Page 11 - Pharmaceutics-II (02-06-01 203)

Classification of suppository base:
The bases of suppository can be classified as follows:
I. Fatty bases.
II. Water soluble bases.
III. Water miscible bases.
IV. Miscellaneous bases.

I. Fatty or oleaginous base:
Fatty bases have some important specifications which are:
1- Melting range

❖ Since fats do not have sharp melting points, their melting characteristics are expressed as a
range indicating the temperature at which the fat starts to melt and the temperature at which
it is completely melted.

2- Solidification point
❖ This value indicates the time required for base solidification when it is chilled in the mold.
❖ If the interval between the melting range and solidification point is 10ºC or more, the time
required for solidification may have to be shortened for a more efficient manufacturing
procedure by augmenting refrigeration.

3- Saponification value
❖ The number of milligrams of potassium hydroxide required to neutralize the free acids and
to saponify the esters contained in 1 gm of fat. It is an indication of the type of glyceride
(mono- or tri-) as well as the amount of glyceride present.

4- Iodine value
❖ This value expresses the number of grams of iodine that react with 100 gm of fat or other
unsaturated material.
❖ The possibility of decomposition by moisture, acids, and oxygen (leads to rancidity in fats)
increases with high iodine values.

5- Hydroxyl number
❖ It refers to the amount of mono and diglycerides present in the fatty base. The high number
means that the amount of water in grams, which can be incorporated in 100 gm of fat, is
high.

This may lead to an increased rate of decomposition for drugs that are easily hydrolyzed such as
acetylsalicylic acid.
High value could lead to the formation of w/o emulsion in the rectum which is generally to be
avoided because of its very low drug release rate.

10