1. The pharmacokinetics of nicotine can be approximated with the material balance: dc V = dt k₁n – k₂С – k³C when smokin

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1. The pharmacokinetics of nicotine can be approximated with the material balance: dc V = dt k₁n – k₂С – k³C when smoking; IC C = Co at t = 0 dC V = dt - k₂С – k3С when done smoking; with IC C = C₁ at t = 0 where V 40 1 volume of distribution of nicotine in the body plasma concentration of nicotine ng ml-¹ k₁ 800,000 ng number of cigarettes smoked per hour amount of nicotine absorbed per cigarette rate coefficient for hepatic metabolism rate coefficient for renal clearance k2 25 1h¹ k3 11 1h¯¹ t h time (a) Label each term in the first balance with the letter(s) corresponding to its significance. Some terms may have more than one correct answer; in that case give both appropriate answers. USES C n
A. Accumulation B. Flow in C. Flow out D. Generation E. Consumption F. Growth G. Metabolism H. Recycle I. Mass transfer J. Excretion
(b) Circle each of the following that are true about this model A. Assumes the volume V is well-mixed (instantaneous distribution) B. Assumes zero-order kinetics of nicotine metabolism in the liver C. Assumes steady-state D. Assumes no loss of nicotine through exhaled breath E. Assumes gas-liquid equilibrium partitioning of nicotine in the lung F. Assumes first-order kinetics of nicotine elimination via the urine G. Assumes no generation of nicotine in the body (c) What is the half-life of nicotine in the body after smoking stops? (d) Suppose it is desired to design a transdermal anti-smoking aid patch that will deliver nicotine continuously to the body through the skin. The target blood concentration of nicotine is 12 ng ml-¹. What is the required nicotine delivery rate (in ng h`¹) to achieve this steady concentration? TIP: replace the term in the material balance that is associated with delivery of nicotine from cigarettes with a term for delivery from the patch. (e) The solution to the first differential equation given above is: k3)t` k₁n k₂ + k3 C = -(k₂+ k3)t V -(1-e =^² + ³)²) + C₂e² How long does it take after putting the patch on to reach 10 ng ml-¹? Assume there is no nicotine in the blood initially.