Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been proposed that excessive intrarenal conversion of cortisol to 6 beta-hydroxycortisol by CYP3A may mediate increased tubular reabsorption of sodium, leading to a state of mild volume expansion and the clinical phenotype of salt-sensitive hypertension. Therefore, we characterized CYP3A activity in a bank of microsomes from human kidneys using the formation of 1'-hydroxymidazolam (1'-OHM) as a prototypical CYP3A-catalyzed reaction. Maximal rates of metabolite formation occurred at midazolam concentrations of 12.5-50 microM; higher concentrations resulted in dramatic substrate inhibition. At 12.5 microM midazolam, 4 of 27 kidneys exhibited relatively high mean +/- standard deviation 1'-OHM formation rate (184.0 +/- 14.4 pmol/hr/mg) compared with the remaining 23 samples, which had a mean formation rate of (10.1 +/- 6.4 pmol/hr/mg). Triacetyloleandomycin and anti-CYP3A antibody inhibited midazolam hydroxylation by 53% and 57%, respectively. The correlation between CYP3A5 content, determined through immunoblotting, and 1'-OHM formation rate was high (r2 = 0.84, 24 experiments). The expressions of mRNA corresponding to CYP3A3, CYP3A4, CYP3A5, and CYP3A7 were determined through polymerase chain reaction with specific oligonucleotides as primers. All kidneys examined (25 experiments) expressed CYP3A5 protein and contained the corresponding CYP3A5 mRNA. CYP3A4 mRNA was detected in 40% of the kidney samples, and 70% of those that contained detectable CYP3A4 mRNA also expressed detectable levels of the corresponding protein. Therefore, in contrast to hepatic tissue, in which CYP3A4 is universally expressed, CYP3A5 is the ubiquitously expressed member of the CYP3A family in renal tissue. The distribution of enzyme activity and protein content suggests bimodality and may represent induction of CYP3A5 in a select population and/or a genetically determined organ-specific pattern of expression.
 ...
PMID:Bimodal distribution of renal cytochrome P450 3A activity in humans. 870 Jan 18

Mibefradil, a tetralol derivative, is a new long-acting calcium antagonist used for the treatment of patients with hypertension and chronic stable angina pectoris. The drug is virtually completely metabolised, with less than 3% of an oral dose excreted unchanged in urine. Its metabolism occurs via parallel pathways, which fall into 2 broad categories: esterase-catalysed hydrolysis (producing the major plasma metabolite) and cytochrome P450 (CYP) 3A4-mediated oxidation. Plasma protein binding is greater than 99.5%, predominantly to alpha 1-acid glycoprotein. Oral multiple dose administration of mibefradil 50 or 100 mg once daily is associated with inhibition of the CYP3A4 pathway of metabolism, increasing the half-life and bioavailability of the parent compound. The intensity of the inhibition of CYP similarly results in numerous clinically relevant drug interactions which ultimately motivated the voluntary withdrawal of mibefradil from the market. With multiple oral doses of 50 to 100 mg once daily, the time to maximum plasma concentration was approximately 2.4 hours, absolute bioavailability was around 80%, clearance was 5.7 to 7.5 L/h, oral terminal exponential volume of distribution was 180 L, and terminal exponential half-life was 22 hours (ranging between 17 and 25 hours). A NONMEM sparse data analysis indicated that apparent clearance is not affected by race, gender, age or bodyweight. Renal function does not affect the pharmacokinetics of mibefradil.
 ...
PMID:Clinical pharmacokinetics of mibefradil. 988 14

