Summary Nur312 Pharmacology-Pharm Basics Pharmacology Comprehensive Review

NUR312 PHARMACOLOGY-PHARM BASICS PHARMACOLOGY COMPREHENSIVE REVIEW • Concepts to Understand How do drugs exhibit their effects? How long does it take for drugs to work? How do the liver and kidneys influence drug metabolism? BIOLOGICAL EFFICACY • The phrase biological efficacy refers to the ability of a drug to exert its desired therapeutic effects • In other words, how well did the drug work for the patient? • Most drugs work by complex metabolic actions of the liver and kidneys and many variables influence the effects of the drug on the body and the effects of the body on the drug BIOAVAILABILITY: • Refers to the ability of drugs to exert their effect • It involves physiological concepts such as reaching the target cell PHARMACOKINETICS • The term pharmacokinetics refers to the effect that the body has on the drug • It involves the movement of the drug, which influences the manner in which a drug behaves in the body over time • It involves the phases of absorption, distribution, metabolism, and elimination • Conditions such as renal and hepatic disease impact this mechanism • It’s essential for nurses to understand this concept so they may identify which drugs might be inappropriate for a patient PHARMACODYNAMICS • The term pharmacodynamics refers to the effect that the drug has on the body • This is influenced by the mechanism of action • The response of the drug is controlled by pharmacodynamics SERENDIPITY • The term serendipity refers to the unexpected clinical effects of a medication • A prime example is Viagra, which was originally created as a antihypertensive, was then marketed for erec- tile dysfunction when it was discovered to have an effect on this condition • Nurses are in the optimal position to be aware of the unexpected effects of drugs and report them KNOW YOUR “RIGHTS” Rights of Med Administration Patient Medication Dose Route Time Documentation Place Situation NEED TO KNOW LAB VALUES These are the labs you need to know with normal values. • ABGs: pH 7.35-7.45 CO 35-45 HCO3 22-26 • • CBC HCT W (36-45) M (42-52) Hgb W (12-15) M (42-52) WBC 5-10k (Questions generally associated with low WBC) PLT 200k-400k (200k=concern) BUN 5-20 Chloesterol (Total) 200 Glucose 70-100; 120 fasting is indicative of diabetes HgbA1C 4.6%; 7% : indicative of uncontrolled diabetes Potassium 3.5-5 Sodium 135-145 Creatinine 0.6-1.2 PTT, APTT 25-35 sec for non-therapy and 2xs for normal on therapy INR 2-3 Coumadin; 0.8-1.2 not on coumadin NEED-TO-KNOW PHARM TERMS • The therapeutic effect is the desired response or outcome of administering a drug • The term mechanism of action refers to the process that the drug uses to produce the desired therapeutic effect • Indications are situations in which use of the drug is considered appropriate; or simply the approved rea- sons to use the drug • Off-label use describes a situation in which use of the drug is not considered an indication (or approved use) but may be effective in certain cases • Contraindications are situations in which the drug should not be administered. For example, heparin, a powerful anticoagulant that’s given to prevent blood clots from forming, should be withheld in a patient who suffered a recent fall as it can increase the risk of hemorrhage. Therefore, a recent fall is a contraindi- cation of heparin • Onset of action refers to the duration of time it takes for the drug to exert its effects following administra- tion. In regards to drugs with a high addictive risk profile (risk for addiction), those with shorter half-lives are more likely to be abused • The term half-life refers to the amount of time that it takes for a drug to be metabolized half-way. This con- cept can often be used to predict how long it takes for a drug to work, exert its full effect, and last in the system. For example, • Peak action refers to the period of time in which a drug exerts the most powerful effects. This is the dura- tion in which the patient is at the greatest risk of side-effects. Example: When administering insulin, the nurse must be extra-vigilant in monitoring for signs of hypoglycemia during the period of time marked by the peak-action • First-pass effect/metabolism is the effect that the hepatic system has on the drug, which is often metabo- lized by into a different chemical form. This mechanism impacts the use of various drugs, including the route of administration (such as IV over oral). For instance, some substances are broken down completely as they’re metabolized via the oral route, and therefore rendered ineffective by the time they reach systemic circulation (the blood stream); so they’re only given by IV. The first-pass effect is also manipulated to make draw upon the effects of the by-product that’s produced after a substance is metabolized (the by-product is what’s effective). Hepatic function is required for many drugs to exert the desired therapeutic effect • A drug monograph is a summary of a medication that includes key points that describe how it works, uses (indications), and how to administer it HOW DRUGS ARE NAMED Chemical Names • Chemical names are assigned by the International Union of Pure and Applied Chemistry (IUPAC) • Chemical names are usually extremely long and complex Trade Names- almost always capitalized • Trade names are assigned by the pharmacological company that is marketing the drug for sale • The trade names is often easy to pronounce (“catchy”) and may be influenced by more by marketing con- cepts (designed to elicit a certain thought or feeling) rather than pharmacological ones Generic Names • Generic names are assigned by the U.S.Adopted Name Council • Following expiration of the patent, other companies are free to manufacture generic versions of the drug • Generic names are generally not capitalized SYSTEMS OF MEASUREMENT Metric Measurement • Volume: Liters (L) or milliliters (mL) • Cubic centimeter (cc is the abbreviation, although it is no longer recommended for use, due to risks of er- rors) • Weight: Kilograms (kg), grams (g), micrograms (the abbreviation is no longer recommended for use, mu) Household Measurement • Ounces (oz) • Tablespoon (Tbs), teaspoon (tsp) • Discourage the use of household items to measure drugs for administration to due inconsistency in size • FDA and Drug Approval THE APPROVAL PROCESS • America has the most stringent drug approval process in the world. Drug approval is overseen by the