The use of ill selected excipients in drug formulations can have a significant influence on the overall stability. Therefore, evaluation of chemical and physical excipient compatibility with the API has become a major part in the development of new drug products. Moreover, general and individual limits for excipient impurities have also been set by the Ph. Eur. However, batch to batch variability of these excipient impurities, although still Ph. Eur compliant, can cause significant variability in the stability profile of finished drug product.
Recently, large manufacturer and batch to batch variability in hydroperoxide levels was documented in common used pharmaceutical excipients such as povidone, polysorbate 80, PEG 400 and hydroxypropylcellulose [1]. As a result, oxidation sensitive drugs, e.g. raloxifene HCl, can demonstrate inconsistent stability profiles when combined with aforementioned excipients [2]. Another example in which a miconazole-BHT adduct is formed, can be traced back to the petrolatum vehicle, containing BHT, used for topical application [3]. Note that no BHT limits are mentioned in the corresponding Ph. Eur. monograph.
We evaluated the short-term storage stability of three triple intrathecal (Triple IT) solution batches under various conditions [4]. The Triple IT solution, containing cytarabine, methotrexate and methylprednisolone (21)-sodium succinate (MPSS), is used in the treatment of leukemia, lymphoma and brain cancers. Hydrolysis of MPSS to methylprednisolone was found to be the predominant degradation reaction. However, different MPSS degradation kinetics were observed. This observation was linked to the use of different batches of MPSS starting material, i.e. Solu-Medrol®, thus providing an inconsistency in the degradation profile.
References
[1] Wasylaschuk, W.R.; Harmon, P.A.; Wagner, G.; Harman, A.B.; Templeton, A.C.; Xu, H.; Reed, R.A. Evaluation of hydroperoxides in common pharmaceutical excipients (2006). Journal of Pharmaceutical Sciences; 96; 106-116.
[2] Hartauer, K.J; Arbuthnot, G.N.; Baertschi, S.W.; Johnson, R.A.; Luke, W.D; Pearson, N.G.; Rickard, E.C.; Tingle, C.A.; Tsang, P.K.S.; Wiens, R.E. Influence of peroxide impurities in povidone and crospovidone on the stability of raloxifene hydrochloride in tablets: identification and control of an oxidative degradation product (2000). Pharmaceutical Development and Technology; 5; 303-310.
[3] Zhang, F.; Nunes, M. Structure and generation mechanism of a novel degradation product formed by oxidatively induced coupling of miconazole nitrate with butylated hydroxytoluene in a topical ointment studied by HPLC-ESI-MS and organic synthesis.
[4] D’Hondt, M.; Vangheluwe, E.; Van Dorpe, S.; Boonen, J.; Bauters, T.; Pelfrene, B.; Vandenbroucke, J.; Robays, H.; De Spiegeleer, B. Stability of extemporaneously prepared Triple inthrathecal solution of cytarabine, methotrexate and methylprednisolone sodium succinate (in press). American Journal of Health-System Phamacy
