pharmactherapeutics Flashcards
(47 cards)
explain repeat administration
is a drug that is eliminated by first order kinetics is administered repeatedly, the average plasma conc of the drug will increase to a steady state level
will drugs that show zero order elimination be able to reach steady state level
no
what is the time required to reach steady state level
5 half lives
how do we control the magnitude of fluctuations in steady state level
by using a dosing interval
what will a shorter dosing interval do to the fluctuations
decrease them
what will a longer dosing interval do to the fluctuations
increase them
on cessation of multidose administration what will happen to the drugs elimination
94-97% of the drug will be eliminated in a time interval equal to five half lives
how high is the mean of the plasma conc during steady state in relatio to the Cmax after first application
its 1.44 time higher
when should we use a loading dose
when the therapeutic conc of a drug in the plasma must be achieved rapidly
how do we calculate the loading dose
select the desired plasma conc of drug and multiply that by the Vd
after giving the loading dose how do we continue to administer the drug
at the maintenance dose rate to maintian the drug conc at the steady state
equation to calculate dose rate,
dose rate = Cl x desired drug plasma
whats the maintenance dose rate
the dose of a drug required per unti time ot maintain a steady state level in the plasma to sustain a therapeutic effect
how is dose rate expressed
mg/hour
what can ampicillin cause in horses
colitits
atorpine can cause what in horses
systemic side effects with local application
ivermectin effect in dogs
MDR1 gene, in 1/3 of collies and australian shepherds - ivermectin can lead to paralysis in sensitive animals
what can sulphonamides cause in dogs
idiosyncratic reactions
how can a fever affect drug action
reduced emptying of stomach, negative effect on absorption
how can diarrhoea affect drug action
increased gut motility, decr bioavaliability, exsiccation
how can gender affect drug action
in males metabolism could be faster, testosterone is a CYP3A inducer
altered physiology to do with absorption that can be seen in older animals
decr gastric acid secretion, incr gastric pH, decr GI blood flow, decr pancreatic trypsin, decr GI motility
clinical considerations of the altered physiology that can be seen in older animals
altered dissolution rate, possible decr absorption, time of onset delayed
altered physiology of body composition in older animals
decr in total body water, decr lean body wight and inc in body fat
