2023 Clinical Pharmacology Exam Test Bank Questions And Correct Answers

2023 Clinical Pharmacology Exam Test Bank Questions And Correct Answers What is pharmacokinetics? - ANSWER- what the body does to the drug What is pharmacodynamics? - ANSWER- what the drug does to the body What are the five top PK parameters? - ANSWER- 1. Clearance [Cl] 2. Half life [t 1/2] 3. Fractional oral bioavailability [F] 4. Fraction excreted unchanged [fe] 5. Volume of distribution [Vd] What are some causes of a 'minimum effective concentration' of a medicine? - ANSWER- Non-adherence, under prescribing, decreased bioavailability, increased metabolism [enzyme induction, pharmacogenetics]. What are some causes of an above 'minimum toxic concentration' of a medicine? - ANSWER- Over-dose, renal impairment, reduced metabolism [liver impairment, enzyme inhibition, pharmacogenetics] What are the variables in a one compartment model? - ANSWER- Amount of drug, concentration, elimination rate Elimination rate units - ANSWER- Mg/hr Clearance units - ANSWER- L/hr What is half life of elimination - ANSWER- The time for the concentration of a drug to halve What is volume of distribution - ANSWER- A proportionality constant relating the plasma concentration to the total amount of drug in the body OR The volume into which a drug appears to be distributed with a concentration equal to that of plasma What is loading dose - ANSWER- The dose of drug required to fill the volume of distribution to achieve a target plasma concentration. OR simply the dose of drug required to quickly reach a target concentration. What can increased volume of distribution - ANSWER- Large size, leaky membranes [eg sepsis due to vasodilation and capillary leak], change in body composition [eg oedema], decreased plasma protein binding [liver/renal failure or drug interactions]. Provide an example of a maintenance dose rate - ANSWER- Paracetamol oral 1g four times a day Rate of elimination [RE] equation - ANSWER- RE [mg/hr] = Cl [L/hr] x Cp [mg/L] What is the best index of drug exposure - ANSWER- Area under the concentration-time curve What is the significance of t 1/2 - ANSWER- Important for calculating dose interval and the time to steady state (4-5 half lifes) What is metabolism - ANSWER- Drug metabolism is the enzymatic conversion of one chemical (drug) into another (metabolite). It usually involves converting a biologically active molecule to one or more biologically inactive molecules [s]. Fractional oral availability - ANSWER- The proportion of the drug that reaches the systemic circulation following an oral dose. It has no units, it is a proportion often expressed as a %. What is the clinical relevance of Vd - ANSWER- Allows determination of the amount of drug in the body required to achieve a target concentration and hence the loading dose. What is the primary determinant of maintenance dose rate - ANSWER- Drug clearance What is the clinical relevance of clearance - ANSWER- Drug clearance determines allows the determination of the rate of elimination and hence the maintenance dose rate to achieve a target drug exposure [AUC] for an individual. Vd and Cl are two important parameters. Discuss the variability in renal dysfunction - ANSWER- Clearance is decreased for drugs that are renally cleared unchanged. Metabolised drugs are not affected. Vd - renal disease is associated with smaller Vd for drugs with low protein binding and larger Vd for drugs with high protein binding. Vd and Cl are two important parameters. Discuss the variability in relation to pharmacogenetics - ANSWER- Cl - for drugs metabolised by pathways subject to polymorphisms this is dependent on the particular genotype, which may result in phenotypes including poor metabolisers, extensive metabolisers and ultrametabolisers. Generally no effect is expected for drugs that are renally cleared unchanged. Vd - generally no effect is expected. Vd and Cl are two important parameters. Discuss the variability in relation to obesity - ANSWER- Cl - this is increased in absolut terms (ie unit volume per unit time) but is reduced on a per kg of total body weight basis. Vd - decreased for hydrophilic drugs and increased for lipophilic drugs on a per kg of total body weight basis. What is clearance - ANSWER- A constant relating the rate of elimination to plasma concentration. More specifically for drugs with first order elimination, drug clearance is the capacity of the body to remove the drug from circulation, measured by the volume of plasma from which a substance is completely removed per unit of time. What is the best index of drug exposure - ANSWER- Area under the concentration-time curve [AUC] What are efflux transporters? - ANSWER- Efflux transporters actively transport lipid soluble drugs away from the body What are solute transporters? - ANSWER- Solute transporters move anions and cations in both directions across cell membranes What happens if you decrease function or inhibit efflux transporters - ANSWERDecreased efflux means that more drug is retained. - increased intracellular conc