Lecture 1: Pharmacotherapeutics

Nurs 116 Pathopharmacology Lecture 1: Pharmacotherapeutics Pharmacology: the study of medicines ↳ purpose is to cure, relieve symptoms, and/or improve quality of life Pharmacotherapeutics: the administration of drugs for the purpose of disease prevention or treatment and relief of suffering Drug: a chemical agent capable of producing biological responses in the body ↳ these responses are desirable (therapeutic) or undesirable (adverse) ↳ a drug that is medically therapeutic is called a medication 3 Categories of Pharmacotherapeutics: ① Drug/Medication = a chemical agent ② Biologic = naturally produced in animal cells eg. hormones, antibodies, blood products, genetic treatment modalities ③ Natural Health Product (NHP) = naturally occurring, used as a supplement eg. vitamins, minerals, dietary supplements - - - Table is a little different than the one in class Health Canada evaluates/monitors safety, efficacy, quality and advertising of drugs Placebo in Clinical Trials · Placebo: a substance that has no effect, but is said to have an effect, making you feel like the intended effects (placebo effect) ↳ used in clinical trials as a "control" · Declaration of Helsinki: ethical principles for medical research involving human subjects ↳ placebos are no longer allowed in clinical trials, in order to compare drugs the testing drug is compared to a drug with similar properties used at the time ↳ it is unethical to not give treatment (placebo) Drug Classes Nomenclature ① Therapeutic ↳ name specifies a treatment/therapy of a particular disease/disorder eg. antiinflammatory ② Pharmacological ↳ name specifies molecular and tissue activity "mechanism of action" (how it works) eg. beta blocker All the same 3 Types of Drug Names: ① Chemical ↳ the chemical composition is the drug name ↳ assigned by IUPAC (international union of pure and applied chemistry) ② Generic*** ↳ assigned name (international nonproprietary name) ③ Brand/trade ↳ named by the manufacturing company ↳ many names for the same drug (eg. Advil = Ibuprofen = Motrin) Brand Name Vs. Generic · Cost - generic is cheaper (and covered by more insurance companies) · Bioequivalence - the biochemical similarity of two (or more) drugs that share the same active ingredient(s) and the desired outcome(s) for patients A - assessment D - diagnosis P - planning I - implementing E - evaluation Prototype Drugs · Prototype drug: the well-understood drug model with which other drugs in a pharmaceutical class are compared · knowing prototype drug helps predict actions and adverse effects of other drugs in the same class · usually the "original drug" of that kind or the most used drug in that class Drug Schedules Pharmacotherapeutics are an Intervention · Before any drug is administered, the nurse must obtain and process pertinent information regarding the client's medical history, physical assessment, disease process, and learning needs + capabilities · Drugs are a form of medical intervention given to improve the client's condition or to prevent harm Subjective vs. Objective data What patient tells you Factors Affecting Drug Administration Route: · drug to target tissues (where is it going?) · clinical setting (IV is easier, oral is faster) · medical situation (how urgent) · drug dynamics (how the drug works) Routes not mentioned: implanted ports, vaginal, intraosseous, epidural + spinal (intrathecal) Parenteral Measurable/quantifiable assessments Routes of Administration: 1. Oral (PO) 2. Sublingual (SL) 3. Intranasal (insufflation) 4. Inhalation 5. Endotracheal (ET) 6. Topical 7. Transdermal 8 Rectal (PR) 9. Intravenous (IV) 10. Intramuscular (IM) 11. Subcutaneous (SC) 1. Oral (PO) PO Drugs Absorbed by · by mouth the Gastric Mucosa: · "enteral" → passes through GI tract · caffeine · most challenging in regards to kinetics (how the drug moves through the body) · warfarin (coumadin) ↳ if drug is acidic take w/o food, if drug is basic take w/food · alcohol (ETOH) ↳ enters portal circulation (liver) → 1st pass metabolism (biotransformation) · dilantin (phenytoin) · systemic effect (more side effects) · aspirin (ASA) Mnemonic: Cats Will Always Demand Attention - 2. Sublingual (SL) · under the tongue → faster absorption because it doesn't reach GI tract · capillary absorption into bloodstream · systemic effect - 3. Intranasal (insufflation) · into the nasal cavity · capillary absorption · localized or systemic effect (based on preparation) ↳ local effect eg. Rhinocort spray (34% still reaches systemic) ↳ systemic effect eg. flu vaccine ↳ direct effect eg. cocaine (diffusion across mucosa & distribution along CNS nerve network) - - - 4. Inhalation · breathed into lungs · pulmonary capillary network → rapid effects · localized or systemic effects (based on preparation) ↳ local effect eg. asthma drugs (some reaches systemic) ↳ systemic effect eg. general anesthesia drugs - - 5. Endotracheal (ET) · ER/ICU situations eg. epinephrine (never oral medication) 6. Topical · applied directly to surface (skin, eye creams, ointments, liquids) · local effect · minimal systemic presence ↳ many molecules are too large to penetrate all skin layers eg. retinoid creams (for wrinkles) have local effect at reticular layer of dermis (collagen