Pharmacology Study Guide 1 What is a Drug Drug any chemical agent that affects living processes excluding food A substance that has physiological effect when ingested or otherwise introduced into the body At a cellular and molecular level a drug is an exogenous substance that alters body or cellular function physiology The Ideal Drug Produces Only One Effect The Effect That is Sought No drug produces one and only one effect Specificity of drug action one vs multiple molecular mechanisms of action o SSRI antidepressants limit the number of side effects because it works with one mechanism of action Selectivity of drug action one vs multiple effects The ideal drug would be highly specific only one mechanism of action and highly selective only one effect the desired effect Undesired Effects Most drugs produce minor side effects that may be annoying but can be tolerated or which may lessen or disappear over time Adverse Drug Reactions ADR s are most serious and harmful to the patient o Often are life threatening and can sometimes result in death o May require hospitalization and intervention to prevent permanent harm to the patient o Can sometimes result in permanent disability Streptomycin results in hearing loss in some patients o Example allergic reaction ADR s Are a Common Clinical Problem Pharmacological Adverse Reactions dose dependent and predictable related to the pharmacokinetic properties how drug levels go up and down of the drug and resolve when the dose is reduced molecular mechanism of drug o Solution reduce the dose Idiosyncratic Adverse Reactions not related to the known pharmacology of the drug do not show any simply dose response relationship and resolve only when treatment is discontinued o Dose independent and unpredictable o Allergic reaction to a drug the first time indicates it will occur again Mechanisms of Idiosyncratic Adverse Drug Reactions Pharmaceutical Variation eosinophilia myalgia syndrome with L tryptophan Receptor Abnormality malignant hyperthermia increase in body temperature with general anesthetics Abnormal Biological System Unmasked primaquine induced hemolysis of RBC s in patients deficient in glucose 6 phosphate dehydrogenase G6PD deficiency causes the patient to have a short list of drugs that they can take Abnormalities in Drug Metabolism isoniazid induced peripheral neuropathy in people deficient in the enzyme N acetyltransferase patients who are slow acetylators which is a recessive gene that makes a patient vulnerable to an exaggerated drug response because it is building up Immunological penicillin induced anaphylaxis or Stevens Johnson syndrome o Stevens Johnson syndrome looks like a sunburn and the whole skin can come off life threatening Drug Drug Interactions if a patient as they age increases the number of diseases they have it gets difficult to predict the reactions of many different drugs together idiosyncratic reaction Multifactorial Concept All Drugs Are Potential Poisons It is just a matter of dose Even water can be fatal Key Terms Subspecialty Pharmacodynamics the biologic actions of drugs the drug effects the molecular mechanisms of drug action pharmacologists focus on this subspecialty Pharmacokinetics quantitative study of drug absorption distribution metabolism and excretion involving mathematical models provides a rationale for TDM therapeutic drug monitoring changes that occur to the drug while it is inside the body o Blood levels of drugs can be measured to ensure the patient is in a o For a lot of drugs this is unnecessary but a few drugs have a narrow therapeutic drug concentration therapeutic window More Key Terms biologic effects Drug Receptors macromolecular sites at which drugs bind to initiate their o Structural complementarily between the drug and receptor are the basis for the lock and key concept of drug receptor interaction analogous to enzyme substrate interactions o Binding causes a drug effect to be produced Agonist a drug which binds to a specific receptor and consequently Receptor Antagonist a drug which binds to a specific receptor but does not produces a biologic effect produce any biological effects o It can reverse or prevent agonist drug actions o Example heroin as an agonist and neloxyocone as receptor antagonist A Drug Classification Cased on Origin Natural Products alcohol tobacco belladonna leaves poppy plant Pure Compounds isolated from natural products o Nicotine atropine morphine Semi Synthetic Drugs modified chemically alkaloid o Homatropine heroin Purely Synthetic Compounds use chemical reactions to build a larger molecule o Fentanyl Biotechnology Products use cells to synthesize drugs recombinant DNA technology r somatotropin o Growth hormone somatotropin from fermented bacteria that are spliced and genes are inserted in their genome B and C Drug Classifications Classification Based on Therapeutic Use Example diagnostics cure specific diseases alleviate pain analgesics or other symptoms Antihypertensives to lower blood pressure anti gout drugs to treat gout Classification Based on Site and or Mechanism of Action Example antihistamines anticholinergics cholinomimetics Cardiovascular drugs used as antihypertensives includes the B blockers that block B adrenergic receptors Uses of Drugs in Society Prescription Meds OTC s over the counter medications o Requires no prescription Drug abuse misuses Accidental poisoning or deliberate suicide Industrial and agricultural use o Heath Ledger combination of drugs Management of Drug Therapy Planning and implementing strategies to o Maximize therapeutic effects of drug therapeutic range where drug produces an effect and minimize the adverse effects of drugs Assessment of core drug knowledge pharmacology Assessment of core patient variables o Factors which modify drug responses Alcohol how much How often the liver has been damaged in a chronic alcoholic the doses that are used need to be reduced substantially Cigarettes o Includes a complete drug history Patient and family education o When the patient is unable to do it themselves child on a drug treatment or a senior citizen who may have some memory issues Management of Individual Drug Treatment Core Drug Knowledge o Pharmacotherapeutics study or use of a drug for a specific medical condition o Pharmacokinetics o Harmacodynamics o Contraindications and Precautions Off Label Use illegal for a company to give a sales pitch for a drug or its effects that was not previously approved by the FDA Birth Control