Basic Principles III

Question 1

passive processes

Answer 1

simple diffusion, facilitated diffusion, filtration

Question 2

active processes

Answer 2

active transport, micropinocytosis

Question 3

weak electrolyte drugs

Answer 3

ionized forms do not diffuse, non-ionized forms diffuse and are lipid soluble. Follow the concentration gradient

Question 4

weak acid drugs

Answer 4

will be in HA form in the stomach fluid (low pH), but when they diffuse to plasma (higher pH), will mainly be in H + A form

Question 5

weak base drugs

Answer 5

will be in H + B form in stomach fluid (low pH), but when they diffuse to plasma, they will mainly be in the HB form

Question 6

enteral administration

Answer 6

uses a portion of the GI tract

Question 7

parenteral administration

Answer 7

does not use the GI tract

Question 8

considerations for routes of administeration

Answer 8

planned use of medication, clinical setting (acute vs chronic), rapidity of onset of desired action, specific target organ that drug is intended to reach

Question 9

oral advantages

Answer 9

easy, safe, self administered, cheap, prolonged absorption causes prolonged effect

Question 10

oral disadvantages

Answer 10

may be too slow, unpredictable, and variable. May be too irritating or destroyed by gastric acids. May be completely metabolized on first pass through liver. Not available for comatose or vomiting patients

Question 11

rectal advantages

Answer 11

useful for infants, coma, vomiting. Useful for bad tasting drugs. Useful for drugs destroyed in upper GI tract. Avoids liver. For local action in rectum

Question 12

rectal disad

Answer 12

poor compliance. Absorption may be erratic. Possibility of rectal irritation

Question 13

sublingual advantages

Answer 13

bypasses liver when first absorbed. Rapid absorption

Question 14

sublingial diasadvan

Answer 14

must be soluble in saliva, not distasteful, have appropriate pKa for rapid absorption. Must be small tablets.

Question 15

IV advantages

Answer 15

rapid effect, can watch response and titrate dose, all dose enters blood, good for when you cant do oral, good for irritating drugs or large volumes of drugs. Allows hypertonic solution to be administered

Question 16

IV disadvan

Answer 16

cost, skill in administration, danger of infection, embolus formation, anaphylactic rxn, adverse cardiovascular effects if given too fast, painful

Question 17

intraarterial advantages

Answer 17

administration of radio-opaque material for visualization of circulatory tree. High concentration of drug going to local area when desirable.

Question 18

intraatertial disadvan

Answer 18

cost, skill in administration, danger of infection, embolus formation, anaphylactic rxn, adverse cardiovascular effects if given too fast, painful

Question 19

intramuscular advantages

Answer 19

when oral isnt avail, may be less variable absorption, may be less painful than subcutaneous, more rapid absorption than subcutaneous, possiblity of slowing absorption to prolong effect

Question 20

intramuscular disadvan

Answer 20

pain, sterile, posible local necrosis, lag period before onset, accidental injection in vein possible, not to be used after anticoag

Question 21

subcutaneous advantages

Answer 21

absorption usually slower than intramuscular, more prolonged effect

Question 22

subcutaneous disadvan

Answer 22

pain, sterile, posible local necrosis, lag period before onset, accidental injection in vein possible, not to be used after anticoag

Question 23

intrathecal advantages

Answer 23

when local effect on CNS required and other routes are unsatisfactory

Question 24

intrathecal disadvan

Answer 24

skill needed, danger of spinal cord injury

Question 25

topical advantages

Answer 25

for local action on or under skin/membrane. Non invasive

Question 26

topical disadvan

Answer 26

difficulty of absorption through skin. Danger of excessive absorption through membranes and systemic toxicity

Question 27

inhalation advantages

Answer 27

rapid absorption for systemic effect. High concentration attainable for local effect. Self administration possible

Question 28

inhalation disadvan

Answer 28

possible excessive absorption and systemic toxicity. Poor regulation of dosage, irritation of pulmonary tract

Question 29

bioavailability

Answer 29

fraction of dose available for biologic action. Measured by the area under the curve for the oral dose form vs. the IV dose form

Question 30

limiting step for oral drugs

Answer 30

usually dissolution

Question 31

factors affecting absorption in enteral drugs

Answer 31

form of drug, food in stomach, illness, blood flow

Question 32

factors affecting absorption in parenteral drugs

Answer 32

blood flow, head, cold, illness. Form of drug