Pharmacogenetics in the clinic Flashcards
(58 cards)
What factors contribute to variable inter-individual drug response?
- Demographic
- Environment
- Co-morbidities
- Drug-drug interactions
- Genomic variation
What percentage of patients benefit from drug therapy?
30-60%
What is the percentage of adverse drug reactions (ADRs) that lead to hospitalization?
6.5%
What is pharmacogenomics?
Study and response of the genetic determinants of drug response
What percentage of phase-dependent metabolism of clinically used drugs is mediated by CYP families 1-3?
70-80%
What was the first P450 enzyme purified to homogeneity?
CYP2B4
What do polymorphic forms of P450s lead to?
Development of significant number of adverse drug reactions (ADRs)
What is the cost implication of treating patients with polymorphic forms of P450s?
Higher than those with non-polymorphic alleles
What percentage of subjects are non-responders to drug therapy?
Around 30-60%
What is the role of the 10,000 Genomes project?
Sequencing the whole genome of families with rare diseases and patients with common sequences
What does CPIC stand for?
Clinical Pharmacogenomics Implementation Consortium
What proportion of the population carries at least 1 actionable pharmacogenetic variant?
98.5% of Whites and 99.1% of African-Americans in the US
What is the function of CYP2C19 in relation to clopidogrel?
Prodrug requiring activation by CYP2C19
What is the effect of the 11 genotype on platelet aggregation when treated with clopidogrel?
Reduction in platelet aggregation
What are the genotypes of a CYP2C19 poor metaboliser?
2/2
3/3
2/3
What is the therapeutic outcome for a CYP2C19 poor metaboliser?
Avoid clopidogrel if possible; use prasugrel or ticagrelor
List the options for statins.
- Atorvastatin
- Fluvastatin
- Lovastatin
- Pitavastatin
- Pravastatin
- Rosuvastatin
- Simvastatin
What role does SLOC1B1 play in the metabolism of statins?
Facilitates the hepatic uptake of statins
What is the association of the ABCG2 variant p.Q141K with rosuvastatin?
Associated with 30-40% reduced protein expression and increased plasma levels of rosuvastatin
What are the two most extensively studied variants of CYP2C9?
- CYP2C9*2 (p.R114C)
- CYP2C9*3 (p.I359L)
What is statin induced myopathy?
Ranges from mild myalgia to very rare but life-threatening rhabdomyolysis
What does the SLOC1B1*5 variant indicate?
Higher plasma levels cause muscle toxicity
What is the significance of diplotypes in pharmacogenomics?
Haplotype pairs on homologous chromosomes
What treatment adjustments are needed for SLOC1B1 decreased function?
Treatment varies based on SAMS risk; high, moderate, or low intensity statins