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Pharmacology > FA.Pharm.Pharmacodynamics > Flashcards

FA.Pharm.Pharmacodynamics Flashcards

1
Q

Km is the…

A

Affinity of the enzyme for the substrate

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2
Q

Vmax is directly proportional to the ….

A

(aka efficiency) is directly proportional to the enzyme concentration

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3
Q

How does a \/ Km effect affinity?

A

/\ affinity (/\ potency)

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4
Q

Lineweaver Burke plot:

/\ y-intercept –> effect on Vmax

A

\/ Vmax

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5
Q

Fill in the blank:

On a lineweaver burke plot, the further to the right the x-intercept, the ______ the Km and the ______ the affinity

A

Greater, Lower

b/c Km and Affinity are indirectly proportional

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6
Q

Lineweaver Burke:

Competive inhibitors do/do not cross each other?

A

DO.

Competitive inhibitors cross competitively, while noncompetitive inhibitors do not cross.

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7
Q

Competitive Inhibitors:

Resemble substrate?
Overcome by /\ [s]?
Bind active site?
Effect on Vmax?
Effect on Km?
Pharmacodynamics?
A 
Resemble substrate? Yes
Overcome by /\ [s]?  Yes
Bind active site?  Yes
Effect on Vmax?  No change
Effect on Km?  /\
Pharmacodynamics? \/ potency
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8
Q

Noncompetitive inhibitors:

Resemble substrate?
Overcome by /\ [s]?
Bind active site?
Effect on Vmax?
Effect on Km?
Pharmacodynamics?
A 
Resemble substrate?  No
Overcome by /\ [s]?  No
Bind active site?  No
Effect on Vmax?  \/
Effect on Km?  No change
Pharmacodynamics? \/ Efficacy
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9
Q

Pharmacokinetics:

Volume of distribution relates the ______ to the ______.

A

Relates the AMOUNT of the drug to the PLASMA CONCENTRATION.

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10
Q

What disease processes can alter the Vd of plasma-protein bound drugs?

A

Liver and Kidney disease ( \/ protein binding, /\ Vd )

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11
Q

Vd formula

A

Vd= (amount of drug in body) / (plasma drug concentration)

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12
Q

Drugs with LOW Vd (4-8 L) distribute in ______. These are examples of (small / large) or (charged / uncharged).

A

Large or charged drugs will distribute primarily in the BLOOD, .: these have a LOW Vd.

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13
Q

Medium Vd: distributes in the _________ or _________;

General description of this class?

A

Medium Vd distribute in EXTRACELLULAR SPACE or BODY WATER.

These are SMALL hydroPHILIC molecules that do NOT bind plasma proteins

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14
Q

High Vd (> body weight): distribute to ______?

General description?

A

Distribute to ALL body tissues

SMALL lipoPHILIC that STRONGLY bind to EXTRAvascular proteins

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15
Q

Clearence (CL): relates the _______ to the ______

A

CL relates the RATE of ELIMINATION to the PLASMA CONCENTRATION

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16
Q

CL formula

A

CL = (Rate of elimination of drug [vol. cleared/ time]) / (Plasma Drug Concentration)

= Vd * Ke (elimination constant)

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17
Q

Half-life (t 1/2): The time required to…

Is a property of what kind of zero/first order elim?

A

decrease the drug in the body by 50% during constant infusion.

Property of first order elimination

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18
Q

A drug infused at a constant rate (IV) takes ____ half lives to reach steady state?

A

4-5 half lives

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19
Q

of half lives –> concentration:

1–>
2–>
3–>
4–>

A

1 –> 50%
2 –> 75%
3 –> 87.5%
4 –> 93.75%

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20
Q

Formula for Half Life

A

Half Life = (0.7 * Vd) / CL

21
Q

Bioavailability (F) is the…

A

fraction of administered drug that reaches circulation (F for Fraction)

22
Q

Bioavailibility (F) for:

IV –>

Oral –>

A

IV –> 100%

Oral –> % that survices first pass thru liver or gut

23
Q

Loading dose calculation

A

Loading dose = Cp * Vd / F

Cp –> target plasma concentration

24
Q

Maintenance dose calculation

A

Maintenance dose = Cp * CL / F

25
Q

Frequency [is / is not] affected by time to steady state but [is / is not] affected by half-life.

A

Frequency IS NOT affected by time to steady state but IS affected by half-life.

26
Q

How does renal or liver dz change the maintenance or the loading dose?

A

\/ maintenance dose

NO CHANGE for the loading dose

27
Q

In Zero-order elim. the ____ is constant regardless of the Cp.

A

rate of elimination is constant regardless of Cp.

Cp \/ LINEARLY with time

28
Q

Examples of zero-order elimination drugs

A

Phenytoin, Ethanol, Aspirin

¶ PEA: a pea is round, like the “0” in zero-order

29
Q

First order elimination: a constant _____ eliminated per unit of time.