Pharmacological interaction is identified among other aspects when the effects of a drug are significantly altered clinically by the presence of food. The most important clinical significance in the history of drug-food interactions occurred in the fifties, the vitamin B6 deficiency when administering the tuberculostatic isoniazide, but there is no doubt that the interaction in the sixties between drugs that were inhibitors of the enzyme mono-amine oxidase and the biogenic amines tyramine and histamine had an important clinical significance due to the increase in hypertension and deaths due to cerebro-vascular accidents. In the seventies the types of interactions were due to the chelation between tetracyclines and the calcium of milk products, influencing the bioavailability of the antibiotic, and from this point on, studies explore in depth the interaction of foods with the different steps in the pharmacokinetics of the drugs (absorption, distribution, metabolization, and excretion), and these have helped to explain the metabolization interactions of drugs like the clinical significance between grapefruit juice whose naringenine flavonoid is a powerful inhibitor of cytochrome 450, particularly the CYP3A4 family, and terfenadine (antihistamine), with an increase in the plasma levels of the drug and patient death due to ventricular arrhythmia. In the USA the Joint Commission on Accreditation of Health Care Organization (JCAHO) has recommended monitoring of the possible drug and food interactions since 1985, and recommends that patients be informed of this. Despite the recommendations of the JCAHO, few American hospitals have protocolized these interactions and even fewer comply with these, and according to some authors, this is due to the lack of motivation caused by the lack of clinical significance. In this chapter we will study the effect of foods on drugs in two aspects: at the pharamcokinetic level with the possible alterations in absorption, distribution, metabolization, and excretion, and at the pharamcodynamic level, by alterations in the action of the drug. Also, based on a study by Delgado, which we have changed somewhat, we will report how the drugs should be taken to avoid interactions with foods. As a conclusion, it is difficult to establish which are the relevant drug-food interactions, unless they have given clinical problems. The following are important: a) drugs with a narrow therapeutic margin in which an absorption problem or a metabolization problem may disrupt the plasma levels and the patient needs (digoxin, teophylline, cyclosporin, etc). And b) the drugs like some antibiotics that, because of their action mechanisms, need to maintain adequate plasma concentrations.
 ...
PMID:[Drug-food interactions]. 1054 35

Erythromycin breath tests (ERBT) were performed to determine age and racial effects on CYP3A4-mediated hepatic clearance in hypertensive men (n = 43) in the clinical setting. Older hypertensive African American men (n = 19: 71 +/- 8 years, mean +/- SD) had faster ERBT clearance compared with Caucasian (n = 20: 72 +/- 6 years) hypertensive men (at 20 minutes after dosing: 0.042 +/- 0.01 percent dose/min exhaled vs. 0.033 +/- 0.013; at 60 minutes after dosing: 0.030 +/- 0.05 vs. 0.023 +/- 0.007 percent dose/min exhaled; ANOVA, p = 0.007), while age, smoking, and reported alcohol intake did not affect ERBT. The data suggest faster hepatic CYP3A-mediated clearance in African American men compared with Caucasian men, and that race may significantly affect CYP3A-mediated hepatic clearance in patients treated for hypertension.
 ...
PMID:Race but not age affects erythromycin breath test results in older hypertensive men. 1126 73

Irbesartan is an angiotensin II receptor antagonist indicated for the treatment of patients with hypertension. Although irbesartan does not require biotransformation for its pharmacological activity, it does undergo metabolism via the cytochrome P450 (CYP) 2C9 isoenzyme and negligible metabolism by the CYP3A4 isoenzyme. The long term treatment of patients with hypertension is generally required for effective management of the disease, and the use of concurrent medications is usually inevitable. This paper reviews the drug and food interaction trials involving irbesartan that have been conducted to date. Based on the available literature, no significant interactions have been identified between irbesartan and hydrochlorothiazide, nifedipine, simvastatin, tolbutamide, warfarin, magnesium and aluminum hydroxides, digoxin or food. Fluconazole did increase the steady-state peak plasma concentration (by 19%) and area under the concentration-time curve (by 63%) of irbesartan, but these increases are not likely to be clinically significant. In summary, irbesartan has demonstrated minimal potential for drug or food interactions in trials conducted to date.
 ...
PMID:Drug interactions with irbesartan. 1152 26

