NURS 6521 Mid-Term Summary & Study Guide: Pharmacokinetics, 2023 Latest File

Pharmacokinetics: • Understand the implications of changing renal function on creatinine and drug dosing. Impaired renal function decreases body’s ability to metabolize drugs  increased plasma drug levels  need for decreased drug dosage • What is the impact of the following on drug levels and dosing: o Cirrhosis – drug metabolizing enzymes (cytochrome P-450) are decreased due to loss of function liver tissue  decreased rate of metabolism  increased levels of drug & accumulation of toxic levels  prevent accumulation by reducing or discontinuing drug with cirrhosis o Protein binding – • changes effective concentration of the drug at its site of action by changing the rate drug is eliminated • restriction of drug distribution - o drugs bound to albumin can’t leave blood stream because albumin is a big molecule, thus drug cannot reach site of action or undergo metabolism/excretion until protein bond broken • can be a source of drug interactions – one drug can displace another from albumin causing free concentration of displaced drug to rise  intensity of drug response  toxicity • Can affect biological half life o Example: Warfarin – 97% is bound, 3% unbound and actually active and may be excreted  levels can increase to toxicity d/t decreased excretion rate • Need to saturate drug binding proteins before receptors activated o Drug interactions – may need to decrease or increase dosages of drugs or choose alternative drug all together 1. One drug may intensify the effects of the others (i.e. sulbactam inhibiting enzyme of ampicillin and thus prolonging and intensifying therapeutic effects OR aspirin and warfarin increasing bleeding adversely) 2. One drug may produce a new response not seen with either drug alone (i.e. ETOH and Antabuse causing nausea when combined, but not when taken individually) 3. One drug may reduce the effects of the other drug (i.e. propranolol reducing albuterol’s therapeutic effect by blocking effects of albuterol in the lungs OR naloxone used to treat morphine overdose by blocking morphine’s action) o Half-life – index of how quickly a drug is metabolized and excreted; drug half life is determined by the time required for the amount of drug in the body to decrease by 50% o Determines drug dosing interval; for a drug with a short half life, the drug interval must be short and conversely a drug with a long half life can have longer half life without losing benefit Routes of Administration and Dosage Forms: • Understand the different routes of administration and dosage forms and some of the challenges and benefits associated with these routes and forms HTTPS://WWW.MERCKMANUALS.COM/HOME/DRUGS/ADMINISTRATION-AND-KINETICS-OF-DRUGS/DRUG-ADMINISTRATION 1. Oral a. Convenient, safest, least expensive b. Given in higher doses d/t being absorbed through small intestine before transported to blood stream; amounts are reduced through absorption in small intestine and liver (metabolizing) chemically altering drugs c. Can be altered by other food and drugs in digestive tr