A

a constant FRACTION eliminated per unit of time

Cp \/ exponentially with time

30
Q

[true / false ] ionized drugs are trapped in urine

A

True.

Weak acids get trapped in basic urine

Weak bases are trapped in acidic urine

31
Q

Weak acid drugs (name 3) get trapped in [basic / acidic] urine?

Tx:

A

Phenobarbital, Methotrexate, Aspirin

Trapped in basic environments

Tx: BICARBONATE

RCOOH RCOO- + H+

32
Q

Weak bases (1 example) are trapped in _____ environments.

Tx overdose with ____

Generalized dissociation formula

A

Trapped in ACIDIC environments

Tx overdose with AMMONIUM CHLORIDE

RNH3+ <=> RNH2 + H+

33
Q

Phase 1 metabolism occurs via the ______, and involves _____, _____, and _____ of drugs. This yields [polar / nonpolar], [water soluble / NON water soluble] metabolites, which are often [active / inactive]

A

Phase 1 metabolism occurs via the CYTOCHROME P450 system, and involves REDUCTION, OXIDATION, and HYDROLYSIS of drugs. This yields POLAR, WATER-SOLUBLE metabolites, which are often ACTIVE.

34
Q

Phase 2 metabolism:

Modifies drugs in 3 ways, _____,_____, and _____.

Usually yields [polar / nonpolar], [active / inactive] metabolites which are subsequently _____ by the _____.

A

Phase 2 metabolism:

Modifies drugs in 3 ways, Glucuronidation, Acetylation, and Sulfation.

Usually yields very POLAR, INACTIVE metabolites which are subsequently EXCRETED by the KIDNEY.

35
Q

Phase 2 metabolism mnemonic: GAS

A

Glucuronidation
Acetylation
Sulfation

¶ Geriatric patients lose phase I first, therefore
¶ Geriatric patients have GAS (phase 2)

36
Q

Patients who are slow acetylators have [greater / lesser] side fx from certain drugs.

Why?

Give 1 drug as an example.

A

Patients who are slow acetylators have GREATER side fx from certain drugs.

Why? Because of the \/ rate of metabolism

Ex: Isoniazid (INH) p. 212

37
Q

Efficacy is defined as the…

A

Efficacy is defined as the MAXIMAL EFFECT a drug can produce.

Analogous to Vmax

38
Q

Name four broad drug classes that have HIGH efficacy

A
  1. Analgesics
  2. Antibiotics
  3. Antihistamines
  4. Decongestants
39
Q

Potency is defined as the…

A

Potency is defined as the AMOUNT of DRUG needed for a GIVEN EFFECT

/\ Potency –> /\ Affinity for receptor –> \/ Km

40
Q

Name 3 broad drug classes with HIGH potency.

A
  1. Chemotherapeutic drugs
  2. Antihypertensive (blood pressure) drugs
  3. Antilipid (cholesterol) drugs
41
Q

Competitive agonists [right / left] shift the ∫ curve?

[increase / decrease] the [efficacy / potency]?

A

Competitive agonists right shift the ∫ curve

DECREASE the POTENCY

Thus, more drug needed to reach same effect.

∫ –> ∫

42
Q

Noncompetitive antagonists [increase / decrease] the [efficacy / potency]?

How does this effect the ∫ curve?

A

Noncompetitive antagonists DECREASE the EFFICACY.

\/ the height of the ∫ (\/ the Vmax)

43
Q

Pharmacodynamics

Partial agonists act at same site as full agonist, but with [increased / decreased] maximal effect.

Efficacy is [increased / decreased]?

Potency is [increased / decreased]?

A

Partial agonists act at same site as full agonist, but with DECREASED maximal effect.

Efficacy is DECREASED.

Potency can be increased or decreased. It is a different variable.

44
Q

Diazepam + Flumazenil on GABA receptors

A

Example of Competitive antagonist.

Flumazenil is the Tx for a benzo OD.

45
Q

Example of a Noncompetitive antagonist of Norepinephrine and receptor

A

Norepinephrine + phenoxybenzamine on A-receptors

46
Q

Give an example of a Partial agonist and receptor

A

Morphine + Buprenorphine at opioid µ-receptor

Buprenorphine will potentiate withdrawal in an addict

47
Q

Therapeutic Index is measurement of ______ ______.
[steep / flat] slopes that are [near / far apart] are best.

Formula?

Mnemonic

A

Therapeutic index is a measurement of DRUG SAFETY.
STEEP slopes that are FAR APART are best.

LD50 / ED50 —> Median Lethal (or toxic) dose / Median effective dose.

¶ TILE: TI = L / E

48
Q

4 Examples of drugs with LOW therapeutic index!!!

A
  1. Theophylline (p.576)
  2. Digoxin (p.309)
  3. Warfarin (p.395)
  4. Lithium (p.499)

Pharmacology (6 decks)

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