Why do individuals respond differently to certain medications?

Individuals respond differently to medications primarily due to genetic variations, specifically single nucleotide polymorphisms (SNPs). SNPs are variations at a single position in a DNA sequence among individuals and can influence how genes function. These variations can affect drug metabolism, efficacy, and the likelihood of experiencing side effects. For example, some people may have SNPs that alter the expression of drug-metabolizing enzymes, leading to faster or slower breakdown of medications in their bodies. This genetic variability helps to explain why the same dose of a drug can have markedly different effects on different individuals, making it a critical factor in personalized medicine.

While environmental factors and dietary habits can also influence drug response to some extent, they do not account for the inherent biological differences that arise from genetic makeup. Variations in drug manufacturing processes can contribute to the consistency and reliability of medications but do not directly explain the differences in individual responses to those medications.