Basic Veterinary Pharmacology Lecture Notes PDF

Cherry R. Alvarez, DVM, PhD VPHM 50 Laboratory Cherry R. Alvarez, DVM, PhD Associate Professor 1 DBVS, CVMBS, CvSU PhD Animal Science – UPLB Major: Animal Nutrition Minor: Human Nutrition MS Animal Science – UPLB Major: Animal Nutrition Minor: Biochemistry Doctor of Veterinary Medicine Cavite St...

Cherry R. Alvarez, DVM, PhD VPHM 50 Laboratory Cherry R. Alvarez, DVM, PhD Associate Professor 1 DBVS, CVMBS, CvSU PhD Animal Science – UPLB Major: Animal Nutrition Minor: Human Nutrition MS Animal Science – UPLB Major: Animal Nutrition Minor: Biochemistry Doctor of Veterinary Medicine Cavite State University Long Examinations: 75% Quizzes: 15% Class participation: 5% Collaborative Output (Class/Group Project): 5% Passing: 70% Pre final grade will constitute 70% of your final grade. Final Exam will constitute 30% of your final grade. Exemption from taking the final exam: Prefinal grade of 73%, No score below 60 in the long examinations. https://www.frontiersin.org/journals/veterinary- science/articles/10.3389/fvets.2021.777809/full ✓ To learn about drugs used in veterinary medicine ✓ To recognize when NOT to use drugs ✓ To know that a drug can be a poison “Drugs can be poison; what differentiate a poison from a remedy is the dose.” - Theophrastus Philippus Aureolus Bombastus von Hohenheim (Paracelsus) - is any chemical agent that affects living organisms. - In clinically setting drugs are used to diagnose, prevent, and cure diseases and disorders of living organisms (patients), and for purposeful alteration of body functions, such as in sedation, anesthesia, and estrus synchronization in farm animals. ✓ You cannot possibly learn everything about every drug available. ✓ You must try to organize the material. ✓ Remember things instead of memorizing. ✓ Develop a flexible framework for drug information. ✓ The best approach is to learn drug by their class. Dr. Elito Landicho (UPCVM) Pharmacology (from Greek pharmacon = drug and Latin logos = study) - the science and study of drugs and their interaction with living organisms. - uses the tools of both chemistry and biology. Chemistry studies the physical properties of matter (chemicals). Biology studies mainly the structures, functions, development, and relationships of and among living organisms. Drug - is any chemical agent, other than food, that affects the structure and functions of living organisms (Broad definition) - is any substance, food or nonfood, that is used to treat, cure, mitigate, or prevent diseases including any nonfood substances that are intended to affect the structure or function of the individual (Legal or regulatory definition). Food may be defined as any article that is eaten or drunk that provide taste, aroma, or nutritive value. Nutraceutical simply refers to nutrient used as drugs. 1. Pharmacodynamics is the science and study of HOW drugs produce their effects on living organisms. It involves the site (where a drug act) and the mechanism of action (how drugs act) in producing an effect. a. Pharmacokinetics is a subdivision of pharmacodynamics that deals with the physiological processes and factors that determines the amount of drug at its site of action at various times between its application to and elimination from the body. 2. Toxicology is the study of the harmful effects of drugs, and the conditions under which these harmful effects occur. 3. Pharmacotherapeutics (or simply therapeutics) is concerned with the useful application of drugs in the diagnosis, prevention, mitigation and cure of diseases, and in the purposeful alteration of body structure and functions. 4. Pharmacy is the art and science of developing, preparing, compounding, and dispensing of drugs. As an art, pharmacy is an older discipline that pharmacology, but still is considered a branch of the broader science of pharmacology. a. Pharmacognosy is a subdivision of pharmacy that studies (plants, animals, mineral, or synthetic) sources of drugs. b. Metrology is a subdivision of pharmacy that deals with weights and measures of drugs. c. Posology is a subdivision of pharmacy that deals with formulating drug dosages. 1. Molecular pharmacology - concerned with the study of basic mechanisms of drug action on biological systems - aims to determine and interpret the relationship between biologic activity and structures of molecules or groups of molecules. 2. Clinical Pharmacology is mostly concerned with the rational development, effective use, and the proper evaluation of drugs for the diagnosis, prevention and cure of diseases. It also deals with the safe use of drugs in animals and humans. It applies to both veterinary and human medicine. 