an immediate impact in the primary care arena. A major focus of primary care research will center on the evaluation of pharmaceutical care and the consequences of implementing pharmaceutical care, such as reimbursement for clinical services, quality of life, and improved clinical outcomes. With an increasing emphasis being placed on the provision of health care through primary care providers, advances in primary care/family medicine pharmacotherapy promise to remain exciting and innovative.

Clinical significance of magnesium: a review.

With the increased concern surrounding diuretic-induced electrolyte losses, numerous articles have surfaced investigating the detrimental effects of diuretic-induced hypomagnesemia. This article's purpose is to familiarize the reader with hypomagnesemia and hypermagnesemia. Methods of detection, symptoms, etiologies, and potential modes of therapy are discussed. Particular attention is given to the role magnesium plays in the cardiovascular system with additional discussion on lipid alterations and glucose handling. Specific suggestions are given for the inpatient and outpatient treatment of hypomagnesemia.