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42 Cards in this Set
- Front
- Back
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what is dc/dt in zero order
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-Ko
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what order is color change/loss of color and why
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zero order b/c it doesn't depend on the concentration
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what is dc/dt infirst order
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-K1C
decomposition depends on concentration of active ingredient |
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what are 90% of decomposition products
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first order
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what is dc/dt in second order
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-K2C1C2
dependent on pH and concentration of active drug |
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how can you get a second order reaction to become 1st order
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buffer the solution therefore making the pH constant or make the concentration constant
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how can you get a second order reaction to be zero order
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make both the concentration and pH constant
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what is the integrated equation for zero order
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C = Co - Kt
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what is the integrated equation for first order
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lnC = lnCo - Kt
or lnCo/C = Kt |
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what is the integrated equation for second order
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1/C = 1/Co + Kt
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what is the half life of zero order
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Co/2K
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what is the half life of first order
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0.693/K
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what is the half life of second order
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1/CoK
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what order half lives are dependent of Co
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zero and second
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what order has these units
conc*time-1 |
zero
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what order has these units
t-1 |
first order
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what order has these units
conc-1 * time-1 |
second order
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in a buffered suspension of ASA what order is it
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zero order because both concentrations are constant
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in a unbuffered suspension of ASA what order is it
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first order because only ASA is constant
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in a unbuffered solution of ASA what order is it
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second order because both concentration are changing
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what is the slope of zero order and y
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slope = -k
y = C \ |
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what is the slope of first order and y
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slope = -k
y = lnC \ |
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what is the slope of second order and y
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slope = k
y = 1/C / |
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in a specific acid-base catalysis what catalyzes the reaction
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acid, base, or both
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if general acid base catalysis what catalysis the reaction
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besides the acid and base the reaction may also be catalyzed by the buffer species (phosphates, citrates, acetate ions)
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in arrhenius equation what is Ea
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minimum energy required to start the decomposition process
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in arrhenius equation what is A
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number of collisions of the reactants per unit time
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what kind of solvents are bad for stability
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polar solvents
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what is done in Accelerated Stability Studies
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if stable for 3 months at 40 degrees (+/-2) and at 75% RH (+-7%) this may be considered as 2 years stability at RT for marketing new dosage form.
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what parameters is long term stability conducted at
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25 degree (+-2) and 60% RH (+-6)
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how would accelerated stability not work
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if Ea is low (below 7kcal/mole) since at low Ea the rxn may not be accelerated at higher temp.
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when do you estimate esp date
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when Ea is not available
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for each 10 degree rise in temp what happens to the rate
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it increases 2-5 times
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when temp increases what is the base
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5
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when temp decreases what is the base
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2
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what happens to exp date when temp increases
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gets shorter
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what happens to exp date when temp decreases
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gets longer
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in complex reactions what is Kf and Kr
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Kf is drug loss
Kr is drug formed |
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what is the effect on ionic strength when both ions have the same charge, diff charge, and one is a molecule
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same charge = K increases
diff chage = K decreases molecule = zero charge |
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what is an example of a complex reaction
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tetracycline decomposing to epitertracycline
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what is an example of drugs that decompose according the parallel rule/side reaction
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corticosteroids, hydrocortisone, prednisone, dexamethasone
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what are the properties of complex reactions
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reversible
slope = kr + kf / |
