Unraveling the Role of COMT Polymorphism in Dopamine-Mediated Vasopressor Effects: An Observational Cross-Sectional Study.

AIMS: To evaluate the association between rs4680 polymorphism in the COMT gene and the vasoconstrictive effects of commonly used vasopressors. BACKGROUND: Dopamine is a medication that is given intravenously to critically ill patients to help increase blood pressure. Catechol O-Methyl Transferase (COMT) breaks down dopamine and other catecholamines. There is a genetic variation in the COMT gene called rs4680 that can affect how well the enzyme works. Studies have shown that people with this genetic variation may have different blood pressure levels. However, no one has looked at how this genetic variation affects the way dopamine works to increase blood pressure. OBJECTIVES: To investigate the impact of the rs4680 polymorphism in the COMT gene on the pharmacodynamic response to dopamine. METHODS: Critically ill patients administered dopamine were included following the consent of their legally acceptable representatives. Details on their demographic characteristics, diagnosis, drug-related details, changes in the heart rate, blood pressure, and urinary output were obtained. The presence of rs4680 polymorphism in the COMT gene was evaluated using a validated method. RESULTS: One hundred and seventeen patients were recruited, and we observed a prevalence of rs4680 polymorphism in 57.3% of our critically ill patients. Those with mutant genotypes were observed with an increase in the median rate of change in mean arterial pressure (mm Hg/hour) [wild: 8.9 (-22.6 to 49.1); heterozygous mutant: 5.9 (-34.1 to 61.6); and homozygous mutant: 19.5 (-2.5 to 129.2)] and lowered urine output (ml/day) [wild: 1080 (21.4 to 5900); heterozygous mutant: 380 (23.7 to 15800); and homozygous mutant: 316.7 (5.8 to 2308.3)]. CONCLUSION: V158M (rs4680) polymorphism is widely prevalent in the population and was significantly associated with altered effects as observed clinically. This finding suggests valuable insights into the molecular basis of COMT function and its potential impact on neurotransmitter metabolism and related disorders. Large-scale studies delineating the effect of these polymorphisms on various vasopressors are the need of the hour.

Evaluation of the Association between Single Nucleotide Polymorphisms of Metabolizing Enzymes with the Serum Concentration of Paracetamol and Its Metabolites.

Intravenous paracetamol is a commonly administered analgesic and antipyretic in inpatient settings. Paracetamol is metabolized by cytochrome P450 (CYP) enzymes followed by conjugating enzymes to mainly glucuronide but to a lesser extent, sulphate metabolites, and oxidative metabolites. Single nucleotide polymorphisms (SNPs) in the CYP enzymes result in modified enzymatic activity. The present study was carried out to evaluate the prevalence of SNPs related to paracetamol metabolism and principal metabolites in critically ill patients, and those with chronic kidney disease. The present study is a cross-sectional study carried out in adults (>21 years) requiring intravenous paracetamol as part of their standard of care. Details regarding their demographics, and renal and liver function tests were collected. Blood was withdrawn for the analysis of paracetamol and their metabolites, and the SNPs of key CYP enzymes. Paracetamol/paracetamol glucuronide (P/PG), paracetamol/paracetamol sulphate (P/PS) and PG/PS were estimated. Acute liver injury (ALI) and renal dysfunction were defined using standard definitions. We observed a significant prevalence of SNPs in CYP1A2*1C, CYP3A4*3, CYP1A2*1K, CYP1A2*6, CYP2D6*10, and CYP2E1*2 amongst the 150 study participants. Those with CYP1A2*6 (CC genotype) were observed with significantly lower PG and PS concentrations, and a higher P/PS ratio; CYP2D6*10 (1/1 genotype) with a significantly lower PG concentration and a higher P/PG ratio; and CYP1A2*1K (CC genotype) was observed with a significantly higher PG/PS ratio. Good predictive accuracies were observed for determining the SNPs with the cut-off concentration of 0.29 µM for PS in determining CYP1A2*1K, 0.39 µM for PG and 0.32 µM for PS in determining CYP1A2*6 genotype, and 0.29 µM for PG in determining the CYP2D6*10 genotype. Patients with renal dysfunction were observed with significantly greater concentrations of paracetamol, PG and P/PS, and PG/PS ratios, with a lower concentration of PS. No significant differences were observed in any of the metabolites or metabolite ratios in patients with ALI. We have elucidated the prevalence of key CYP enzymes involved in acetaminophen metabolism in our population. Alterations in the metabolite concentrations and metabolic ratios were observed with SNPs, and in patients with renal dysfunction. Population toxicokinetic studies elucidating the dose-response relationship are essential to understand the optimized dose in this sub-population.

Evaluation of Pharmacogenetics of Drug-Metabolizing Enzymes and Drug Efflux Transporter in Renal Transplants Receiving Immunosuppressants.

Cytochrome P450 (CYP) enzymes, such as CYP3A4, and CYP3A5, P450 oxidoreductase (POR), peroxisome proliferator activated receptor alpha (PPAR-alpha), and drug transporter (ABCB1) were observed to influence concentrations of immunosuppressants (cyclosporine, everolimus, sirolimus, and tacrolimus) and outcomes in renal transplants. We carried out the present study to evaluate the prevalence and impact of these single nucleotide polymorphisms (SNPs) in adult renal transplants. SNPs were evaluated using commercial TaqMan® assays. Serum drug concentrations were estimated using immunoassays. One hundred and forty-six patients were recruited. SNPs in CYP3A5*3 were significantly associated with greater dose-adjusted cyclosporine and tacrolimus concentrations. SNPs in POR*28 were observed with significantly lower dose-adjusted concentrations, particularly with cyclosporine and tacrolimus. ABCB1 homozygous polymorphisms were observed with significantly lower time spent in the therapeutic range with cyclosporine and everolimus/sirolimus. Cyclosporine was observed in a significantly greater proportion of patients with elevated GGT, and SNPs in PPAR-alpha were significantly associated with an increased risk of this adverse event. Hypertriglyceridemia with everolimus was significantly associated with POR*28 polymorphisms. There is a need to validate the influence of these SNPs in a prospective study and develop an algorithm predicting the achievement of target concentrations.