How may a polymorphism or mutation affect a patient s response to analgesics anticonvulsants and other pain related pharmacotherapies?
Polymorphism is a change in genotype that has an incidence of greater than 1% of the population. The most common cause of genetic variability is a single nucleotide change.
In contrast, mutations occur in less than 1% of the population with higher occurrence of multisequence changes due to deletions, inversions, and duplications.
The genotype/phenotype of the majority of a species population is called the wild type .
Genetic variations exist at several levels: there are variants for transporters like P-glycoprotein for facilitation of absorption or distribution after a drug is consumed, metabolic enzymes such as cytochrome P450 enzymes affecting the conversion of the parent drug to active or inactive metabolites, and variants affecting enzymes responsible for enhancing excretion of a drug metabolite by making it more soluble for renal or fecal excretion through glucuronidation or sulfate conjugation.
All in all, the response to a given drug may be enhanced, diminished, or made toxic or ineffective depending on the type of genetic polymorphism and influence any of the pharmacokinetic stages.