Pharmacology and Toxicology Notes PDF

PHARMACOLOGY AND TOXICOLOGY PRINCIPLES OF PHARMACOLOGY I WO N G C H U N K E U N G 2 SEP 2024 1 PHARMACOLOGY Pharmacology - Scientific study of the effects of drugs and chemicals on living organisms Drug - Natural or synthetic chemical substance that affect a biolo...

PHARMACOLOGY AND TOXICOLOGY PRINCIPLES OF PHARMACOLOGY I WO N G C H U N K E U N G 2 SEP 2024 1 PHARMACOLOGY Pharmacology - Scientific study of the effects of drugs and chemicals on living organisms Drug - Natural or synthetic chemical substance that affect a biological system https://www.sharinginhealth.ca/sih/modules/pharmacology.html 2 IMPORTANCE OF PHARMACOLOGY Understand the biochemical and physiologic aspects of drug effects Determine the effectiveness and safety of drugs Help in the diagnosis, prevention and treatment of diseases. https://elifesciences.org/articles/70148 3 TOXICOLOGY Toxicology - The field of science that studies the harmful and adverse effects of chemicals, substances, physical agents or situations, that have on living organisms, and the environment https://www.slideserve.com/chance/toxicology 4  DRUG–RECEPTOR INTERACTIONS Concern with the ability of a drug to affect a given receptor Probability or strength of the drug to occupy a receptor at any given time - Drug's affinity inhibit on Degree to which a drug or ligand activates the receptors S and resulting in the cellular offert response - Intrinsic efficacy dungs https://www.youtube.com/watch?v=X9TkD8DbomY 6  affect effect drugs on Ractors EFFECT OF A DRUG DEPENDS ON: Disease states: – Chronic kidney diseases affects dramatically the drug pharmacology y i t to – Pharmacokinetics studies how body does to the drug Number of Receptors: – Differentially expressing of receptors mediate biological responses of different levels Drug dosage: – Increase in drug amount increase drug effect until saturation of receptor Drug potency/affinity: – More potent drug – Faster binding to receptor and slower releasing from receptor Drug efficacy – Ability of drug to block or activate the receptor 10 DOSE-RESPONSE RELATIONSHIP The most important concept in pharmacodynamics is the dose-response relationship which describes the dependence of the effect of a drug from its concentration at its receptor Pharmacodynamics describes the course of action of drugs leading to the physiological effect at a specific site in the body 16 FOUR MAIN PHARMACOKINETIC PROCESSES e Four main components of pharmacokinetics include: Absorption, distribution, metabolism and excretion (ADME) They are used for explaining the various characteristics of different drugs in the body The pharmacokinetic processes may be influenced by: – Patient factors such as the sex, age, genetics, and diseases – The properties of drugs such as protein binding, molecule size, and chemical characteristics 21 MECHANISMS OF ABSORPTION OF DRUGS FROM THE GASTROINTESTINAL (GI) TRACT Passive diffusion: Vast majority of drugs absorbed by this mechanism Driving force: Concentration gradient across a membrane separating two body compartments Moving of drug: From an area of high concentration to one of lower concentration Passive diffusion does not involve a carrier https://www.nonstopneuron.com/post/factors-affecting-drug-absorption-route- specific-factors Whalen, K. (2023). Lippincott Illustrated Reviews: Pharmacology (Lippincott Illustrated Reviews Series) (8th ed.). LWW. 30 MECHANISMS OF ABSORPTION OF DRUGS FROM THE GASTROINTESTINAL (GI) TRACT Facilitated diffusion Specialized transmembrane carrier proteins allowing passage of drugs into interior of cells Does not require energy It facilitates the passage of large molecules Can be inhibited by compounds competing for the carriers https://nayturr.com/types-of-diffusion/ Whalen, K. (2023). Lippincott Illustrated Reviews: Pharmacology (Lippincott Illustrated Reviews Series) (8th ed.). LWW. 31  BIOAVAILABILITY It is the rate and extent that an administered drug reaches the systemic circulation Determining the bioavailability is important – Especially for calculating the drug dosages for the nonintravenous routes of administration Example: 100 mg of a given drug is administered orally by patient  60 mg is absorbed unchanged, What is the bioavailability? Whalen, K. (2023). Lippincott Illustrated Reviews: Pharmacology (Lippincott Illustrated Reviews Series) (8th ed.). LWW. 38  BIOAVAILABILITY Example: 100 mg of a given drug is administered orally by patient  60 mg is absorbed unchanged, What is the bioavailability? Answer: The bioavailability is 0.6 or 60% Whalen, K. (2023). Lippincott Illustrated Reviews: Pharmacology (Lippincott Illustrated Reviews Series) (8th ed.). LWW. 39  DRUG DISTRIBUTION - VOLUME OF DISTRIBUTION Features of Drugs affecting the Volume of Distribution Acid-Base Characteristics ⑪ Drugs may have a propensity to- bind proteins throughout the body Reach a point of equilibrium between a bound & unbound phase I Basic (alkaline) molecules - I pH high Strong interactions with negatively charged phospholipid head groups located on phospholipid membranes Will leave the systemic circulation leading to higher Vd as compared to acidic molecules Acidic molecules 2 9 capillary · blood. es Higher affinity for albumin molecules at lower lipophilicity than neutral or basic molecules More likely to bind albumin and remain in the plasma Leading to lower mine Vd as compared to more basic molecules 49 DRUG DISTRIBUTION - VOLUME OF DISTRIBUTION Features of Drugs affecting the Volume of Distribution Lipophilicity IU lipid -> leave bloodstream -> ↑(d) Lipophilic molecules More likely to pass through lipid bilayers More likely to leave the bloodstream and distribute to areas with high lipid density such as adipose tissue ->Pat (Guarcoler 504) Have a higher Vd -> Nrd) Hydrophilic molecules IX lipid -> stay bloodstream Less likely to pass through lipid bilayers More likely to remain in the bloodstream Have a lower Vd 50