With the aging of the population, death from coronary heart disease (CHD) and stroke has become more prevalent. Cardiovascular disease (CVD) risk factors, such as hypertension, obesity, and diabetes mellitus increase with age as well. Recent secondary-prevention studies have established the positive effect of statins in decreasing the risk of CHD mortality through the lowering of cholesterol. Statins have an excellent safety record, at least with users under age 65, and provide a cheaper alternative to more costly medical options. The most serious side effect associated with their use is myopathy, which is infrequent. Drug interactions have been found with drugs that compete for the same CYP450 isoenzymes as statins. Several drugs have been shown to significantly inhibit the CYP3A4 pathway; in combination with statins such as lovastatin, simvastatin, atorvastatin, and cerivastatin, they have been shown to elevate serum concentrations of these statins, or may increase the risk of myopathy. Alternatively, other drugs can inhibit the CYP2C9 pathway and may elevate serum concentration of fluvastatin. Due to the number of medications the elderly receive, an understanding of the various metabolic pathways is of vital importance to minimize the potential for drug interactions. The elderly population, while at high risk for CVD, is currently undertreated. Statins can effectively lower low-density lipoprotein cholesterol levels and lessen the risk of CVD for this population.
 ...
PMID:Treatment of the elderly with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors: focus on drug interactions. 1158 28

Citalopram is a chiral antidepressant drug. Its eutomer, S-citalopram (escitalopram), has recently been introduced as an antidepressant. In an open pilot study, four outpatients and two inpatients with a major depressive episode (ICD-10), and who were nonresponders to a 4-week pretreatment with 40-60 mg/day citalopram, were comedicated for another 4-week period with carbamazepine (200-400 mg/day). Some of the patients suffered also from comorbidities: Phobic anxiety disorder with panic attacks (n=2), generalised anxiety disorder, alcohol abuse, dependent personality disorder, hypertension (n=1). After a 4-week augmentation therapy with carbamazepine, a significant (P<0.03) decrease of the plasma concentrations of S-citalopram and R-citalopram, by 27 and 31%, respectively, was observed. Apparently, the probable induction of CYP3A4 by carbamazepine results in a nonstereoselective increase in N-demethylation of citalopram. Moreover, there was a significant (P<0.03) decrease of the ratio S/R-citalopram propionic acid derivative, the formation of it being partly regulated by MAO-A and MAO-B. Already, within 1 week after addition of carbamazepine, there was a slight but significant (P<0.03) decrease of the MADRS depression scores, from 27.0+/-7.7 (mean+/-S.D.) to 23.3+/-6.6, and the final score on day 56 was 18.8+/-10.9. The treatment was generally well tolerated. There was no evidence of occurrence of a serotonin syndrome. After augmentation with carbamazepine, treatment related adverse events were: Nausea in one case, diarrhea in one case, and rash in two cases. In conclusion, the results of this pilot study suggest that carbamazepine augmentation of a citalopram treatment in previous nonresponders to citalopram may be clinically useful, but that in addition carbamazepine can lead to a decrease of the plasma concentrations of the active enantiomer escitalopram.
 ...
PMID:Carbamazepine augmentation in depressive patients non-responding to citalopram: a pharmacokinetic and clinical pilot study. 1200 77

Treatment of HIV infection with potent combination antiretroviral therapy has resulted in major improvement in overall survival, immune function and the incidence of opportunistic infections. However, HIV infection and treatment has been associated with the development of metabolic complications, including hyperlipidaemia, diabetes mellitus, hypertension, lipodystrophy and osteopenia. Safe pharmacological treatment of these complications requires an understanding of the drug-drug interactions between antiretroviral drugs and the drugs used in the treatment of metabolic complications. Since formal studies of most of these interactions have not been performed, predictions must be based on our understanding of the metabolism of these agents. All HIV protease inhibitors are metabolised by and inhibit cytochrome P450 (CYP) 3A4. Ritonavir is the most potent inhibitor of CYP3A4. Ritonavir and nelfinavir also induce a host of CYP isoforms as well as some conjugating enzymes. The non-nucleoside reverse transcriptase inhibitor delavirdine potently inhibits CYP3A4, whereas nevirapine and efavirenz are inducers of CYP3A4. Drug interaction studies have been performed with HIV protease inhibitors and HMG-CoA reductase inhibitors. Coadministration of ritonavir plus saquinavir to HIV-seronegative volunteers resulted in increased exposure to simvastatin acid by 3059%. Atorvastatin exposure increased by 347%, but exposure to active atorvastatin increased by only 79%. Conversely, pravastatin exposure decreased by 50%. Similar results have been obtained with combinations of simvastatin and atorvastatin with other HIV protease inhibitors. Thus, the lactone prodrugs simvastatin and lovastatin should not be used with HIV protease inhibitors. Atorvastatin may be used with caution. Although there are no formal studies available, calcium channel antagonists and repaglinide may have significant interactions and toxicity when used with HIV protease inhibitors because of their metabolism by CYP3A4. Sulfonylurea drugs utilise mainly CYP2C9 for metabolism, and this isoenzyme may be induced by ritonavir and nelfinavir with a resulting decrease in efficacy of the sulfonylurea. Losartan may have increased effect when coadministered with ritonavir and nelfinavir because of the induction of CYP2C9 and the expected increase in formation of the active metabolite, E-3174. Overall, well-designed drug-drug interaction studies at steady state are needed to determine whether antiretroviral drugs may be safely coadministered with many of the drugs used in the treatment of the metabolic complications of HIV infection.
 ...
PMID:Interactions between antiretroviral drugs and drugs used for the therapy of the metabolic complications encountered during HIV infection. 1240 66