fiber repair & synthesis); low systemic effect but contraindicated in pregnancy - 7. Transdermal · "patch" · dermal capillary absorption ↳ molecules must be small enough to penetrate skin layers · systemic effect desired · long acting → slow a steady release and absorption eg. nitroglycerine patch, nicotine patch, morphine patch - 8. Rectal (PR) · inserted into the lower GI, rectum · local and systemic effect ↳ low 1st pass metabolism ↳ systemic effect unreliable, many factors affecting it - 9. Intravenous (IV) · needle-catheter into a vein · immediate absorption → fast onset of action · can control dosage · systemic effect · infection risk, expensive - 10. Intramuscular (IM) · needle injection into muscle tissue ↳ aqueous (faster effect) or depot preparation (slower effect) · capillary bed absorption into bloodstream · systemic effect · painful - * - 11. Subcutaneous (SC) · injection into adipose tissue of hypodermis · absorption via capillary bed · systemic effect (faster or slower based on preparation) eg. insulin A * - & ⑧ Pharmacokinetics: the study of drug movement throughout the body, and how the body handles medications ↳ movement across cell membranes via phospholipid bilayer ↳ 4 phases: ADME (absorption, distribution, metabolism, excretion) - - Molecular Kinetics is Affected by: 1) Molecular characteristics ↳ charge (ionization) → ionized (polar), non-ionized (nonpolar) ↳ acid-to-acid, base-to-base ↳ lipophillicity vs. hydrophilicity ↳ size 2) Membrane transport ↳ passive (gradient) ↳ active (ATP) ADME General Rule: · lipophilic, non-ionized, small = easy absorption & distribution · hydrophilic, ionized = easy excretion - - - Absorption of Medications · Absorption: the movement of a drug across membranes into systemic circulation ↳ the faster the absorption, the faster the onset of drug action · Factors affecting absorption: ① administration route ② molecular characteristics · Types of drugs that should not be chewed, crushed, or opened: ① extended-release formulations ② enteric-coated drugs ③ drugs with oral cavity effects Plasma Drug Concentration/Bioavailability · bioavailability: the amount of drug that is absorbed into systemic circulation and physiologically available to reach its target cells and exert its effect · measurable via blood tests and urinalysis · known for most standard doses · can adjust dose to achieve desired patient effect: titrating to effect ↳ to patient response (eg. pain) ↳ to blood urine concentrations (bioavailability) First Pass Metabolism · drugs absorbed from the stomach and small intestine first travel to the liver, where they may be inactivated before they ever reach their target organs - a process called 1st pass metabolism (first pass effect) · When something is metabolized/biotransformed it gets denatured or altered and then inactivated ↳ inactivated substances are then excreted by the kidneys through urine · When drugs get biotransformed by the liver, some of it is stored in bile in the gallbladder from the bile reabsorption in the duodenum ↳ this leads to reabsorption and recirculation through bile (biliary recirculation) ↳ drugs then leave through feces · note: some drugs react in the liver and cannot be taken together Drugs with Extensive First Pass Metabolism (cannot be given orally, or requires super high dosages) · Morphine · Meperidine (Demerol) · Diazepam (Valium) · Midazolam · Lidocaine · Propanolol · ETOH (alcohol) Mnemonic: My Mom Does More Lovely Paintings Hepatic PORTAL vein → Liver → Hepatic vein + Alcohol - - . . . . - Therapeutic Range · minimum effective concentration: the amount of drug required to produce a therapeutic effect ↳ onset of action · therapeutic range: the plasma drug concentration between the minimum effective concentration and toxic concentration (this is the goal) → T max · toxic concentration: the level of drug that will result in serious adverse effects · plasma half-life (t1/2): the length of time required for a medication to decrease concentration in the plasma by one-half (50%) after administration ↳ the greater the half-life, the longer it takes for a medication to be excreted ↳ determines frequency of administration ↳ it takes 4 half lives before a drug is "functionally eliminated" (94% removed) - T-max ⑧ T-mit TV2 O O Loading Dose and Maintenance Dose · loading dose: a higher amount of drug, often given only once or twice, that is administered to "prime" the bloodstream with a level to quickly induce a therapeutic response · maintenance dose: are given to keep the plasma concentration within the therapeutic range - - - Recommended Doses · the "recommended" therapeutic dose should be enough to elicit a therapeutic effect based on clinical trials · ED 50: median therapeutic dose (dose required to produce an effect in 50% of patients) ↳ a range is recommended because everyone reacts differently · TD 50: median toxicity dose (50% of patients toxic response) · TI (therapeutic index): the ratio between TD 50 : ED 50 ↳ calculation: TD 50/ED 50 = TI ↳ smaller number = higher risk Narrow TI Meds: · Digoxin (Lanoxin) · Warfarin (Coumadin) · Phenytoin (Dilantin) · Tacrolimus (Prograf, Astagraf) Mnemonic: Don’t Worry, People Talk - - - lont G - 2x the recommended dose is toxic (risk of overdose)