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An advantage of a high hydroxyl number is the larger melting and solidifying range which permits
easier manufacturing. In some cases, the water number can be increased by the addition of surface
active agents.
6- Acid value

❖ The number of milligrams of potassium hydroxide required to neutralize the free acid in 1
gm of substance is expressed by this value.

❖ Low acid values or complete absence of acid are important for good suppository bases.
❖ Free acids complicate formulation work because they react with other ingredients and can

also cause irritation when in contact with mucous membranes.
a) Theobroma oil (cocoa butter)

❖ It is of natural source composed of glyceryl ester of fatty acid e.g. stearic, palmitic
(saturated), and oleic acid (monounsaturated).

❖ Melted at 30-36C (melt just below the body temperature).
❖ It is yellowish color solid at room temperature with a chocolate odour.
❖ Not suitable for tropical countries.

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