10. Factors of the patient that affect drug action – drugs in pregnancy, breast-feeding, children, elderly, liver and kidney diseases. Genetic abnormalities and drug action.

Factors of the patient that affect drug action- drugs in pregnancy, breast-feeding, children, elderly, liver and kidney diseases. Genetic abnormalities and drug action

1. Drug Factors:

• Chemical Structure: The drug's molecular configuration influences its interaction with receptors and its overall pharmacological activity.
• Physical and Chemical Properties: Properties such as solubility, stability, and pH affect absorption, distribution, metabolism, and excretion.
• Physical State: The drug’s state (solid, liquid, gas) affects its absorption and efficacy. For instance, gaseous anesthetics are inhaled, while solid drugs are typically ingested. ↑ quick
• Dose and Dosage Form: ↳ slower The amount and form (e.g., tablet, injection) impact the drug's effectiveness and speed of action.

2. Patient Factors:

• Age: ↑ sensitivity
• Neonates and Infants: Absorption can be slower, but IM absorption is quicker. Distribution is different due to higher water content and lower body fat. Plasma protein binding is reduced, and the BBB is more permeable. Metabolism is immature, and renal elimination is reduced, necessitating dose adjustments. ↳ Grey baby
• Elderly: Absorption may be slower due to reduced GI motility. polyhypovitaminosis Distribution is affected by decreased lean body mass and body water. Metabolism slows due to decreased liver function, and elimination is reduced, requiring careful dose management.
• Sex: Hormonal differences can affect drug metabolism and efficacy.
• Pathological Conditions: Conditions like liver or kidney disease can alter drug metabolism and excretion, potentially leading to toxicity.
• Genetic Abnormalities: Genetic variations can affect enzyme activity, impacting drug metabolism. For instance, glucose-6-phosphate dehydrogenase deficiency can cause hemolytic anemia with certain drugs.
• Circadian Rhythms: The body's biological clock can influence drug absorption and metabolism, potentially affecting drug efficacy and timing.
• Weight: Body weight affects drug distribution, with higher body fat leading to increased storage of lipid-soluble drugs, while lower body fat might increase the concentration of such drugs in the bloodstream.
• Pregnancy:
• Absorption: Reduced GI motility but increased IM absorption.
• Distribution: Increased body water and fat affect drug distribution. Plasma albumin declines.
• Metabolism: Increased due to elevated hormone levels, affecting drugs like phenytoin and theophylline.
• Elimination: Increased clearance for many drugs, requiring dose adjustments.
• Contraindications: Certain drugs like chloramphenicol and warfarin are contraindicated due to potential harm to the fetus. Rifampicin lincosamides
• Breast-Feeding: tetracyclin aminoglycosides
• Maternal Plasma Concentration: Drugs enter milk via passive diffusion, influenced by their lipid solubility, size, and protein binding.
• Drug Characteristics: Lipid-soluble drugs and those in un-ionized form cross more readily into milk. More Acidic
• Concomitant Diseases:
• Absorption: Surgery and gut conditions can impair nutrient absorption.
• Distribution: Conditions like hypoalbuminemia increase the free drug concentration in plasma.