Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002962 (angina)
 21,142 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The calcium channel blocker verapamil[2,8-bis-(3,4-dimethoxyphenyl)-6-methyl-2-isopropyl-6- azaoctanitrile] is widely used in the treatment of hypertension, angina pectoris and cardiac arrhythmias. The drug undergoes extensive and variable hepatic metabolism in man with the major metabolic steps comprising formation of D-617 [2-(3,4-dimethoxyphenyl)-5-methylamino-2-isopropylvaleronitrile] and norverapamil [2,8-bis-(3,4-dimethoxyphenyl)-2-isopropyl-6-azaoctanitrile]. The enzymes involved in metabolism of verapamil have not been characterized so far. Identification of these enzymes would enable estimation of both interindividual variability in verapamil metabolism introduced by the respective pathway and potential for metabolic interactions. We therefore characterized the enzymes involved in formation of D-617 and norverapamil. The maximum rate of formation of D-617 and norverapamil was determined in the microsomal fraction of 21 human livers which had been previously characterized for the individual expression of various P450 enzymes (CYP1A2, CYP2C, CYP2D6, CYP2E1 and CYP3A3/4) by means of Western blotting. Specific antibodies directed against CYP3A were used to inhibit formation of D-617 and norverapamil. Finally, formation of both metabolites was investigated in microsomes obtained from yeast cells which were genetically engineered for stable expression of human P450. Formation of D-617 was correlated with the expression of CYP3A (r = 0.85; P < 0.001) and CYP1A2 (r = 0.57; P < 0.01) in the microsomal fraction of 21 human livers after incubation with racemic verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of P450 enzymes involved in metabolism of verapamil in humans. 823 10

Ranolazine is a compound that is approved by the US FDA for the treatment of chronic angina pectoris in combination with amlodipine, beta-adrenoceptor antagonists or nitrates, in patients who have not achieved an adequate response with other anti-anginals. The anti-anginal effect of ranolazine does not depend on changes in heart rate or blood pressure. It acts through different pharmacological mechanisms where inhibition of the late inward sodium current (reducing calcium overload and thereby left ventricular diastolic tension) is one plausible mechanism of reduced oxygen consumption. Initial studies used an oral solution or an immediate-release (IR) capsule, but subsequently an extended-release (ER) formulation was developed to allow for twice-daily administration with maintained efficacy. Following administration of an oral solution or IR capsule, peak plasma concentrations (C(max)) are observed within 1 hour. After administration of radiolabelled ranolazine, 73% of the dose was excreted in urine, and unchanged ranolazine accounted for <5% of radioactivity in both urine and faeces. The absolute bioavailability ranges from 35% to 50%. Food has no effect on rate or extent of absorption from the ER formulation. Ranolazine protein binding is about 61-64% over the therapeutic concentration range. Volume of distribution at steady state ranges from 85 to 180 L. Ranolazine is extensively metabolised by cytochrome P450 (CYP) 3A enzymes and, to a lesser extent, by CYP2D6, with approximately 5% excreted renally unchanged. Elimination half-life of ranolazine is 1.4-1.9 hours but is apparently prolonged, on average, to 7 hours for the ER formulation as a result of extended absorption (flip-flop kinetics). Elimination occurs through parallel linear and saturable elimination pathways, where the saturable pathway is related to CYP2D6, which is partly inhibited by ranolazine. Oral plasma clearance diminishes with dose from, on average, 45 L/h at 500 mg twice daily to 33 L/h at 1000 mg twice daily. The departure from dose proportionality for this dose range is modest, with increases in steady-state C(max) and area under plasma concentration-time curve (AUC) from 0 to 12 hours of 2.5- and 2.7-fold, respectively. Ranolazine pharmacokinetics are unaffected by sex, congestive heart failure and diabetes mellitus. AUC increases up to 2-fold with advancing degree of renal impairment. Ranolazine is a weak inhibitor of CYP3A, and increases AUC and C(max) for simvastatin, its metabolites and HMG-CoA reductase inhibitor activity <2-fold. Digoxin AUC is increased 40-60% by ranolazine through P-glycoprotein inhibition. Ranolazine AUC is increased by CYP3A inhibitors ranging from 1.5-fold for diltiazem 180 mg once daily to 3.9-fold for ketoconazole 200 mg twice daily. Verapamil increases ranolazine exposure approximately 2-fold. CYP2D6 inhibition has a negligible effect on ranolazine exposure.
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PMID:Clinical pharmacokinetics of ranolazine. 1664 Apr 53

