Chimeral Agglomerates of Microparticles for Nasal Administration of Analgesic Drug Powders

Recently, nasal route has received a great deal of attention as a method for systemic administration of drugs, especially those that have to be administered by injection. The nasal route is advantageous because of the rapid absorption of drug molecules across the nasal mucosa and the relative ease of administration (1). Nasal powder formulations may improve chemical and microbiologic stability of the drug over liquid formulation, allowing larger amounts of drug to be administered. In any case, the effectiveness of nasal preparations depends on their appropriate deposition inside the nasal cavity. Nasal powders face similar technological paradox as inhalation powders: the particles must be small for aerosol delivery and drug dissolution, but large enough for handling during manufacturing of dosage form. This technological drawback could be solved by particle agglomeration, which is a process used to increase the powder particle size giving rise to microparticle clusters (2). These agglomerates are defined “chimeral” since their size is reversed by insufflation. Agglomerates have big size for easier dosage form manufacturing; the “chimeral” definition means that their size is temporary, since insufflation produces small fragments suitable for deposition and drug release. This concept of chimeral nasal powder was applied to an analgesic drug in view of its nasal administration for the management of postoperative pain and for moderate-to-severe pain in cancer patients. Hence, this paper describes the pharmaceutical development of a nasal powder of morphine.