Chapter 4 Factors Influencing Drug Effects

Chapter 4Factors Influencing Drug Effects • Patient Factors • Drug Factors

Drug Patient Dosage regimen drugs, doses, intervals, duration Efficacy, adverse effects, concentrations Adjustment Doctor

Part APatient Factors • 1.Physiological Factors • 1.1 Age • Children • Sensitivity to drugs • Pharmacokinetic properties • Elderly • Sensitivity to drugs • Pharmacokinetic properties

Part APatient Factors • 1.2 Body Weight • Volume of distribution • Fat / skeletal muscles • lipid-soluble / water-soluble drugs

Part APatient Factors • 1.3 Sex • Women • Pregnancy • - malformation and dysfunction of the fetuses • Lactation • - milk: effects on infants

Part APatient Factors • 1.4 Individual variation (个体差异) • (1) Sensitivity to drugs • Hypersensitivity • Hyposensitivity (tolerance) • (2) Abnormal responses to drugs • Idiosyncracy (genetic abnormality) • Allergy (immunological abnormality)

Part APatient Factors • 2.Psychological Factors • Placebo effects • Placebo effects commonly are manifested as alteration of mood, other subjective effects, and objective effects that are under autonomic or voluntary control.

Part APatient Factors • 3.Pathological Factors • Heart diseases • Hepatic diseases • Renal diseases • Gastrointestinal diseases • Malnutrition • Imbalances of acid-base or electrolytes

Part APatient Factors • 4.Genetic Factors • Pharmacogenetics • abnormality of drug responses • example:tolerance of warfarin • abnormality of pharmacokinetic properties • example:fast- or slow acetylation

Part APatient Factors • 5.Chronobiological Factors • Circadian rhythms

Part APatient Factors • 6.Life Styles and Environment Factors • Nutrition • Drinking & smoking • Environmental poisons

Part BDrug Factors • 1. Physic-chemical properties of drugs • 2. Dose forms • 3. Administration • 4. Multiple-drug therapy • 5. Long-term drug therapy

Part BDrug Factors • 1. Physic-chemical properties of drugs • Stability • Molecular size • Lipid- and water soluble • ……

Part BDrug Factors • 2. Dose forms • slow release formulation • controlled release formulation • sustained release formulation • transdermal patch • inhalation

Part BDrug Factors • 3. Administration • Doses • Routes oral • intramuscular injection • subcutaneous injection • intravenous injection or infusion • Administration time • Dosing intervals • Dosing duration

Part BDrug Factors • 4. Multiple-drug therapy (drug combination) • Drug-drug interactions pharmacy • pharmacokinetics • pharmacodynamics • Drug effects in combination synergism • antagonism • potentiation • addition

Part BDrug Factors • 5. Long-term drug therapy • Tolerance (tachyphylaxis) and resistance • Dependence • Withdrawal syndrome

二、机体方面的因素 • Box 1 • Physical dependence（生理依赖性） • 生理（身体）依赖性是指大多数具有依赖性特征的药物经过反复使用所造成的一种适应状态，用药者一旦停药，将发生一系列生理功能紊乱，称戒断综合征（withdrawal syndrome）。

二、机体方面的因素 • Box 2 • Psychological dependence or psychic dependence（精神依赖性） • 精神依赖性是指使人产生一种对药物欣快感的渴求，这种精神上不能自制的强烈欲望驱使滥用者周期性或连续地用药。精神依赖性与身体依赖性的主要不同点是前者在停药后不出现严重的戒断症状。

二、机体方面的因素 • Box 3 • Drug addiction（药物成瘾） • 药物成瘾是指强迫性、失去控制的用药行为，是药物的精神依赖性和身体依赖性共同造成的结果 • Drug addiction is a progressive and often fatal behavioural syndrome characterized by compulsive drug seeking and consumption despite serious negative consequences.

Chapter 4 Factors Influencing Drug Effects