| Prednisone is practically insoluble
in water and soluble 1 in 150 parts of ethanol. Prednisolone
is very slightly soluble in water
and soluble 1 in 30 parts of ethanol.
Oral liquids of prednisolone, prednisolone sodium phosphate and prednisone are commercially available in many countries. Prednisone suspensions usually have a pH of 3 - 4.5 and contain 2 - 5% ethanol; solutions have a pH 2.6 - 3.6 and contain 4-6% ethanol.
A number of extemporaneously prepared formulations have been described1-5 and pharmacists often develop their own variations. The basic principles are:
- Inclusion of a co-solvent (usually ethanol) to increase solubility.
- Avoidance of alkaline pH as chemical degradation occurs more rapidly under these conditions.
- If sodium benzoate is used as a preservative the final pH must be less than 5, preferably about 4.
- Flavoured suspending bases are often used to disguise the bitter taste.
- Preparations should be protected from light.
- Some of the formulations studied have used prednisolone or prednisone powder and the conclusions cannot be applied to formulations prepared from tablets due to possible effects of tablet excipients.
- Expiry dates should not exceed one month unless the formulation has been fully validated.
- Gupta VD, Gibbs CW, Ghanekar AG. Stability of pediatric liquid dosage forms of ethacrynic acid, indomethacin, methyldopate hydrochloride, prednisone and spironolactone. Am J Hosp Pharm 1978; 35 (Nov): 1382-1385.
- Sullivan JA, Hobson LT. Prednisolone disodium phosphate stability in a prednisolone oral solution. Aust J Hosp Pharm 1994; 24 (5): 397-398.
- Sullivan JA. Prednisolone stability in a hydroalcoholic prednisolone mixture. Aust J Hosp Pharm 1991; 21 (Aug): 239-241.
- Stafford L, Hope ME, Janney EP, Ailakis JG. Comparison of paediatric steroid mixtures. Aust J Hosp Pharm 1998 28 (4): 246-249.
- Gupta VD. High pressure liquid chromatographic evaluation of aqueous vehicles for preparation of prednisolone and prednisone liquid dosage forms. J Pharm Sci 1979; 68 (Jul): 908-910.