Pharmacokinetics 2

Question 1

intravenous injection: what? speed?

Answer 1

drug injected into vein. rapid distribution and onset of action.

Question 2

intravenous injection: method requires? should not cause? cons?

Answer 2

skill to find vein and special drug solutions that are sterile. shouldn’t cause direct damage to veins or pain. greater risk or overall costs.

Question 3

intravenous injection: drug given in what two ways?

Answer 3

rapid as a bolus = push. continuous infusion = drip.

Question 4

subcutaneous injection: what? speed?

Answer 4

drug injected below skin close to capillaries. absorption speed fairly rapid but depends on blood flow, not really faster than oral route.

Question 5

subcutaneous injection: how to limit absorption ? have to limit volume? common route for?

Answer 5

addition of vasoconstrictors helps prolong local action. limit volume to reduce swelling and pain. insulin, heparin, allergy tests

Question 6

intramuscular route: drug injected where? volume? __ route prevents?

Answer 6

into skeletal muscle; can accommodate larger volume. Z route prevents leakage

Question 7

intramuscular injection: speed? what affects rate?

Answer 7

may not be faster than oral. muscle activity and blood flow affects rate

Question 8

intramuscular injection: poor route for?

Answer 8

obese patients because site may be fatty

Question 9

drug administration by inhalation: speed? why?

Answer 9

drug absorbed rapidly through lungs: high surface area and high blood flow, rapid distribution (lung to heart to body)

Question 10

inhalation: common route for?

Answer 10

general anesthetics, nicotine, cocaine, poison gases

Question 11

inhalation: drug in what form?

Answer 11

gas, vapor or fine powder.

Question 12

drug administration via skin: aka? most chemicals crossing skin?

Answer 12

topical; through or across layers of dermis but most chemicals won’t cross intact skin

Question 13

common drugs in transdermal patches. 3 pros?

Answer 13

estrogen, nicotine, scopolamine, nitroglycerin, fentanyl. easy, continuous and stable.

Question 14

drugs distribute evenly? redistribution effects?

Answer 14

rarely distribute evenly in body: redistribution may limit duration of action, may prolong time drug remains in the body

Question 15

drugs partition according to? (4)

Answer 15

special membrane barriers, solubility of drug in fat/tissue. degree of ionization of drug. plasma protein binding.

Question 16

special membrane barriers: 3 examples

Answer 16

walls of capillary vessels. blood brain barrier. placental barrier.

Question 17

placental barrier: is it a good barrier?

Answer 17

not a major barrier to drugs. easy transfer by passive diffusion. fat soluble drugs cross easily

Question 18

drug ionization: most drugs are? exist in what forms? depending on?

Answer 18

weak acids/bases. exist in both charged and uncharged forms depending on drug pKa and pH of environment.

Question 19

Ka? pKa?

Answer 19

dissociation constant. pKa: pH at which ratio of ionized:unionized drug is equal

Question 20

Henderson-Hasselbalch equation

Answer 20

pH = pK + log [A-]/[AH]