Inclusion Compound of Efavirenz and gamma-Cyclodextrin: Solid State Studies and Effect on Solubility


Efavirenz is an antiretroviral drug of widespread use in the management of infections with human immunodeficiency virus type 1 (HIV-1). Efavirenz is also used in paediatrics, but due to its very poor aqueous solubility the liquid formulations available resort to oil-based excipients. In this report we describe the interaction of gamma-cyclodextrin with efavirenz in solution and in the solid state. In aqueous solution, the preferential host-guest stoichiometry was determined by the continuous variation method using H-1 NMR, which indicated a 3:2 host-to-guest proportion. Following, the solid inclusion compound was prepared at different stoichiometries by co-dissolution and freeze-drying. Solid-state characterisation of the products using FT-IR, C-13{H-1} CP-MAS NMR, thermogravimetry, and X-ray powder diffraction has confirmed that the 3:2 stoichiometry is the adequate starting condition to isolate a solid inclusion compound in the pure form. The effect of gamma-cyclodextrin on the solubility of efavirenz is studied by the isotherm method.

subject category

Biochemistry & Molecular Biology; Chemistry, Multidisciplinary


Braga, SS; El-Saleh, F; Lysenko, K; Paz, FAA

our authors


We acknowledge University of Aveiro and FCT/MCTES (Fundacao para a Ciencia e a Tecnologia, Ministerio da Ciencia, da Tecnologia e do Ensino Superior) for financial support for the QOPNA research Unit (FCT UID/QUI/00062/2019), LAQV-REQUIMTE (Ref. UIDB/50006/2020) and CICECO-Aveiro Institute of Materials (UIDB/50011/2020 and UIDP/50011/2020), through national founds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement. The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through the operational programme COMPETE 2020, POCI and PORL and FCT through PIDDAC).

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