Expert opinion on drug metabolism & toxicology
-
Expert Opin Drug Metab Toxicol · Oct 2012
ReviewADMET considerations for restless leg syndrome drug treatments.
Restless legs syndrome (RLS) is a common neurological disorder that might impair nocturnal rest causing decreased alertness, depressed mood, reduced job performance, and poor quality of life. In patients affected by severe RLS, a pharmacological treatment is mandatory. ⋯ Clinical trials have showed that non-ergolic dopamine agonists are efficacious and safe for patients affected by moderate to severe idiopathic RLS. However, no head-to-head study has compared the long-term effects of the three dopamine agonists approved by the FDA for RLS (ropinirole, pramipexole, and rotigotine). Moreover, further studies should investigate the extended-release formulation of ropinirole and pramipexole in RLS patients affected by all day long distressing symptoms. A standardized treatment for symptomatic forms of RLS is lacking. Randomized, placebo-controlled trials should be performed at least in RLS patients with peripheral neuropathic and chronic kidney disease. Concerning RLS due to iron deficiency, a head-to-head study comparing efficacy, safety and compliance of oral iron versus intravenous one seems to be needed.
-
Expert Opin Drug Metab Toxicol · Jun 2012
ReviewCytochrome c: potential as a noninvasive biomarker of drug-induced acute kidney injury.
Acute kidney injury (AKI) in critically ill patients is closely associated with increased morbidity and mortality, yet there remains continued reliance on increased serum creatinine and blood urea nitrogen to diagnose AKI. These biomarkers increase only after significant renal structural damage has occurred. Recent research efforts have focused on discovery and validation of novel serum and urine biomarkers to detect AKI prior to extensive structural damage. Cytochrome c is best known as an indicator of cell death burden in any organ or tissue. It is released during mitochondrial damage that is associated with processing of apoptosis, cell lysis during necrosis and even reversible mitochondrial and cell injury. ⋯ Cytochrome c, as a biomarker, has the potential to improve outcome for AKI patients. Its release indicates mitochondrial damage, one of the earliest changes in cell injury and death. New mitochondrial-targeted therapeutics may be designed around this molecule. Its disadvantages include only transient increase at expression levels that are easily measurable and nonspecificity for kidney injury. The appropriate and optimal utilization of cytochrome c as a biomarker for AKI will be realized only after its complete characterization in experimental and clinical arenas.
-
Expert Opin Drug Metab Toxicol · Mar 2012
ReviewCytochrome P450 variations in different ethnic populations.
Variability of drug response is an important consideration in clinical medicine. A major determinant of drug response variability is hepatic cytochrome P450 oxidase (CYP450)-mediated drug metabolism. Advances in genetics permits genotyping large numbers of patients to identify single nucleotide polymorphisms (SNPs) which may result in variant CYP450 enzyme expression and/or activity. New SNPs with functional impacts are constantly being identified which further explain variability in CYP450 phenotype. ⋯ Racial/ethnic differences in metabolic phenotype can be explained by differences in SNP distribution. However, overlap in substrate specificity, linkage disequilibrium and previously unidentified SNPs have made phenotypic characterization difficult for CYP3A4/5 and 2C8/9. Studies utilizing newly identified, highly prevalent, racially stratified SNPs and their impact on CYP isoform-specific metabolism will provide new answers.
-
Expert Opin Drug Metab Toxicol · Feb 2012
ReviewPharmacokinetics of alteplase in the treatment of ischaemic stroke.
Alteplase is the only approved drug for thrombolysis in acute ischaemic stroke (AIS) after its initial use in acute myocardial infarction (AMI). Its role in functional recovery is time-dependent while its major adverse effect, intracranial haemorrhage, is dose-dependent. These underline the importance of the pharmacokinetics of alteplase to its clinical use. ⋯ The pharmacokinetic profile of alteplase is almost entirely derived from studies in AMI. Differences in the pathophysiology of AMI and AIS mean it cannot be assumed that the pharmacokinetics of alteplase is similar in these two populations. During AMI, cardiac function and, hence, hepatic perfusion and clearance of alteplase may be impaired. The relatively older population in AIS may have impaired metabolic clearance which may increase plasma concentrations. The concurrent use of medications such as nitrates in the management of elevated blood pressure during AIS thrombolysis is also associated with reduced plasma concentrations of alteplase. Again, differences in clot size and type between AMI and AIS and between subtypes of AIS may influence response to alteplase. There is an inherently higher risk of intracranial haemorrhage in AIS compared to AMI emanating from cerebral infarction and BBB disruption. Accordingly, stroke-specific pharmacokinetics of alteplase and its relationship to efficacy and safety outcomes are required.
-
Expert Opin Drug Metab Toxicol · Nov 2011
ReviewPharmacokinetic evaluation of pixantrone for the treatment of non-Hodgkin's lymphoma.
Pixantrone is a novel aza-anthracenedione, similar in structure to anthracyclines, including the anthracycline derivative mitoxantrone. There is no standard therapy for relapsed or refractory aggressive non-Hodgkin's lymphoma (NHL) in patients who have received two prior lines of therapy. Pixantrone does not bind iron, promotes reactive oxygen species to a lesser degree than other anthracyclines and is therefore believed to be less cardiotoxic without compromising efficacy. ⋯ Pixantrone is an active and safe drug that has been shown to be of benefit when used to treat patients with relapsed aggressive NHL in the context of Phase II and Phase III studies. It was superior to other single-agent therapies in this context and in combination therapy may be the treatment of choice in order to avoid cardiac toxicity. Potentially it is a more effective and less cardiotoxic alternative to doxorubicin in patients with aggressive NHL.