(1) Sirolimus, an immunosuppressant, is chemically related to tacrolimus but has a different mechanism of action. (2) In a double-blind trial in patients also treated with ciclosporin and a steroid, sirolimus was more effective than azathioprine at preventing acute rejection during the first three months, but caused more adverse effects (especially renal). (3) An unblinded trial compared ciclosporin + steroid + sirolimus with steroid + sirolimus for maintenance treatment. Ciclosporin was withdrawn gradually from the steroid + sirolimus group. Side effects from ciclosporin were therefore reduced (mainly nephrotoxicity and arterial hypertension), but rates of acute rejection, hepatotoxicity, and thrombocytopenia went up. (4) Sirolimus has numerous adverse effects, including hyperlipidemia, thrombocytopenia, hepatic disorders and opportunistic infections. The adverse effects of long term treatment are unknown. Sirolimus is metabolised by the cytochrome P450 isoenzyme CYP3A4, so may induce drug interactions. (5) In practice, sirolimus offers no advantage over existing immunosuppressive treatments for people with renal transplants.
 ...
PMID:Sirolimus: new preparation. No tangible advance in renal transplantation. 1246 93

The purpose of this study is to test the hypothesis that the inhibitory effects of estradiol in human coronary vascular smooth muscle cells are mediated via local conversion to methoxyestradiols via specific cytochrome P450s (CYP450s) and catechol-O-methyltransferase (COMT). The inhibitory effects of estradiol on serum-induced cell activity (DNA synthesis, cell number, collagen synthesis, and cell migration) were enhanced by 3-methylcholantherene, phenobarbital (broad-spectrum CYP450 inducers), and beta-naphthoflavone (CYP1A1/1A2 inducer) and were blocked by 1-aminobenzotriazole (broad-spectrum CYP450 inhibitor). Ellipticine, alpha-naphthoflavone (selective CYP1A1 inhibitors), and pyrene (selective CYP1B1 inhibitor), but not ketoconazole (selective CYP3A4 inhibitor) or furafylline (selective CYP1A2 inhibitor), abrogated the inhibitor effects of estradiol on cell activity, a profile consistent with a CYP1A1/CYP1B1-mediated mechanism. The inhibitory effects of estradiol were blocked by the COMT inhibitors OR486 and quercetin. The estrogen receptor antagonist ICI 182,780 blocked the inhibitory effects of estradiol, but only at concentrations that also blocked the metabolism of estradiol to hydroxyestradiols (precursors of methoxyestradiols). Western blot analysis revealed that coronary smooth muscle cells expressed CYP1A1 and CYP1B1. Moreover, these cells metabolized estradiol to hydroxyestradiols and methoxyestradiols, and the conversion of 2-hydroxyestradiol to 2-methoxyestradiol was blocked by OR486 and quercetin. These findings provide evidence that the inhibitory effects of estradiol on coronary smooth muscle cells are largely mediated via CYP1A1- and CYP1B1-derived hydroxyestradiols that are converted to methoxyestradiols by COMT.
Hypertension 2003 Mar
PMID:CYP450- and COMT-derived estradiol metabolites inhibit activity of human coronary artery SMCs. 1262


1 2 3 4 5 6 7 8 9 Next >>