Pharmacology 04 - Pharmacokinetic Principles - Absorption

Front 1

What are the 4 pharmacokinetic processes?

Back 1

1. Absorption, 2. disribution, 3. metabolism, 4. excretion

Front 2

Define: pharmacokinetic processes

Back 2

Action of body on drug

Front 3

CT

Back 3

Target drug concentration in plasma

Front 4

CSS

Back 4

Steady state of target drug concentration in plasma

Front 5

F

Back 5

F = Bioavailability = Fraction(%) of administered drug that reaches the systemic circulation via a given route(IV route F =1 then measure everything against this)

Front 6

Equation for amt of drug reaching systemic circulation?

Back 6

F * Dose

Front 7

Is there an absorption component in IV dose?

Back 7

No b/c ur injecting it right into the blood thus F=1 (100% fraction)

Front 8

What is the first pass effect?

Back 8

Amount of drug that is broken down when drug is absorbed thru gut and remaining (stuff that isnt broken down) that passes thru the liver

Front 9

What is the rate dependent upon for intramuscular(IM) injections

Back 9

Rate dependent on drug form and solubility (lipid/water)

Front 10

What is the MOA of prolonged release medication?

Back 10

Rate of PO absorption depends upon drug rates of dissolution in GI tract (ie how fast it gets absorbed) -> results in slow, uniform absorption of drug for 8 hrs or longer; the less frequent adminstration needed -> ↑ patient compliance

Front 11

What are the advantages of a prolonged release medication?

Back 11

1. Less frequent administration, 2. therapeutic effect overnight, 3. less incidence/severity of side effects, 3. patient compliance

Front 12

Inhalation drug administration advantages

Back 12

1. Drug delivered to target organ, 2. lungs = large surface area -> good absorption, rapid onset, short duration;

Front 13

Topical drug administration advantage?

Back 13

Localized site of action thru intact skin; ie nicotine patches

Front 14

Define: parenteral drug administration

Back 14

Route other then through GI tract (usually injection)

Front 15

What are the advantages of IV + IA drug administration?

Back 15

IV (intravenous) - no absorption needed + dose titration of anesthesia; IA(intra-arterial) - used for anti-cancer agents + diagnostic uses

Front 16

Buccal + sub-lingual advantages?

Back 16

are directly absorbed into the systemic circulation -> fast + bypasses first pass effect cuz it doesn't go thru the liver first

Front 17

Rectal advantage? Disadvantage?

Back 17

Good if patient is vomiting or unconscious - 50% of drug absorbed by rectum will bypass liver. Disadvantage - irregular absorption, rectal irritation

Front 18

What is the limitation of enteral route of drug administration?

Back 18

Drug inactivated by digestive enzymes; incomplete clinical conditions (vomiting, unconsciousness), blood flow, surface area; drugs that are unable to be absorbed thru GI tract

Front 19

How do u calculate new dosage(utilizing bioavailability)?

Back 19

(Dose of new form = dose * F of current form)/(F of new dosage form)

Front 20

36 yo patient is currently receiving 2 mg daily of erythromycin IV for his whooping cough. He is being discharged and will switch to erythromycin PO. About how much will he have to take by mouth to equal his current IV dose? F=0.35

Back 20

(1 * 2)/.35 = 5.7143 ~ 6mg

Front 21

What is the first pass effect?

Back 21

Amount of drug that is broken down when drug is absorbed thru gut and remaining (stuff that isnt broken down) that passes thru the liver

Front 22

Per os(PO)

Back 22

Taken by mouth

Front 23

Is there an absorption component in IV dose?

Back 23

No b/c ur injecting it right into the blood thus F=1 (100% fraction)

Front 24

How to calculate bioavailability using a graph?

Back 24

Area under curve Oral dose/ area under curve IV dose = Fraction %