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Pharm > Pharmacotherapy II > Flashcards

Pharmacotherapy II Flashcards

1
Q

Pharmacokinetics

A

What the body does to the drug (absorption, distribution, metabolism, excretion)

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2
Q

Pharmacodynamics

A

What the drug does to the body

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3
Q

Therapeutic window

A

Range of blood drug concentration that yields a sufficient therapeutic response (without a toxic reaction)

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4
Q

Absorption

A

How administered drugs are absorbed into body (depends on route of administration)
Many factors including route of admin and bioavailability

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5
Q

Distribution

A

How drugs are distributed to the site of action

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6
Q

Metabolism

A

Biotransformation of the drug from active to inactive form (to prepare for elimination)

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7
Q

Bioavailability

A

Rate and extent a drug is absorbed from a substance (tablet, capsule, etc.) and is available at site of action

Fraction or percentage of an administered dose of drug that reaches the circulation in its unmetabolized form)

First pass effect (hepatic metabolism)
Pro-drugs (active metabolites)
Drug formulation (immediate release vs. extended release)
GI motility
Blood flow

Blood flow and ability of drug to pass through membranes or barriers in the body affect bioavailability, but may also be discussed in the distribution phase of pharmacokinetics

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8
Q

First pass effect

A

Drugs are metabolized by liver before passing into circulation

After absorption into alimentary canal, drugs go directly to the liver through the portal vein

Hepatic enzymes metabolize the drug, reducing the amount of active drug in the bloodstream

Drugs administered orally are subject to the first pass effect

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9
Q

Pro-Drugs

A

Drugs that have no biologic activity itself, but once metabolized in the liver it becomes an active metabolite

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10
Q

Immediate release

A

Delivered to GI tract quickly for quick onset of action
Absorbs well in acidic environment

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11
Q

Extended release

A

Extends activity of drugs in the body to level out high peaks and low troughs of concentrations to achieve a more consistent level in the blood

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12
Q

Enteric coating

A

Slows drug to be dissolved in intestines rather than stomach
Intestines have higher pH
Helps preserve gastric mucosa

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13
Q

Gastric emptying

A

Higher gastric emptying rate hastens absorption and bioavailability in the intestines
High fat meals and solid foods may delay drugs initial delivery to intestinal absorption surfaces

Gastric emptying will contribute to absorption and bioavailability

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14
Q

Decreased intestinal motility

A

Slowed intestinal peristalsis leads to greater absorption and bioavailability

Agents that slow intestinal motility (anticholinergic) will prolong contact time with intestinal surfaces

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15
Q

Increased intestinal motility

A

Increases peristalsis leads to less absorption and bioavailability

Agents which increase motility (laxative) could shorten contact time with intestinal surfaces and therefore decrease drug absorption

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16
Q

Blood flow

A

Absorption and distribution impacted by blood flow based on adequate perfusion

Gut and intestinal perfusion important for absorption

Hypo and hyperperfusion may affect bloodflow and delivery of drug

More vascular areas are better perfused (IM vs. subQ)

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17
Q

Absorption routes of administration

A

Enteral (absorbed through GI tract)

Oral - first past effect

Sublingual, buccal, and rectal bypass the first pass effect and tend to be more potent = quicker onset of action

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18
Q

Parenteral

A

All routes of admin not involving GI tract

IV - rapid access to circulation, immediate serum levels no first pass effect

IM - Slower onset than IV, no first pass effect, absorption required

SubQ - Slower than IM, no first pass effect, absorption required

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19
Q

Inhalation

A

Drug is gaseous or sprayable and delivered directly into lung, no first pass effect, high bioavailability

20
Q

Topical delivery

A

Applied to skin surface or mucus membrane, local absorption does not cross dermis

21
Q

Transdermal

A

Systemic delivery of drug through skin over time, intended for steady delivery (nicotine patch)

22
Q

Distribution

A

Distribution of absorbed drug depends on blood flow to area, lipid or water solubility, and protein binding

23
Q

Protein binding

A

After absorption, a drug that may circulate through the body unbound (free drug) or bound to carrier proteins. Extent of drug binding to carrier proteins depend on affinity of drug for that protein and concentrations of both drug and protein

24
Q

Lipid and water solubility

A

How drug gets into cell. Biologic membranes act as barriers, blocking or permitting the passage of various substances

