Advanced Pharmacology Exam 1 (question and answers)

Once you graduate from an NP program, in order to prescribe you'll need: - -Advanced nurse prescriber license -DEA # What is the purpose of a DEA #? - Needed to prescribed scheduled drugs Rules for prescribing Schedule II drugs: - -Written script needed -1 month supply only -No refills What is the PDMP? - Prescription Drug Monitoring Program Used to effectively track patient's controlled substance uses across different health facilities (in the same state) What are clinical practice guidelines? - Recommendations that are intended to optimize patient care that are informed by a systematic review of the evidence and an assessment of the benefits/harms of alternative care practices Ex: sepsis, CAP Common causes of medication errors: - -Illegible writing -Drug names that sound alike -Medications that look alike -Administering a drug with the wrong route What is pharmacokinetics? What are its 4 categories? - What the body does to the drug 1. Absorption 2. Metabolism 3. Distribution 4. Excretion Quickest route of absorption? Slowest? - IV = quickest IM = slowest What is the most common way drugs pass through cell membranes? - Passive diffusion What characteristics of a drug allow it to pass most quickly through cell membranes (usually through passive diffusion)? - Small, uncharged (unionized), lipid soluble--pass through membrane without any energy What does it mean when a drug is ionized? - It means that the drug is stuck in the compartment it was ionized in and has to be moved to the next compartment (cannot be absorbed into the bloodstream) Where do weak acids absorb? - Stomach Where do weak bases absorb? - Small intestine pH of stomach: - 2-4 pH of small intestine: - 6-7 pH of large intestine: - 6-7 pH of bloodstream: - 7.35-7.45 pH of bladder: - 5-8 pH of breastmilk: - 7.1 Where will a drug absorb if it is a weak base that ionizes at a pH of 4 and lower? - In the small intestine (since the stomach has a pH of 2-4, so the drug will become ionized and move to the small intestine where it will be able to absorb into the bloodstream) How can we manipulate the urine pH in cases of overdose? - Drugs that are weak acids (aspirin) can be trapped and excreted through the urine. We raise pH of the urine (with sodium bicarb) to force the drug to ionize and allow it to be excreted, not reabsorbed through the bloodstream. What is distribution? - How a drug will be transported to the tissues it needs to go to in order for it to exert its effects Drug factors related to distribution: - -Lipid solubility -Molecular size -Degree of ionization -Duration of action -Cellular binding -Therapeutic effects -Toxic effects (lipid soluble, small, and non-ionized drugs will distribute more quickly) Body factors related to distribution: - -Vascularity (poor perfusion, disruption of blood flow due to trauma--difficulty distributing) -Blood barriers (blood-brain-barrier can be problematic if we need to get drugs to the brain--will need very high dosing since only a small amount of the drug will get through) -Transport mechanisms -Plasma binding proteins -Disease states -Volume of distribution -Drug interactions What is the key plasma protein involved with protein binding for medications? - Albumin Why do we monitor albumin? - Indicative of nutritional status and how well protein-bound drugs will be transported to their target locations What happens to the therapeutic effect of a drug when the patient is elderly and has very low levels of albumin? - The drug does not bind to the protein (albumin) as much as expected, so there is a lot of free drug floating in the plasma; high risk for drug toxicity Protein bound means: - Inactive form of the drug; does not have any therapeutic effect when bound to a protein Free drug means: - Active form of the drug (available for therapeutic effect) What happens when a patient is on two drugs that are competing for the same protein binding site on the albumin? - Some drug interactions can occur. Drugs fight for binding position, but both drugs do not get enough as the usually would. Leads to higher free drug levels, decreased overall albumin binding, and potential toxicity for both drugs. **Unpredictable** What is the 1st pass effect? - PO drug goes through GI tract and absorbs in the stomach or intestines into local circulation that reaches the liver. The liver inactivates portions of the drug before it goes into systemic circulation. Some drugs with a very high 1st pass effect may have to be given IV (goes directly into systemic circulation) or in higher PO doses (watch for side effects) What does a substrate for an enzyme mean? - It needs it to undergo metabolism What is an enzyme inducer? - It increases clearance of the drug (decreased blood levels of drug--may need dose increase) What is an enzyme inhibitor? - It reduces clearance (increased blood levels of drug--may need dose decrease) Who is at risk for drug toxicity? - Elderly, those with decreased renal function -Cannot properly excrete the drug What are the key pharmacokinetic changes that occur during pregnancy? - -Decreased absorption -Increased hepatic metabolism -Increased renal excretion **Dose adjustments are common during pregnancy What is the safest drug category for pregnant women? - Category A What is the contraindicated drug category for pregnant women? - Category X What is pharmacodynamics? - What the drug does to the body What is a drug's half-life? - The time it takes for the concentration of a drug in the body to be reduced by 50% How many half-lives does it take to remove most of the drug from the body? - Appx 4 Why is knowing half-life important? - When switching to another drug that cannot be given with the previous drug. How to determine when drug will be cleared from body: - Multiply half-life of drug by 4 Ex: Half-life of drug A = 8 hours 8 x 4 = 32 hours (how long you'd need to wait before starting the contraindicated new drug B) What is therapeutic index? - Statement of the relative safety of a drug Which is safer: a wide TI or a narrow TI? - A wide TI is safer (more dosing options before reaching toxic effects) What is the minimum effective concentration? - The minimum amount of drug required to produce a therapeutic effect What is receptor desensitization? - Decreased responsiveness of the receptor to the drug; decreased overall effects How does antibiotic resistance occur? - The bacteria find a way to become resistant to the antibiotic. They multiply leading to an ineffective antibiotic How to prevent antibiotic resistance: - -Don't prescribe for viral infections -Only prescribe when needed