ATI Module - Introduction to Pharmacology

‭Drug Categories‬ ‭●‬ ‭Shared therapeutic effects, ADRs, contraindications, precautions, and considerations for‬ ‭administration‬ ‭Generic vs. Brand/Trade Name‬ ‭●‬ ‭Generic and brand-name drugs have the same chemical composition (active ingredients)‬ ‭●‬ ‭Each new generic drug must have the exact therapeutic equivalence as the original‬ ‭brand-name drug (interchangeable)‬ ‭Prescription Drugs‬ ‭●‬ ‭Potentially harmful without‬‭supervision‬‭of administration‬‭by a licensed health provider‬ ‭●‬ ‭Ex.‬‭Antibiotics‬‭, such as ceftriaxone (Rocephin);‬‭antihypertensive‬‭drugs, such as‬ ‭captopril (Capoten);‬‭diuretics‬‭, such as furosemide‬‭(Lasix); and‬‭narcotic analgesics‬‭, such‬ ‭as fentanyl (Sublimaze and Duragesic)‬ ‭Nonprescription/OTC Drugs‬ ‭●‬ ‭Do not require a prescription; relatively safe to take without supervision‬ ‭●‬ ‭Ex. Acetaminophen (Tylenol), ibuprofen (Advil), diphenhydramine (Benadryl),‬ ‭loratadine (Claritin), cimetidine (Tagemet)‬ ‭Oral Drugs‬ ‭●‬ ‭Tablet, capsule, powder, and liquid forms‬ ‭●‬ ‭Drugs taken through the mouth but inhaled into the lungs are usually powder‬ ‭●‬ ‭Enteric-coated (EC)‬‭drugs dissolve when the drug reaches‬‭the‬‭intestine‬ ‭○‬ ‭Do not crush or chew‬ ‭●‬ ‭Extended-release (ER)‬‭drugs release over a period‬‭of time‬ ‭○‬ ‭Extended length (XL), sustained release (SR/XR), or sustained action (SA)‬ ‭●‬ ‭Immediate-release drugs‬‭expedite its release‬ ‭Parenteral/Injectable Drugs‬ ‭●‬ ‭Intravenously into a vein (IV), subcutaneously into subcutaneous tissue (sub-Q),‬ ‭intramuscularly into muscle tissue (IM)‬ ‭●‬ ‭Come in either a liquid form or dry form that needs liquid added (‬‭reconstitution‬‭)‬ ‭Topical/Transdermal Drugs‬ ‭●‬ ‭Drugs applied to a client’s skin, eyes, ears, nose, rectum, vagina, or lungs‬ ‭●‬ ‭Deliver a constant amount of drug over an extended period of time‬ ‭●‬ ‭Transdermal is systemic, while topical is to local site‬ ‭●‬ ‭Slower onset‬‭and longer duration than oral/parenteral‬‭drugs‬ ‭Pharmacokinetics‬ ‭●‬ ‭The absorption, distribution, metabolism, and excretion of drugs‬ ‭Absorption‬ ‭●‬ ‭The movement of drug from site of administration to various tissues of the body‬ ‭●‬ ‭Oral drugs:‬‭Intestinal wall‬ ‭→ portal vein → liver →‬ ‭blood‬ ‭●‬ ‭Inhaled drugs:‬‭Alveoli →‬ ‭blood‬ ‭●‬ ‭First-pass effect: Part of the‬ ‭drug may deactivate when‬ ‭passing through the liver, so‬ ‭the amount available to the‬ ‭body can be less than what‬ ‭was ingested orally‬ ‭●‬ ‭Bioavailability: Amount of‬ ‭the oral drug available after‬ ‭passing through the liver‬ ‭●‬ ‭Parenteral drugs:‬‭Directly through a vein or indirectly‬‭through subcutaneous tissue or‬ ‭muscle → blood (bypassing the first-pass effect)‬ ‭Distribution‬ ‭●‬ ‭Movement of drug by‬‭circulatory system‬‭to intended‬‭site of action‬ ‭●‬ ‭Areas with‬‭rich blood supply‬‭(kidneys, liver, heart)‬‭receive the highest levels‬ ‭●‬ ‭Areas without a rich blood supply (bones) or with a barrier (brain, blood brain barrier)‬ ‭receive lower levels‬ ‭Metabolism‬ ‭●‬ ‭Change of a drug to a more/less potent, soluble, or inactive form‬ ‭●‬ ‭Most drug metabolism occurs in the liver‬ ‭●‬ ‭Biotransformation: When the structure of a drug