Pharm Basics Flashcards

1
Q

Km

A

The concentration at which the reaction is half of maximum. Lower the Km, the higher the affinity.

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2
Q

Michaelis-Menten Equation

A

Vmax*S/Km+S

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3
Q

Michaelis-Menten Equation

A

Vmax*S/Km+S

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4
Q

Lineweaver Burk Plot

A

Plots against 1/V and 1/s

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5
Q

X intercept on lineweaver burk?

A

-1/Km. The further to the right (closer to zero), the lower the affinity

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6
Q

Y intercept on lineweaver burk

A

1/Vmax.

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7
Q

Slope on lineweaver burk

A

Km/Vmax

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8
Q

Slope on lineweaver burk

A

Km/Vmax

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9
Q

Characteristics of a reversible competitive inhibitor

A

Resemble substate, overcome by increasing S, bind active site, DO NOT CHANGE VMAX, increase Km.

Decrease potency of an enzyme

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10
Q

Characteristics of an irreversible competitive inhibitor

A

Resemble substate, not overcome by increasing S, bind active site, decrease Vmax, don’t change Km.

Decrease efficacy of an enzyme

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11
Q

Characteristics of an irreversible competitive inhibitor

A

Resemble substate, not overcome by increasing S, bind active site, decrease Vmax, don’t change Km.

Decrease efficacy of an enzyme

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12
Q

Noncompetitive inhibitor characteristics

A

Don’t resemble substrate, not overcome by increasing S, don’t bind active site,

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13
Q

Bioavailability

A

Fraction of administered drug that reaches systemic circulation unchanged. IV dose, F=100. For oral dose, F

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14
Q

Volume of distribution equation

A

Amount of drug in the body/plasma drug concentration

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15
Q

Drugs with low Vd

A

Remain mostly in blood, these include large/charged molecules

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16
Q

Drugs with medium Vd

A

Mostly in EFC. Include small hydrophilic molecules

17
Q

Drugs with large Vd

A

Mostly in tissues including fat. Small lipophilic molecules especially if bound to tissue protein

18
Q

Half-life equation

A

(0.693 x Vd)/CL

19
Q

How many half-lives does it take to reach steady state?

A

3.3 to reach 90%. 4 or 5 to reach full steady state.

20
Q

Clearance equation

A

Rate of elimination of the drug/plasma drug concentration.

VdXke (elimination constant)

21
Q

Loading dose

A

(Cp X Vd)/ F

Cp is target plasma concentration

22
Q

Maintenance dose

A

(CpXCLxt)/F

23
Q

Zero order elimination

A

Rate of elimination is constant and not based on the amount of drug in the body. Includes Phenytoin, ethanol, aspirin (at high doses)

24
Q

First order elimination

A

Rate of elimination is directly proportional to the drug concentration. There is a constant fraction of drug eliminated per unit time.

This is flow-dependent elimination

25
Weak acids
Treat overdose with bicarbonate, because are ionized in basic environment. Phenobarbital, methotrexate, aspirin
26
Weak bases
Trapped in acidic environments, treat overdose with ammonium chloride.
27
Weak bases
Trapped in acidic environments, treat overdose with ammonium chloride.
28
Phase 1 metabolism
Oxidation/reduction/hydrolysis (usually cyp450)
29
Phase 2 metabolism
Glucuronidation, acetylation, sulftation. Yields very polar, inactive metabolites that are renally excreted.
30
Phase 2 metabolism
Glucuronidation, acetylation, sulftation. Yields very polar, inactive metabolites that are renally excreted.
31
Efficacy of a drug
The maximal effect a drug can produce. High efficacy drugs include analgesics, antibiotics, antihistamines, and decongestants.
32
Potency of a drug
The amount of drug needed for a given effect. Increased affinity for receptors. Include chemotherapeutics, antihypertensives, and cholesterol drugs
33
Competitive antagonist effect on curve
Shifts to the right, decreases the potency. Flumazenil (on gaba)
34
Noncompetitive antagonist/irreversible competitive antagonist effect on curve
Shifts it down. Prevents maximal effect. (ketamine is noncompetitive, phenoxybenzamine is irreversible competitive on alpha receptors
35
Therapeutic index
A measurement of drug safety. TD50/ED50 = median toxic dose/ median effective dose. Safe drugs have high TIs. Low TI drugs include theophylline, digoxin, lithium
36
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