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I am working on preparation of extended release formulation of
promethazine HCl using solid dispersion approach. I have some doubts
The maintenance dose of promethazine HCl for sustaining the release
for 12 h comes to 75 mg by taking f = 0.88. Is it correct? As this is
a salt, should we take the amount equivalent to promethazine in the
Sir, is it always necessary to separately add the loading dose in
such a formulation?
Also, I want to know that is it feasible to formulate any oral
controlled release formulation which can release the drug for 24 h,
as any system hardly resides in g.i.t. for 24 h. In such a case, how
can we justify once a day formulation for oral route?
How can we predict/know the gastrointestinal transit time of any
drug? In equation LD = Io/ke, where LD is the loading dose (mg),Io =
the dosage form zero order release rate (mg/hr). How I0 can be
calculated for any drug?
Department of Pharmaceutics
Rajiv Academy for Pharmacy,
NH#2, Delhi-Mathura Bypass Road,
PO Chattikara, Mathura - 281 001,
Uttar Pradesh, INDIA.
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