Fed- eral Drug Administration (FDA). Extensive research must be conducted prior to approval. There are ben- efits and downfalls to this. There are several phases of approval, including preliminary approval. • Stages of the FDA Approval Process • Preclinical investigation • Clinical investigation • Review of the New Drug Application • Post marketing surveillance DRUG APPROVAL Advantages of the Drug Approval Process • America boosts safe drug administration • Consumers are more aware of the risks Disadvantages of the Drug Approval Process • Drug approval can take up to 15 or more years • Due to the wait, many drugs that are available in Europe, such as cancer drugs, are still seeking approval in the States • The process is incredibly expensive, which has created an environment in which large pharmaceutical com- panies have monopolized the market as smaller companies cannot compete • Research is often generally conducted by the pharmaceutical companies, which poses concerns over con- flict of interest • Drug manufactures may exclusively sell a medication until the patent expires, at which time generic substitutes may go to market, which substantially lowers the price. DRUG MONITORING The Purpose of Therapeutic Monitoring • Drug monitoring is necessary for drugs that have a narrow therapeutic range, meaning that there’s a fine line between effective and toxic. It provides data on concentration-to-efficacy-to-toxicity relationships to ensure that the level is high enough to be effective, yet low enough to prevent toxicity. Therapeutic moni- toring is also important for patients with certain disease states the impact the way drugs are metabolized, such as kidney failure. A common method of drug monitoring involves the regular collection of blood sam- ples to monitor for fluctuations in serum. Common Forms of Therapeutic Monitoring • Hemodynamic effects: The effect of the drug on certain hemodynamic (blood monitoring) parameters. Ex- ample: PT/INR is used to monitor patients on warfarin therapy by measuring the time it takes for a sample of blood to clot • Blood concentration monitoring: The amount of the drug present in the blood. Example: Lithium levels are monitored on patients receiving treatment. It’s monitored more frequently during the first few weeks • Peak and trough: Used to titrate potent drugs such as the antibiotic vancomycin Common Drugs that Require Monitoring and Titration Warfarin (Coumadin) Digoxin Heparin Lithium • Therapeutic monitoring is necessary for drugs that have a narrow therapeutic range. INTERACTIONS AND CONTRAINDICATIONS • Pharmacodynamic interactions is another way of describing drug-to-drug interactions, or undesired effects that occur when more than one drug is used concomitantly • Concomitant use describes the use of two or more drugs within the same period. The drugs do not necessar- ily have to be administered at the same time to be considered concomitant, but they must span of time in which they exert their effects must overlap • Drug-to-food interactions describe undesirable effects that are exerted if a particular food interacts with the use of a drug. A prototype example to be aware of is grapefruit. This fruit contains a molecule that enhances the effects of many different drugs, which increases the risk of the patient experiencing toxicity DRUG-TO-DRUG INTERACTIONS Drug-to-drug interactions refers to interactions that occur when two drugs are used concurrently (at the same time). They may antagonize (cancel out or reduce) the effects (referred to antagonists) or agonize (enhance) the effects (re- ferred to as agonists). Antagonizing the effects can cause the drug to be less effective. Agonizing the effects in- creases the risk of toxicity or overdose to occur (subtherapeutic). For example, concomitant use of diphenhydramine (Benadryl, an antihistamine) and oxycodone (Percocet, an opioid) can act as agonists that enhance the effects on the central nervous system and may increase the risk of respiratory sedation. HIGH ALERT DRUGS High alert drugs include a group of medications that are considered particularly dangerous as incorrect administra- tion can lead to devastating, sudden, and potentially life-threatening effects. Hospitals and other health care facilities usually have policies in place that require another qualified and competent nurse to double check the drug prior to administration. The Joint Commission teamed up with the Institute for Safe Medication Practices (ISMP) to take the lead on this issue (International Society for Quality in Health Care, 2001). In collaboration, they formed a “High Alert Drug List.” This list is periodically updated (ISMP, 2013). Example High Alert Drugs Heparin Insulin Opiods Potassium Chloride or Phosphate Solutions Sodium Chloride solutions above 0.9% ABBREVIATIONS AND SAFETY • Do Not Use List • The Joint Commission publishes a “Do Not Use List” for abbreviations, symbols and acronyms that have been linked to high rates of medication errors. Proper use of decimals is imperative to patient safety. In ad- dition to the Joint Commission’s list, there are several other abbreviations and symbols that have demon- strated increased risk of errors through evidence based research (Glassman, 2013). • Official “Do Not Use” List* • * From the Joint Commission’s Official “Do Not Use” List, 2013 DECIMALS Safe Use of Decimals in Drug Administration • Proper use of decimals is imperative to patient safety. Evidence-based research suggests that improper use of decimals is associated with increased incidents of medication errors (Glassman, 2013). The Joint Commission also provides guidelines on the proper use of decimals for medication administration safety. Following these rules reduces the risk of miscommunication between nurses, physicians, and other team members of the inter- disciplinary team. Trailing zeros should not be used (example: 2.10 mL should be written as 2.1 mL). Decimal Errors • Do NOT use a trailing zero; example: 1.0 mL is incorrect (if the reader doesn’t see the decimal, it could easily be mistaken for 10 mL, a ten-fold difference in a dose); use 1 mL instead (as it eliminates the possi- bility of a reader interpreting the dose incorrectly) • DO use a leading zero when appropriate; example: 0.1 mL rather than .1 mL • 0.1 mL: Correct (proper use of a leading zero and no trailing zero) • 04.4 mL: NOT correct (correct: 4.4 mL) • 00.1 mL: NOT correct (correct: 0.1 mL) • 0.10 mL: NOT correct (correct: 0.1 mL