Pharmacology

Question 1

What’s the pH of plasma?

How does difference of pH and pKa affects solubility in plasma (water solubility)?

Answer 1

around 7.4
Weaker acids/alkali with greater difference between pKA and pH generally more water soluble than those of stronger acids/alkali
>2.0 = 99% soluble ; 0 = 50% soluble

Question 2

What is drug clearance? Formula?

Answer 2

Drug clearance = volume of plasma cleared of drug per unit of time
CL = rate of drug elimination/plasma concentration
CL = 0.7 x Vd / T1/2

CL via urine = (drug concentration in urine x urine output volume)/ plasma concentration

Question 3

What factor affects the time to reach steady state of drugs? (rate in = rate out)

Answer 3

half life of drugs ONLY

(rate of infusion, size of dose, frequency of administration does not affect the time to reach steady state but affects plasma level)

Question 4

State 3 processes of Phase 1 metabolism

Answer 4

Phase 1: oxidation, reduction, hydrolysis (alcohol, MAO)

Question 5

Formula of apparent Volume of distribution (Vd)

Answer 5

Vd = dosage / plasma concentration at time 0

Question 6

What does drugs with zero-order elimination rate?Name 3 examples

Answer 6

Rate of elimination NOT AFFECTED by drug plasma concentration. No fixed half life.
PEA= phenytoin,ethanol, aspirin

Question 7

Formula of infusion dose

Answer 7

Target plasma drug concentration x CL x dosage time interval / bioavailability

Question 8

Formula of loading dose aka bolus dose

Answer 8

Target plasma drug concentration x Vd / bioavailability

Question 9

Formula for half life

Answer 9

0.7 x Vd / CL

Question 10

Drug causing drug induced lupus

Answer 10

Makes My HIPS Extremely Painful

Methyldopa, Minocycline, Hydralazine, Isoniazid, P, Sulfa drugs, Etanercept, Procainamide

Question 11

Explain the meaning of each of the following drug effect modifications and give an example of each:

1. Additive
2. Permissive
3. Synegistic
4. Potentiation
5. Antagonistic
6. Tachyphylactic

Answer 11

1. 1+1=2 aspirin + acetaminophen
2. B is NOT totally useless and is required for C to have full effects: cortisol + catecholamines
3. 1+1 >2 clopidogrel +aspirin
4. B totally useless but is required for C to have full effects: carbidopa + levodopa
5. 1+1<2 methanol + ethanol
6. similar to toleranceL hydralazine, nitrate, niacine, phenylephrine