Arrange different dosage forms
with deceased bio-availability :
Solution > suspention
>capsule >tablet >coated tablet
* at process of abs. Drug should be in molecular
form
*soln
:drug in molecular form :abs immediately.
*in susp:
very small fraction in molecular ,the rest is suspended.
*in capsule (solid drug + inert diluent ) enclosed in a shell made of gelatin-sucrose mix.
#the more steps added to dosage form u
expect more difficulty.
*in tablet :should disintegrate
first into granules then to drug / soln (add
more obstacle ,takes time for drug to be dissolved and be in molecular form.
# there is equilibrium , when
drug in soln abs. , shift the drug in solid
form to compensate another fraction.
#tablet is the most commom
(stable solid ,covered by coat ,transported easily ,easy handle ,economic )
#adjust wt of tablet >const supply of punsh determined by tablet machine >const dose
#u should add disintegrant
with granules to abs water from GIT eg starch.
#moistening of pw
to make daw > sieve >granules by (starch mu ,gum mu ,sucrose serum which
are viscous)
#drying at RT or in vacuum oven
so
tablets contain many additives & many steps
#compression force should be calc
otherwise tablet will become as a piece of cement and will overcome the propertue of disint. And pass
through GIT without abs.
Due to
1-to much binder
2-high compression
3-poor quality disint.
4-insufficient disint
#some times add colouer
sub. For attracrion (certified dye by pharmacopeai)
*coated tablet ,coat could be sugar
(sucrose serum ) or polymer >thin film around tablet
#film should be proper >as it may
abs water and deteriorate the drug.
THE RELATIONSHIP
BETWEEN BLOOD CONC& PHARMACOLOGICAL EFFCT :
*AT ZERO TIME OF TAKEN DRUG ORALLY (BY ANY ROUTE EXCEPT IV) durg in blood = zero till mini,um effective conc
increase time increase drug conc
in blood then decrease drug conc as dose is consumed (completely abs)
*once the dru
enter the bl. (dynamic mov)
>excreation & metab.
Process of metabolism starts as soom as drug in
blood
*any stepat which
drug is subjected is kinetic (1st order)
bell shaped curves