Cell membrane allows most hydrophobic compounds to pass through readily, hydrophilic. substances and ionized substances have a harder time passing through

25
Q

Passive diffusion

A

Molecules move from one side of barrier to another without expending energy (high to low)

26
Q

Facilitated diffusion

A

Carrier proteins utilized to transport larger molecules from area of higher concentration to lower

27
Q

Active transport

A

Requires ATP (energy), molecules may move from lower to higher area of concentration

28
Q

Metabolism

A

Function of body to change substances into water soluble forms that will more readily be excreted. Beginning of process of elimination

Liver primarily performs the metabolic functions of body, kidney and intestines also take part

29
Q

Phase 1 metabolism

A

Enzymatic process involves oxidation and reduction

Drug changed to form a more polar or water soluble compound

Hydrolysis

30
Q

Phase 2 metabolism

A

Involves adding conjugate to parent drug or phase-1 metabolized drug to further increase water solubility

31
Q

Cytochrome P-450 System (CYP450)

A

CYP composed to superfamilies of more than 100 enzymes

Three families (about 15 total enzymes) are responsible for drug metabolism in about 90% of cases

Drugs may be a substrate, inducer, or inhibitor of CYP450 system

32
Q

Inducer

A

Stimulates production of enzymes which increases amount of enzymes available for metabolism (phenytoin, rifampin, St John’s Wort)

33
Q

Inhibitor

A

Inhibits production of CYP enzymes, decreasing metabolism of drugs and increasing circulating levels (grapefruit juice, azoles, protease inhibitors)

34
Q

Elimination/Excretion

A

Primary route of excretion through kidneys

Important to know renal function (GFR) to help dose drugs

Other excretory organs (Lower GI tract - feces, lungs - exhalation, and skin - perspiration)

35
Q

Half Life (t 1/2)

A

Time required for 50% of drug to be eliminated from body

If t 1/2 is 10 hours then each 10 hours 50% of what is remaining will be eliminated

Drug is considered fully cleared after 4 to 5 half lives of drug

Important to consider when prescribing multiple classes of drugs

36
Q

Factors interfering with elimination

A

Renal failure - increases half life, need to downward dose adjustment

Hepatic disease - Impacts pro drugs and CYP450 enzymes, increases half life

Exercise regularly vs. intermittently - impacts blood flow, GI motility, body temperature

37
Q

Pharmacodynamics

A

What the drug does to the body

Set of processes that drugs produce specific biochemical or physiologic changes in body

Impacted by:
- Receptor abundance (age related)
- Receptor affinity (age related)
- Post receptor changes and sensitivities

38
Q

Agonists

A

Creates a response

Dose dependent

Dependent on receptor sensitivity

Full agonist: 100% of desired effect

Partial agonist creates a partial response

39
Q

Antagonist

A

Creates no biological response

Blocks receptors from agonists

Compete for receptor sites

Noncompetitive sites

40
Q

Autonomic nervous system

A

Involuntary functions: Thermoregulation, vascular contractility, heart and respiratory rates, digestion

Sympathetic vs. Parasympathetic

41
Q

Somatic nervous system

A

Voluntary functions, movement, speech

42
Q

Sympathetic

A

Fight or flight

Norepinephrine neurotransmitter

Agonist vs. antagonist

Alpha1 receptors (smooth muscle effects)

Alpha2 receptors (brain, stem, SC, and eye)

Beta1 receptors (myocardium) = 1 heart

Beta2 receptors (lung) = 2 lungs

43
Q

Parasympathetic

A

Cholinergic, muscarinic receptors

Acetylcholine (ACH)

Agonists prolong ACH activity, cause contractions, increased secretions

Antagonists = anticholinergics - block the effect of ACH. Urinary retention, xerostomia, increased HR

44
Q

ED50

A

Drug dose that results in a therapeutic effect of 50% recipients

45
Q

LD50

A

Drug dose that is lethal of 50% of recipients

46
Q

Potency

A

Amount of drug needed to produce a response

47
Q

Therapeutic index

A

TI = (LD50/ED50)

If a drug is lethal to 50% at 100mg but effective to 50% of recipients at 25mg
TI = 100/25 = 4mg is considered likely a safe dose without side effects

If a drug is lethal to 50% of recipients at 50mg but effective to 50% of recipients at 2mg
TI = 50/2 = 25mg is considered likely a safe dose without side effects

Pharm (2 decks)

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