Preliminary Study on the Development of Nanoemulsions for Carbamazepine Intravenous Delivery: An Investigation of Drug Polymorphic Transition

Carbamazepine (CBZ) is available on the pharmaceutical market as tablets, capsules, and oral suspensions, but not as a parenteral formulation for clinical use. Parenteral emulsions are a good alternative to poorly water-soluble drugs such as CBZ. In this way, four different emulsions containing 3 mg/mL of CBZ were developed, but during a period of storage, drug crystal precipitates appeared. To investigate this phenomenon, differential scanning calorimetry, infrared spectroscopy, and light microscopy were employed. The results suggested a polymorphic transition from beta form to dehydrate form, resulting in drug precipitation, although the emulsions themselves remained stable for at least three months.