The volume of suppository for particular mould in uniform but its weight will vary because of difference of density of base & medicament used. For this displacement valve of medicament is taken in consideration.
Displacement value is defined as : The quantity of drug which displace one part of the base.
The Displacement value of a given medicament can be determined as

B= Indicate Base; M indicate= Medicament/Drug;
a= amount of pure base suppository (without medicament/drug);
d= amount of medicament/drug;
c=amount of base after medicament is incorporated
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The volume of suppository for particular mould in uniform but its weight will vary because of difference of density of base & medicament used. For this displacement valve of medicament is taken in consideration.
Displacement value is defined as : The quantity of drug which displace one part of the base.
The Displacement value of a given medicament can be determined as

B= Indicate Base; M indicate= Medicament/Drug;
a= amount of pure base suppository (without medicament/drug);
d= amount of medicament/drug;
c=amount of base after medicament is incorporated
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Example”-
Q. Calculate the displacement of medicament in cocoa butter suppositories containing 40 % medicament, prepared in 1 gm suppository Mould. The wt of 10 medicated suppositories is 15 gm.
A) 6
B) 10
C) 15
D) 4
View Answer
A
Solution:-

Wt. of 10 Pure base suppositories/’a’ = No. of suppositories x Mould size
a= 10 x 1 gm= 10 gm
Wt. of 10 Medicated suppositories(base+ medicament) ”= 15 gm;
Since suppositories contain 40 % Medicament so amount of amount= 40 % of 15 gm= (40/100) x 15 gm= 6 gm medicament/drug
So there is 6 gm is medicament than amount of base is= total wt of suppositories– wt of medicament=15-6= 9 gm base
so Displacement value= d/ (a-c)=6/(10-9)=6/1=6
Q. Each Theobroma oil suppository contains 500 mg of Zno , when prepared in 1gm suppository mould . What will be the quantity of base in 10 medicated suppositories? (D.V. of Zno is 5)
- A) 9 ml
- B) 9 gm
- C) 5 ml
- D) 5 gm
View Ans
B
SOLUTION:
Displacement value of ZnO=5 is given
One Medicated Suppository containing 500 mg of Zno, So total 10 medicates suppositories containe ZnO=500 mg x 10=5000 mg or 5 g ZnO so value of ‘d‘=5g
Wt of an one pure base Suppositories 1 g so Weight of 10 Pure base suppositories = 1×10= 10 gm or 10000 mg= so value of ‘a’=10 gm
Now we have to find out the value of ‘c’
Displacement value = d/(a-c)=
5= 5 g/(10-c)={ 5/5=10-c}={1=10-c}
1+c= 10
c=10-1=9 gm
Displacement value of Drug= d/(a-c)
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