Pharm p. 242-244 Flashcards
What variable represents Michaelis-Menten constant?
Km
enzymatic reactions that exhibit a sigmoid curve usually —– kinetics.
indicate cooperative
Km is —- related to the affinity of the enzyme for its substrate.
inversely
Most enzymatic reactions follow hyperbolic
curves like:
Michaelis-Menten kinetics
Vmax is directly proportional to the enzyme —-.
.
concentration
Formula for Km? Km =
Km = [S] at 1/2 Vmax
According to Michaelis-Menten kinetics, Vmax is the point at which the enzymes are —-.
saturated
In Lineweaver-Burk plot, the higher the y-intercept, the — Vmax.
lower
In Lineweaver-Burk plot, on the x-axis, the closer to zero, the —- the Km and the —- the affinity.
greater
lower
How can one distinguish btw reversible and non-reversible inhibitors on the Lineweaver-Burk plot?
Reversible competitive inhibitors cross each
other competitively, whereas noncompetitive
inhibitors do not.
Do irreversible Competitive inhibitors bind to the active site?
Yes, only Non-comp. don’t.
T or F? Irreversible Competitive inhibitors incr Vmax.
F. decr
T or F? reversible Competitive inhibitors dcr Km.
F. incr
T or F? Irreversible Competitive inhibitors incr efficacy.
F. decr
T or F? reversible Competitive inhibitors decr efficacy.
F. Unchanged
Which kind of inhibitors can be overcome by incr [S]?
reversible Competitive inhibitors
Formula for Vd?
Vd = (amount of drug in the body) /
(plasma drug concentration)
Liver and kidney disease decr protein binding to drugs causing — Vd.
incr
Drugs that are large/charged molecules and plasma protein bound have a —- Vd.
Low
Drugs that are small lipophilic molecules and bound
to tissue protein are found in which tissues?
All tissues, specially fat tissue
Formula for Cl?
CL= (rate of elimination of drug) /
(plasma drug concentration)
Formula for Cl in terms of Vd?
Cl = Vd × Ke (elimination constant)
If a drug is mostly found in the blood, what is its Vd?
low
Time to steady state depends primarily on — and is independent of —- —-.
t1/2
dose and dosing frequency
Loading dose =
Loading dose = (Cp × Vd) / F
A drug infused at a constant rate takes — half-lives
to reach steady state.
4–5
Maintenance dose =
MD = (Cp × CL × τ) / F
t1/2 =
t1/2 = (0.693 × Vd) / CL
It takes — half-lives to reach 90% of the steady-state level.
3.3
In renal or liver disease, maintenance dose — and
loading dose is usually —–.
decr
unchanged
If a drug is mostly found in the ECF, what are the properties of the drug?
Made out of small hydrophilic molecules
after 4 half-lives, what % of the drug is remaining in body?
6.25%
A constant amount of drug eliminated per unit time is called?
Zero-order elimination
To treat overdose of a weak acidic drug one must administer what kind of drug?
basic drug
To treat overdose amphetamines, give which drug?
ammonium chloride
Examples of 3 drugs with Zero-order elimination at
high or toxic concentrations?
Phenytoin, Ethanol, and Aspirin “PEA”
A constant fraction of drug eliminated per unit time is called?
First-order elimination
Another name for Zero-order elimination?
Capacity-limited elimination.
Give 4 examples of acidic drug OD that Bicarbonate can treat?
phenobarbital
methotrexate
aspirin
TCAs
Another name for First-order elimination?
Flow-dependent elimination
In Phase II of metabolism, what is Conjugation referred to? “GAS”
Glucuronidation,
Acetylation,
Sulfation
Which of the met. phases yields metabolites that are renally excreted? and why?
Phase II
Because the metabolites are very polar and inactive
