Dear forum members,
I have a problem that is causing me a lot of trouble for a while!
I am a head of a team working on a project for
formulating topical powder aerosol preparation of
Neomycin and Bacitracin packed in the pressurized
container (which is not meter dosed).
The formulation is going to be something like this:
Neomycin 87,5 mg (in the form of the sulphate)
Bacitracin 12 500 ij
Colloidal SiO2 ad 25 g of powder mass
Isobuthan 75 g
The propellant we are going to use is Isobuthan
(2-Methylpropan). Total weight of preparation is
going to be 100 g (approximately 186 ml).
USP and FDA describes formulation of this kind,
and declares that there should not be more than
500 units of bacitracin and 3.5 milligrams of
neomycin in each gram
(PART 333--TOPICAL ANTI-MICROBIAL DRUG PRODUCTS
FOR OVER-THE-COUNTER HUMAN USE - Subpart B--First
Aid Antibiotic Drug Products)
http://www.fda.gov/cder/otcmonographs/First_Aid_Antibiotic/first_aid_antibiotic(333B).htm.
So, it is stated that it should be 0.35% of
Neomycin (approximately 0.50% of Neomycin
sulphate).
My question is:
When it is stated ģin each gramī do they mean
each gram of powder that is filed in the can (25
g) or total mass of preparation, including
liquefied gas (100 g)?
Isobuthan is evaporating very quickly after
application, and residual powder that is left on
the skin should be considered for calculation,
but I can not find any document which supports
this presumption.
If I am wrong, and total weight of formulation is
considered for calculation, then my formulation
is sub dosed, but one could prepare formulation
consisting of 350 mg of Neomycin, than add 99.65
g of liquefied gas as propellant (with no inert
powder excipiens), and to declare that it is
formulation that consists of 3.50 milligrams of
neomycin in each gram. But when a patient applies
this aerosol on a skin, he would get 100 % pure
Neomycin sulphate.
Is this permitted? Toxic effect of Neomycin are well described.
Thanks in advance,
Yours truly,
Bojan
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Bojan
pavlovicboyan@gmail.com
GAL
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