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To the Pharm Group
A survey of sorts...
What would be the top five -six bio/physiological parameters ( other than
weight, age ) you would want to ascertain and which you ( or the attending )
could reasonably obtain for the appropriate dispensation of a single 20-30 min
, 14 mg/kg infusion of procainamide ( class 1a ) to relatively healthy hearts
in an effort to terminate a paroxysmal bout of atrial fibrillation -
infrequent prior episodes eg monthly, no PVDs.
If a single dose did not terminate the AF, would you administer a second
dose, if so how long would you wait ?
If the first episode was terminated by the first dose, and AF reappeared one
or two hours later, would you administer a second dose ( accomodating the
elimination factor ) or move on to a second therapy ?
Thanks in advance
PBuscemi
PharmaTar.at.aol.com
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Dear Dr. Buscemi:
I would like to know age, gender, height, weight, serum creatinine
(so I
could estimate CCr), and I would like to use a population pk model of
procainamide to guide me in developing the initial regimen.
I would want to titrate the patient up through the range of serum
levels
until he either converts or the levels become high enough for concern,
perhaps about 12-14 ug/ml. I would do this by starting with a target goal
of about 5 ug/ml, for example. Using the population model in our USC*PACK
programs, and considering a 50 year old male, 70 in tall, weighing 70 kg,
with a serum creatinine of 1.0 mg/dL, this could be achieved by giving
about 600 mg IV over one hour, watching the patient's response throughout.
If he converts, then fine. One can either do nothing, or can put him on an
oral regimen to achieve an average of about 5 ug/ml, again using the
software to compute the appropriate maintenance dose.
If he did not respond, then I would gently titrate him upward
toward goals
of 8, 10, or 12 ug/ml, again using the same format of a 1 hour infusion
plus the appropriate maintenance infusion, appropriately adjusted to follow
his prior therapy, to hit the desired target goal.
Bear in mind that similar titration with digitalis also converts people
with AF, (and I prefer digitoxin over digoxin, because of its better
absorption, fewer arrhythmias as a first manifestation of toxicity, LONGER
half-time, and lesser sensitivity to renal function. We can talk about this
more if you want.
Best regards,
Roger Jelliffe
************************************************
Roger W. Jelliffe, M.D.
USC Lab of Applied Pharmacokinetics
CSC 134-B, 2250 Alcazar St, Los Angeles CA 90033
Phone (213)342-1300, Fax (213)342-1302
email=jelliffe.aaa.hsc.usc.edu
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