Drug Kinetics Flashcards
What is the molecularity of reaction
No. Of molecules or atoms that must collide simultaneously to give the products
Unimolecular
Bimolecular
Termolecular
1 type of molecule stoichiometrically involved
2 type
3 or more (less likely to happen because these molecules with sufficient kinetic energy must meet simultaneously in same region of space)
What is order of a reaction
No. of concentration terms on which the rate of reaction depends when determined experimentally
Zero order reaction
The reaction in which the conc of reactant is independent on the rate of reaction
Equation for zero order
Ko = (a - c )
———
t
Examples of zero order
Colour loss reactions
Oxidation of Vit. A
Photochemical degradation of chlorpromazine in aq.sol.
Half life
Time required for a reactant’s concentration to become half of its initial concentration
Shelf life
Time required for the concentration of reactant to reduce to 90% of its initial concentration
Pseudo zero order
A first order reaction which behaves like a zero order reaction
Example of pseudo zero order
Drug degradation in suspension
First order reaction
Rate of reaction depends on concentration of one reactant
Examples of first order reaction
Decomposition of H2O2
Acid hydrolysis
Inversion of sugar
Growth of MO
Equation for first order
K1 = 2.303 log [co/ct]
——–‐—————-
t
Pseudo first order
Originally 2nd order but behaves like 1st order
Examples of pseudo first order
Hydrolysis of sucrose to glucose and fructose
Acid catalyzed hydrolysis of digoxin and erythromycin oxime
