Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344232 (blurred vision)
 2,072 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The three best-described genetic polymorphisms of drug metabolism--the debrisoquin/sparteine type of oxidative polymorphism (hereafter referred to as the debrisoquin polymorphism), the polymorphism of N-acetylation, and the mephenytoin type of oxidative polymorphism--are reviewed. For all three polymorphisms, the poor-metabolizer phenotype is inherited as an autosomal recessive trait. The debrisoquin and mephenytoin oxidative polymorphisms involve defects in two separate cytochrome P450 enzymes. The prevalence of the poor-metabolizer phenotype for debrisoquin ranges between 2% and 10% for groups of various ethnic origins. The poor-metabolizer phenotype for mephenytoin comprises about 5% of the Caucasian population and about 20% of the Japanese population. N-acetyltransferase is a cytosolic enzyme whose clinical polymorphism was discovered using isoniazid as the substrate probe. The prevalence of the slow-acetylator phenotype among American and European Caucasian and American black groups is about 50%; among the Japanese it is about 10%. More than 20 agents are substrates for debrisoquin hydroxylase, about 15 for N-acetyltransferase, and 3-5 for mephenytoin. In poor metabolizers, debrisoquin can cause hypotension, and sparteine can cause blurred vision, headache, and dizziness. Clinical consequences of the slow-acetylator phenotype include increased susceptibility to systemic lupus erythematosus induced by procainamide and hydralazine, peripheral neuropathy induced by isoniazid, hydralazine, and dapsone, and sulfasalazine-induced dose-related leukopenia, nausea, vomiting, headache, and vertigo. After administration of mephenytoin, poor metabolizers have increased somnolence and intellectual impairment. Awareness of genetic polymorphisms of drug metabolism should improve understanding of interindividual variability in drug disposition and response.
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PMID:Polymorphic drug metabolism. 268 60

Anticholinergics are the mainstay of pharmacotherapy for overactive bladder (OAB). The anticholinergics used to treat OAB differ in their pharmacological profiles, which may affect their propensity for causing commonly observed adverse effects. The purpose of this is review is to use published clinical data to evaluate the safety and tolerability of commonly prescribed anticholinergics for OAB, provide a context for safety and tolerability in terms of drug pharmacology, summarize the impact of adverse effects on adherence, and discuss the influence of study design on safety and tolerability outcomes. A MEDLINE search was conducted for the period 1990-2010 to identify studies evaluating mechanisms of action, pharmacological profiles, safety issues and adverse events pertaining to anticholinergics used in the treatment of OAB. Compared with immediate-release preparations, the extended-release, once daily and transdermal formulations are associated with lower rates of anticholinergic adverse effects, due to improved consistency in serum levels. The most significant adverse effects in terms of affecting the use of anticholinergics agents are CNS and cardiac disturbances. CNS issues are associated with pharmacological properties such as serum concentration, blood-brain barrier permeability and active transport, and receptor binding affinity. Cardiac safety (corrected QT interval) is more dependent on specific molecular attributes. However, more common but less bothersome adverse effects associated with systemic blockade of the muscarinic receptors include dry mouth, constipation, headache and blurred vision. A high potential for interaction between anticholinergics and drugs that compete with the same pathways for hepatic metabolism via cytochrome P450 and renal excretion increases the risk of adverse effects for both antimuscarinic and associated medications, especially in the elderly, who are more likely to be taking multiple drugs. This literature review demonstrates that all OAB anticholinergics are effective in reducing symptoms of OAB; however, important pharmacodynamic/pharmacokinetic differences between these agents may influence their efficacy and incidence of associated adverse effects. Because OAB is a chronic disease requiring long-term therapy, careful assessment of the pharmacological differences is needed in order to tailor therapy to the individual patient's clinical needs, and thereby maximize the chance of treatment success and long-term adherence to therapy. Since anticholinergic adverse effects are known to affect treatment adherence and persistence, the potential for adverse effects should be considered when selecting treatment for an individual patient.
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PMID:Safety and tolerability profiles of anticholinergic agents used for the treatment of overactive bladder. 2183 Aug 36

The nonnucleoside reverse transcriptase inhibitor etravirine, approved for use in treatment-experienced, HIV-1-infected patients, is a substrate and inducer of cytochrome P450 (CYP) 3A4 and a substrate and inhibitor of CYP2C9/CYP2C19. Pharmacokinetic interactions and safety of etravirine 200 mg twice daily coadministered with fluconazole 200 mg daily or voriconazole 200 mg twice daily, both inhibitors of CYP3A4, CYP2C9, and CYP2C19, were evaluated in an open-label, randomized, 3-period crossover trial in 18 HIV-negative volunteers. Based on least squares means (LSM) ratios, coadministration of etravirine with fluconazole or voriconazole resulted in higher etravirine exposures (area under plasma concentration-time curve from 0-12 hours [AUC(12) (h) ] 1.86- and 1.36-fold, respectively). Fluconazole pharmacokinetics were unchanged with etravirine coadministration (AUC(12) (h) LSM ratio: 0.94), and voriconazole plasma concentrations were slightly raised (AUC(12) (h) LSM ratio: 1.14). All treatments and combinations were well tolerated, with no grade 3 or 4 adverse events observed during treatment. There was 1 adverse event-related trial withdrawal during treatment with fluconazole alone (leukocyturia). The most frequent adverse events were headache and blurred vision (11 and 8 volunteers, respectively), with blurred vision occurring exclusively during voriconazole-alone treatment. Pharmacokinetic interactions between etravirine and fluconazole or voriconazole are not expected to be clinically relevant; no dose adjustments are required during coadministration.
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PMID:Pharmacokinetics and short-term safety of etravirine in combination with fluconazole or voriconazole in HIV-negative volunteers. 2340 Jul 42

Drug interaction is a frequent situation in pediatrics and child psychiatry. Carbamazepine (CBZ) is an antiepileptic drug used as a mood stabilizer in child psychiatry. CBZ is known to be a potent inducer of various CYP isoenzymes of cytochrome P450, which might result in a decrease in the plasma concentration of associated treatments. We describe two cases of CBZ overdosage in adolescent inpatients (14 and 16 years). The patients were treated with risperidone associated with fluoxetine in one and with loxapine in the other case, and CBZ was introduced as a mood stabilizer. Patients presented typical clinical symptoms (fatigue, dizziness, gastrointestinal signs, blurred vision). Overdosage was confirmed by an elevated CBZ plasma concentration (17 and 15.5 mg/L, therapeutic range 4-12 mg/L). We recommend introducing CBZ very progressively in patients treated with psychotropics, particularly when it is associated to several treatments. An intensification of clinical and biological follow-up with early plasma concentration testing should allow for better treatment adjustment.
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PMID:[Carbamazepine and psychotropic treatment interaction: Two case studies of carbamazepine overdosage]. 2581 31