Basic Principles of Pharm III Flashcards

1
Q

passive transport processes

A

follow a concentration gradient or hydrostatic pressure, don’t require metabolic energy

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2
Q

What variables affect simple diffusion?

A

lipid solubility, size (smaller is better), degree of ionization (nonionized is best)

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3
Q

Facilitated diffusion

A

uses a carrier protein

  • masks characteristics that may impede simple diffusion
  • selective, can be inhibited, can be saturated
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4
Q

filtration

A

driven by hydrostatic pressure

  • drug dissolved in the moving fluid is transported through pores in a membrane or channels between cells
  • drug molecule size is limiting
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5
Q

Active transport processes

A

Use metabolic energy in the form of high energy phosphates such as ATP or electrochemical gradients

  • transport against a concentration gradient
  • rapid, selective, can be inhibited, can be saturated
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6
Q

Active transport

A

uses a carrier

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7
Q

Micropinocytosis

A

Drug is transported in pinched off packets of single layer membrane

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8
Q

Weak electrolyte drugs

A
  • nonionized forms can diffuse, ionized cannot

- weak acids give up a proton, weak bases accept a proton

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9
Q

Henderson Hasselbach Equation

A

pH = pKa + log A-/HA OR

log A-/HA = pH - pKa

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10
Q

Enteral advantages/ disadvantages

A
  • use a portion of GI tract
    Advantages: ease, safety, self-admin, cheap, prolonged absorption –> prolonged effect

Disadvantages: absorption can be too slow, often variable and unpredictable, can be too irritating, drug can be destroyed by gastric acid, enzymes, can be completely metabolized on first pass thru liver, not available for comatose or vomiting pts

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11
Q

Rectal advantages/disadvantages

A

Advantages: useful for infants, comatose, vomiting pts

  • good for smelly or bad tasting drugs
  • good for drugs destroyed in upper GI tract
  • avoids immediate liver metabolism
  • for local action in rectum

Disadvantages: nuisance –> poor compliance, absorption may be erratic or incomplete, possibly irritating to rectum

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12
Q

Sublingual advantages/disadvantages

A

Advantages: bypasses liver when first absorbed
- rapid absorption

Disadvantages: must be soluble in saliva, not too bad tasting, have appropriate pKa for rapid absorption. must be small tablets.

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13
Q

Intravenous pro/con

A

Pros: rapid effect, can watch response and titrate dose, all of dose enters circulation, can use when oral route unavailable, for drugs too irritating when given IM or SC, for drugs in large volumes of fluid, infusion and continuous monitoring, parenteral administration of hypertonic solutions is possible

Cons: cost, skill in administering, danger of infxn, possible anaphylaxis, danger of embolus formation, danger of adverse cardiovascular effects with too fast administration, pain

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14
Q

Intraarterial pro/con

A

Pros: administration of radio-opaque material for visualization of circulatory tree
- high concentration of drug going to local area when desirable

Disadvantages: same as for IV

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15
Q

Intramuscular pro/con

A

Pro: when oral route unavailable, absorption less variable than with oral route, may be less painful than SC, possibility of slowing absorption to prolong effect

Cons: pain, sterile technique, possible local necrosis, lag period before effect onset, accidental IV injection possible, not to be used after anticoagulant admin

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16
Q

Subcutaneous injection pro/con

A

Pro: absorption usually slower than IM, effect more prolonged
- Same general pros as IM

Con: same as IM

17
Q

Intrathecal pro/con

A

Pro: when local effect on CNS is required and other routes are unsatisfactory

Cons: skill, danger of spinal cord injury

18
Q

Topical pro/con

A

Pro: for local action on or under skin, for local action on or under membrane, non-invasive

Con: difficulty of absorption thru skin, danger of excessive absorption thru membranes and systemic toxicity

19
Q

Inhalation pro/con

A

Pro: rapid absorption for systemic action, high concentration for local effect, self-admin possible

Con: possible excessive absorption and systemic toxicity, poor regulation of dosage, irritation of pulmonary

20
Q

Bioavailability

A

The fraction of dose available for biologic action
- usually pertains to oral drug admin where variable absorption or “first pass” effects will decrease the amount of drug that reaches circulation

= AUC oral/ AUC injected x 100

21
Q

Plasma concentration equation

A

(F x dose) = Cp x Vd

where F = fraction absorbed, Cp = plasma conc, Vd = volume of distribution

22
Q

Factors that effect absorption

A

Enteral: form of drug, food in stomach, illness, blood flow
Solution>suspension>capsule>tablet>timed release

Parenteral: blood flow, heat, cold, illness, form of drug (wafer, rods, injection in oil, transcutaneous patch)