Study aim was to investigate the association of lipoprotein (a) [Lp(a)] level with the development of cardiovascular complications in long-term follow-up period after coronary artery bypass grafting (CABG). Patients with chronic ischemic heart disease (IHD) (n = 361, 88% men, mean age 55 +/- 9 years) who had had CABG were included in the study. Before surgery we assessed presence of classical risk factors, left ventricular ejection fraction, concentrations of lipids and Lp(a) in blood serum. During follow-up (from 1 to 140, mean 66 +/- 34 months) we registered cardiac deaths, nonfatal myocardial infarctions (MI), strokes, repeat procedures of revascularization, and hospitalizations due to relapse or progression of angina pectoris. Information on prognosis was obtained from 263 patients. In 109 of them we registered 142 serious events including cardiac death n = 20 (14%), nonfatal MI n = 14 (10%), myocardial revascularization (n = 35), 29 (20%) with stenting), repeat CABG n = 6 (4%), hospitalization due to angina pectoris n = 53 (37%), stroke n = 4 (3%), noncardiac outcome n = 16 (10%). In subjects with hyperlipidemia (a) [HLp(a) - Lp(a) > 30 mg/l] survival after CABG was lower (log rank p < 0.001): 11 of 93 (11.3%) and 9 of 170 (5.2%) patients died among those with Lp(a) > 30 and < 30 mg/I, respectively. Relative risk (RR) of any cardiovascular complication was 3.24 (95% confidence interval [CI] 2.18 to 4.83, p < 0.001), of death - 2.89 (95% CI 1.31 to 6.35, p < 0.01), and of MI A 1.01 (95% CI 1.00 to 1.02; p = 0.02). RR of development of MI and cardiac death in patients with HLp(a) in 5 years was 2.61 (95% CI 1.11 to 5.74; p = 0.02), in 10 years - 2.95 (95% CI 1.50 to 5.79; p < 0.001). In patients with chronic IHD high level of Lp(a) can serve as independent predictor of unfavorable events including death and nonfatal MI during 10 years after CABG.
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PMID:[High level of lipoprotein (a) as a predictor of poor long-term prognosis after coronary artery bypass surgery]. 2162 97

Purpose. The case of a kidney transplant recipient who experienced a probable drug interaction between sirolimus and ranolazine is reported. Summary. The narrow therapeutic window of immunosuppressive therapy in transplant recipients requires close monitoring for potential drug-drug interactions. The patient, a 57-year-old Caucasian male kidney transplant recipient, was stable for years on sirolimus as his primary immunosuppressive agent and had a history of chronic angina, for which he was prescribed ranolazine. Upon addition and dose escalation of ranolazine, whole blood sirolimus levels more than tripled, rising to immeasurably high concentrations. After holding sirolimus on multiple occasions and reducing dosage more than 50%, blood levels returned to therapeutic range, while continuing ranolazine. Conclusion. Since ranolazine is a documented P-GP and CYP3A inhibitor, and sirolimus a known substrate for both pathways, it is proposed that ranolazine inhibition of P-GP and CYP3A4 contributed to the significant elevation in sirolimus exposure. No alternative causes for the rise in sirolimus exposure were found, and assessment with the Drug Interaction Probability Scale finds this interaction to be probable. Clinicians should be aware of the potential for this interaction to cause elevated sirolimus exposure and subsequent increase in clinical effect or toxicity, in this case overimmunosuppression.
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PMID:Drug Interaction between Sirolimus and Ranolazine in a Kidney Transplant Patient. 2457 9