is chemically‬ ‭altered during metabolism‬ ‭●‬ ‭Metabolite:‬‭New/altered form‬‭of a drug; byproduct‬‭of‬ ‭metabolism‬ ‭Excretion‬ ‭●‬ ‭Elimination of a drug and its metabolites‬ ‭●‬ ‭Kidneys‬‭eliminate drugs through the urine; may‬‭reabsorb‬‭some,‬ ‭allowing it to pass through the body again before excretion‬ ‭●‬ ‭Excretion can also occur through the GI tract, skin, and lungs‬ ‭Drug Half-Life‬ ‭●‬ ‭Half-life: The time it takes for a drug that enters the body to decrease in amount by half‬ ‭●‬ ‭Drugs with a short half-life may have to be administered several times daily‬ ‭●‬ ‭Drugs with a long half-life may only be administered once daily‬ ‭●‬ ‭A decrease in‬‭liver or kidney functioning‬‭could affect‬‭the level of a drug in the body‬ ‭Onset, Peak, and Duration‬ ‭●‬ ‭Onset:‬‭Time it takes to demonstrate a therapeutic‬‭response‬ ‭●‬ ‭Peak effect:‬‭Time it takes the drug to demonstrate‬‭its full therapeutic effect‬ ‭●‬ ‭Duration:‬‭Time a drug’s therapeutic effect lasts without‬‭additional doses‬ ‭●‬ ‭Measures through labs and determines whether a therapeutic level is maintained‬ ‭Pharmacodynamics‬ ‭●‬ ‭Secondary to changes in how cell function, cellular environment (cell structure‬ ‭intereference), or enzyme actions‬ ‭●‬ ‭Agonists:‬‭Drugs that bind with a receptor and precipitate‬‭a greater than typical response‬ ‭●‬ ‭Antagonists:‬‭Drugs that bind with a receptor and either‬‭block a response or precipitate a‬ ‭less than typical response‬ ‭○‬ ‭Competitive:‬‭Antagonists that compete with an agonist‬‭for receptor sites‬ ‭■‬ ‭Rarely blocks a response completely‬ ‭○‬ ‭Noncompetitive:‬‭Antagonists that block an agonist’s access to receptor sites‬ ‭■‬ ‭Can block the typical response in high doses‬ ‭ ‬ ‭Selective drug action: Drug interacts with specific receptor sites to elicit desired effects‬ ● ‭○‬ ‭More selective drugs interact with fewer receptors‬ ‭○‬ ‭Less selective drugs interact with more, causing widespread bodily reactions‬ ‭Expected Pharmacologic Action‬ ‭●‬ ‭The action a drug exerts in the body‬ ‭●‬ ‭Pharmacologic actions can have multiple therapeutic uses‬ ‭○‬ ‭Ex. Diphenhydramine (Benadryl) for antihistaminic, antiemetic, sedative, or‬ ‭anticholinergic effects‬ ‭Adverse Drug Reactions‬ ‭●‬ ‭Nontherapeutic, unintended effects of a drug at a therapeutic dose‬ ‭○‬ ‭Ex. Diphenhydramine causes dry mouth, drowsiness, confusion, uncoordination,‬ ‭dizziness, convulsions, and hyperactivity‬ ‭●‬ ‭Most severe: Allergic reaction; previous exposure increasaes sensitivity‬ ‭○‬ ‭Anaphylactic shock: Exaggerated response of the immune system to a drug,‬ ‭precipitating a massive release of histamine‬ ‭■‬ ‭Swelling of the eyes, face, mouth, and throat‬ ‭■‬ ‭Dyspnea, wheezing, tachycardia, extreme hypotension‬ ‭■‬ ‭Can ultimately lead to cardiac arrest‬ ‭○‬ ‭Tx of focuses on airway re-establishment and oxygen therapy‬ ‭■‬ ‭Administer epinephrine to raise BP and dilate respiratory bronchi‬ ‭■‬ ‭Give diphenhydramine to block histamine release‬ ‭Tolerance, Cumulative Effect, and Toxicity‬ ‭●‬ ‭Drug tolerance:‬‭Body’s decreased response to a drug‬‭received over time‬ ‭●‬ ‭Pharmacodynamic tolerance:‬‭Tolerance associated with‬‭long-term opioid analgesic‬‭use‬ ‭●‬ ‭Drug