3. Veterinary pharmacology vs. Medical (human) pharmacology: Veterinary pharmacology is concerned with drugs as they are used in the diagnosis, prevention and treatment of animal diseases, and in the intentional alteration of animal physiology. Although many of the same drugs may be used in animals and humans, there are differences in the dosage, effects, and usefulness of drugs between animals and humans. The range of animal species in which drugs are used distinguishes veterinary pharmacology from medical pharmacology. What category of pharmacology is specifically concerned with each of the following? a. Determining the safe dose and dosing frequency of aspirin cats b. Describing the mechanism of nicotinic receptor antagonism by a newly develop muscle relaxant drug c. Using beta adrenergic blocker in alleviating dilated cardiomyopathy in dogs and cats d. Treating leukemia in a 29-year old woman with L-asparaginase A drug act to produce an effect (maybe useful or harmful). A drug action is the mechanism or manner by which a drug produces an effect. A drug effect is the change the drug produces in a subject (organism). Effect – relief of fever, pain, and inflammation Action – inhibition of cycloxygenase enzyme that catalyzes the formation of prostaglandins, which mediate fever, pain and inflammation. ▪ Binding to a specific receptor, or ▪ Nonspecific physicochemical means Pharmacological effect refers to exaggerated change in the function or condition in an individual caused by a drug. Physiological effect refers to an effect that promotes and maintains normal body function. Insulin when given in proper dose to a hyperglycemic individual causes the blood sugar to reduce to normal. When given in excess, insulin leads to hypoglycemia ▪ A dose of a drug may be poisonous to one but not to another. ▪ Basis for chemotherapy (use of chemical to kill or inhibit infective, parasitic living organism (pathogen) or suppress uncontrolled cellular growth such as tumors (cancers) which produce disease in the host patient. ▪ Example: penicillins (including ampicillin, amoxicillin, and methicillin), cephalosporins, vancomycin, and bacitracin. Peptidoglycan/murein - forms the cell walls of many bacteria ▪ A drug can only enhance or reduce the functions of which the individual is NATURALLY capable. ▪ The effect of a drug is therefore always quantitative (altering the magnitude or degree of a body function) and NOT qualitative (altering the nature of the function) ▪ No drug is capable of conferring x-ray vision on an animal, or the ability cause ovulation in a normal male, because these are qualitative attributes. ▪ Antibacterial ▪ Antiviral ▪ Antifungals/Anti mycotic ▪ Antiprotozoan ▪ Antineoplasm ▪ Anthelmintic Drug Receptor ▪ A drug receptor is a specialized target macromolecule that binds a drug specifically and mediates its pharmacological action. ▪ involved in chemical signaling between and within cells; they may be located on the cell surface membrane or within the cytoplasm The receptors may be: ▪ Enzymes, Nucleic acid, or Specialized membrane-bound proteins ▪ Ligands - molecules (drugs, hormones, neurotransmitters) that bind to a receptor - binding maybe specific and reversible or irreversible. - may activate or inactivate a receptor; activation may increase or decrease a particular cell function. Selectivity is the degree to which a drug acts on a given site relative to other sites; selectivity relates largely to physicochemical binding of the drug to cellular receptors. https://www.msdmanuals.com/professional/clinical-pharmacology/pharmacodynamics/drug%E2%80%93receptor- interactions Drug’s effect on a given receptor (by virtue of chemical structure): 1. Drug affinity – probability of the drug occupying a receptor at any given instant 2. Intrinsic efficacy – (intrinsic activity—degree to which a ligand activates receptors and leads to cellular response Drug – Receptor complex (Residence Time) - Transient drug occupancy - Prolonged occupancy ▪ Variation among tissues - receptor, efficiency of stimulus- response mechanisms ▪ Drugs ▪ Aging ▪ Genetic mutations ▪ Disorders ▪ The receptor with which a drug binds nonspecifically and does not lead to perceptible pharmacological effect is called an acceptor rather than a receptor. ▪ Examples of acceptor include plasma albumin and nonspecific tissue proteins. ▪ prohibits the drug from binding to the receptor and thus inactivates the drug. ▪ The specificity of drug action appears to be determined by a certain molecular shape of the drug (that is quite complementary to the shape of the receptor). ▪ Any slight change to the drug structure causes a change in the intensity of drug effect. This principle is called the structure- activity relationship (or SAR). ▪ A drug and its receptor generally have complementary chemical structure similar to lock and key. ▪ Most important concept in drug development. ▪ a compound that binds to a receptor and produces the biological response. activate receptors to produce the desired response. Dose-response relationship, the intensity of the biological response is directly proportional to the amount (dose) of the drug that binds with receptors. An agonist can be a drug or the endogenous ligand for the receptor *Isoproterenol binds with the same beta-adrenergic receptors that the endogenous substance epinephrine acts on. An agonist is like a key that fits the keyhole and opens the lock. ▪ An agonist must be able to fit into the receptor – affinity. ▪ It must have an inherent (or built-in) ability to induce a biological response – intrinsic activity. ▪ Many hormones, neurotransmitters (eg, acetylcholine, histamine, norepinephrine), and drugs (eg, morphine, phenylephrine, isoproterenol, benzodiazepines, barbiturates) act as agonists.