## Drug dosing

You have a 1mL ampule of a drug with a stock concentration of 400µg/mL. You need to administer 120µg of the drug. The volume (in mL) of the stock preparation you would administer is = Answer mL (provide a numerical answer)

Application of BioavailabilityBased on the bioavaiability of each drug, select the closest equivalent oral dose for each of the following opioid analgesics:
MorphineIV dose = 5 mgfh = 0.4 fg = 0.8Equivalent oral dose:   blank mgCodeineIV dose = 50 mgfh = 0.5fg = 1.0Equivalent oral dose:   blank mg
TramadolIV dose = 100 mgfh = 0.9 fg = 0.9Equivalent oral dose:   blank mg
Which drug has the highest bioavailability?   blank Options:            100 – 50 – 110 – 6 – 15 –Tramadol  – 90  – 190  –   Morphine   250  120   Codeine    20

Calculating Volume of DistributionDrug A has the following phamacokinetic parameters:Hepatic clearance (CLH): 25L/hrRenal Clearance (CLR): 15L/lrhalf life (t1/2): 3hrCalculate the volume of distribution (VD) for this drug (Provide answer in liters (L) as a whole number)Answer:

Factors that alter drug distributionDrug B is a highly protein bound, lipophilic drug. Determine the impact of the following scenarios on the volume of distribution of Drug B:Scenario 1: Administering Drug B to a severely hypoalbumanaemic patient: Choose…Decrease VdNo effect on VdIncrease VdScenario 2: Co-administering a drug that increases the absorption of Drug B: Choose…Decrease VdNo effect on VdIncrease VdScenario 3: Co-administering a drug that out competes Drug B for binding to albumin: Choose…Decrease VdNo effect on VdIncrease Vd Scenario 4: Co-administering a drug that decreases the hepatic metabolism of Drug B: Choose…Decrease VdNo effect on VdIncrease VdHint: in considering the impact of each scenario, consider the the factors that influence drug distribution and whether the scenario will alter one of these factors.

Drug Metabolism ReactionsIdentify the enzyme family involved in the following metabolic reaction: Select one:a. UDP-Glucuronosyltransferaseb. N-Alkyltransferasec. Cytochrome P450d. Flavin Mono Oxygenase
Renal ExtractionActive secretion contributes positively to renal clearance by:Select one:a. Actively pumping bound and unbound drug into the nephron through the Glomerulusb. Actively pumping bound and unbound drug into the nephron through the Proximal Tubulec. Actively pumping only unbound drug into the nephron through the Glomerulusd. Actively pumping only unbound drug into the nephron through the Proximal Tubule

Determinants of EliminationDrug C has the following phamacokinetic parameters:Renal Clearance: 2.5L/hrFraction Unbound in Blood: 0.9Fraction Excreted unchanged in Urine: 1.0Assuming a glomerular filtration rate of 7.2L/hr (for a healthy individual), which processes MUST be involved in the elimination of Drug C?Select one:a. Filtration and Reabsorptionb. Filtration and Secretionc. Metabolism and Secretiond. Filtration and Metabolism

IV Infusion RateYou are looking after a patient that your senior partner has suggested should receive an infusion of an opioid analgesic. In making your decision about how to manage the patient you consult a general drug information resource that contains the following phamacokinetic information regarding the drug:Bioavailability (F): 50 % Urinary excretion (fe): 0.08Fraction unbound in plasma (fu): 0.16Systemic Clearance (CLs): 60 L/hrVolume of Distribution (VD): 320 LHalf life (t1/2): 3.7 hrsBased on this information, calculate the intravenous infusion rate (in µg/hr) that will be required to maintain a steady-state blood concentration of 15 µg/L:Answer:

Relationship between clearance, volume of Distribution and half life for paramedic drugsCalculate the missing numbers to complete the table. (All answers must be rounded to the nearest whole number)Drug CL(L/h) V(L) (t½) (Hr)morphine (example) 80 230 2midazolam 28 77 Answerfexofenadine 39.5 Answer 14amiodarone 8 4620 Answernaloxone Answer 140 1.5diazepam 1.4 Answer 40benzylpenicillin Answer 131 3.5
Application of Half-lifeYou attend a call to a patient who is unwell due to an adverse drug reaction resulting from the patient taking an excessive dose of one of their regular medications. You consult a drug information resource and find out the following information about the drug:Systemic clearance (CLS): 10 L/hrVolume of distribution (Vd): 173 hrTarget plasma concentration range: 80 to 160 mg/LPatients current plasma concentration: 600 mg/LBased on this information, how long (in hours) will it take for the patient’s plasma concentration to return to within the target range?

Metabolic Drug InteractionsDrug D has the following phamacokinetic parameters:Systemic Clearance: 80L/hrFraction Unbound in Blood: 0.5Fraction Excreted unchanged in Urine: 0.02Determine the impact of similtaneously administering a drug that activates the enzymes involved in the metabolism of Drug D on the following pharmacokinetic parameters:Bioavailability: Choose…DecreasedIncreasedEssentially UnchangedSystemic Clearance: Choose…DecreasedEssentially UnchangedIncreasedHalf-life: Choose…IncreasedEssentially UnchangedDecreased

Metabolic Drug InteractionsDrug E has the following phamacokinetic parameters:Systemic Clearance: 3L/hrFraction Unbound in Blood: 0.9Fraction Excreted unchanged in Urine: 0.02Determine the impact of similtaneously administering a drug that activates the enzymes involved in the metabolism of Drug E on the following pharmacokinetic parameters:Bioavailability: Choose…DecreasedIncreasedEssentially UnchangedSystemic Clearance: Choose…DecreasedEssentially UnchangedIncreasedHalf-life: Choose…IncreasedDecreasedEssentially Unchanged

Systemic Clearance Extended CalculationA pharmaceutical company is developing a new drug ‘FCP-17’ and has just determined the following pharmacokinetic parameters from a Phase I human study:Fraction unbound (fu): 0.5Clearance by active secretion (CLsec): 5.4L/hrFraction reabsorbed (FR): 0.2Hepatic Extraction Ratio (EH): 0.1 Question:Showing all working out, and stating all assumptions, Calculate the total SYSTEMIC CLEARANCE for ‘FCP-17’.

inter-Individual VariabilityA pharmaceutical company has convinced your paramedic service to add their new orally administered opioid analgesic ‘fucpoaphine’ to their formulary. Fucpoaphine requires hepatic activation in order to elicit an analgesic effect. Studies in healthy volunteers have demonstrated that fucpoaphine is rapidly activated (within 2minutes) following oral administration and that the sole enzyme involved in the activation of fucpoaphine is CYP2C19. Questions:a) Select ONE specific factor (environmental, genetic or physiological) that may contribute to inter-individual variability in the activation of fucpoaphine, and explain the potential consequences of this variability in terms of treatment response and tolerability. (200 words)b) Identify a strategy to account for variability in fucpoaphine activation that can be used in a pre-hospital situation and briefly explain how this strategy could be used to optimise treatment response and tolerability. (100 words)