sensitivity/cumulative drug effect:‬‭Occurs secondary‬‭to metabolic changes, such‬ ‭as‬‭impaired hepatic and renal function‬ ‭●‬ ‭Drug toxicity:‬‭When a client receives drugs in excessive‬‭doses or has impaired excretion‬ ‭○‬ ‭Lowest effective dose to achieve therapeutic effects should be prescribed‬ ‭Precautions and Contraindications‬ ‭●‬ ‭Precautions taken when drugs can cause‬‭ADRs with certain‬‭people‬‭or combinations‬ ‭●‬ ‭Only use when necessary or when the benefits > risks‬ ‭●‬ ‭Additional precaution for pts with chronic/multiple medical conditions‬ ‭●‬ ‭Conduct physical assessment and laboratory monitoring‬ ‭●‬ ‭Limit certain types of food or concurrent drug administration‬ ‭Drug-Drug Interactions‬ ‭●‬ ‭When one drug changes the way another affects the body‬ ‭●‬ ‭Additive:‬‭Combined effect of two drugs given together‬‭equals the sum of each one given‬ ‭alone in similar doses (1+1 = 2)‬ ‭○‬ ‭Ex. alcohol and opioids combine in sedative effect‬ ‭●‬ ‭Synergistic:‬‭The effect of a drug is greater if given‬‭with another drug (1+1 > 2)‬ ‭○‬ ‭Ex. effects of warfarin can intensify when given with aspirin → intense bleeding‬ ‭●‬ ‭Antagonistic:‬‭The effect of a drug is decreased/blocked‬‭if given with another (1+1 < 2)‬ ‭○‬ ‭Ex. bronchodilators given with a CV drug with an ADR of bronchoconstriction‬ ‭results in antagonization‬ ‭Drug-Food Interactions‬ ‭●‬ ‭When food changes the way a drug affects the body‬ ‭●‬ ‭Increased blood levels due to increased absorption or slowed metabolism rate/amount‬ ‭●‬ ‭Decreased blood levels due to decreased aborption or rapid metabolism rate/amount‬ ‭Drugs During Pregnancy‬ ‭●‬ ‭Should only take prescribed drugs (benefit > risk)‬ ‭‬ C ● ‭ an cross through the placenta to the fetus‬ ‭●‬ ‭Categories A, B, C, D, X‬ ‭○‬ ‭D: Possible risk to fetus‬ ‭○‬ ‭X: Fetal malformations associated with drug‬ ‭Drugs During Breastfeeding‬ ‭●‬ ‭Should only take prescribed drugs (benefit > risk)‬ ‭●‬ ‭Can affect infant if drug concentrations in breast milk are high‬ ‭●‬ ‭Consider size of infant and amount of milk consumed‬ ‭Drugs in Neonates, Infants, and Children‬ ‭●‬ ‭Pharmacokinetics vary from adults‬ ‭●‬ ‭Gastric emptying is slower until 6-8 months‬ ‭●‬ ‭Gastric pH is higher until 2 years‬ ‭●‬ ‭Less of a drug is metabolized in the first liver pass-through‬ ‭●‬ ‭Increased intramuscular absorption in infants and children‬ ‭●‬ ‭Higher water and lower body fat content affects distribution‬ ‭●‬ ‭Infants have a less effective blood-brain barrier‬ ‭●‬ ‭Fewer enzymes are produced by the liver until 1 year‬ ‭●‬ ‭The rate at which drugs metabolize from 1-2 years greatly increase‬ ‭○‬ ‭Slows after 2 years but doesn’t reach that of an adult until 12‬ ‭●‬ ‭Excretion of drugs significantly decreases until 1 year due to decreased kidney perfusion‬ ‭●‬ ‭Drug dosage adjustments in relation to age, weight, and body surface area‬ ‭Drugs in Older Adults‬ ‭●‬ ‭Physiologic changes of aging affect pharmacokinetics‬ ‭●‬ ‭Decreased CO, decreased peristalsis, increased GI tract pH, and decreased renal and/or‬ ‭hepatic function‬ ‭●‬ ‭Test liver and kidney function‬ ‭●‬ ‭Anesthetic needed during a procedure and recovery varies related to metabolism and‬ ‭excretion ability‬