Help please in computation

[chertian]

Hi. I need help with computations. I got the sample problems at CPR chapter 6.

Problem 1- A new cephalosporin antibiotic was given at 5mg/kg by a single IV bolus injection to a 58yr old man who weighs 75kg. The antibiotic follows a pharmacokinetics of one-compartment model & has an elimination half life of 2hrs. The apparent volume of distribution is 0.28L/kg and the drug is 35% bound to plasma proteins.

1. What is the initial plasma drug concentration? (Cp) ans: 1339mg/L
2. What is the Cp at 8hr after the dose?
3. How much drug remains in the patient's body (Db) 8 hr after the dose?
4. How long after the dose is exactly 75% of drug eliminated from the patient's body?


Problem 2 - A 35 yr old man who weighs 70kg & has normal renal function needs an IV infusion of antibiotic carbenicillin. The desired steady-state plasma concentration is 15mg/dL. The physician want the antibiotic to be infused into the patient for 10hrs. CArbenicillin has an elimination half-life of 1 hr & apparent volume of distribution(Vd) of 9L in this patient.

1. Assuming that no loading dose was given, what rate of IV infusion is recommended for this patient?
2. Assuming that no loading dose IV dose was given, how long after the initiation of the IV infusion would the plasma drug concenration reach 95% of the theoretic steady-state drug concentration?
3. Waht is the recommended loading dose?
4. What is the total body clearance rate for the carbenicillin in this patient?
5. If the patient's renal clearance for carbenicillin is 85 mL/min, what is the hepatic clearance in this patient?
6. To infuse the antibiotic as solution containing 10g drug in 500 mL 5% dextrose, how many milliliters per hour of the solution would be infused into the patient?

Thanks a lot! Im really having a hard time when it comes to computation part.