|Formulation in Pharmacy Practice 2nd Edition|
Diazepam has a solubility in water of 0.05mg per mL;
Newton et al3 reported that a diazepam oral liquid prepared from tablets in a syrup base with 30% propylene glycol and 5% ethanol was stable for at least 14 days at room temperature in amber glass bottles. The amount of propylene glycol in this formulation may be unacceptable. In the same study, a 1mg per mL suspension compounded from tablets and unpreserved Syrup USP, was reported to be chemically stable, but dose uniformity may be erratic as the preparation is a solution/suspension of diazepam.
Strom4 studied the stability of a diazepam oral liquid prepared from tablets containing 3.6% v/v of ethanol 95% and 5% v/v of propylene glycol in a syrup base with 1% sodium carboxymethylcellulose and 2% magnesium aluminium silicate. The pH was adjusted to 4.2 with hydrochloric acid. The preparation was stable for 60 days at room temperature or under refrigeration.
Most tablet brands disperse rapidly and this option should be considered before making an oral liquid.
The following formulation is based on published studies and stability data.
Formulation in Pharmacy Practice
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