Maurizio Cini

Description and preliminary evaluation of a new ultrasonic atomizer for spray-congealing processes

A new atomizer that operates with ultrasonic energy is described. This apparatus is intended to obtain microparticulate drug delivery systems through spray-congealing or spray-drying technologies. In this work, some experimental results are reported on model systems submitted to spray-congealing. The formulations under examination contained theophylline and fenbufen as model drugs and stearic acid, carnauba wax, Cutina HR(R) and Compritol 888 ATO(R) as low melting excipients. Non-aggregate and spherical-shaped microparticles were obtained with all the materials tested; moreover, they had smooth surface and good flowability. The particle sizes depend on the amount of drug present and in each case the maximum size value of the distribution frequency was found to be 375 mu. In vitro release of the drug depends on its solubility and on the excipient lipophilicity. The results suggest that the ultrasound-assisted atomizer could be proposed as a possible alternative to traditional atomizers used for spray-congealing in the pharmaceutical field.

Effect of different polymer-plasticizer combinations on ‘in vitro' release of theophylline from coated pellets

Abstract Plasticizers are added to the polymer coating of sustained-release granules to improve the mechanical properties of the coating shell. The present investigation evaluated the influence of different plasticizer/polymer combinations on theophylline (TH) release from pellets coated with latex aqueous dispersions of ethylcellulose (EC) or acrylic polymers (ACR). The plasticizers, present in the coating films in amounts ranging from 8 to 30%, were acetylated monoglycerides (AMG), diethyl phthalate (DEP), dibutyl phthalate (DBP) and dibutyl sebacate (DBS). The release profiles of TH from the coated pellets were influenced by the type and amount of plasticizer and of coating material, and by the ratio polymer-plasticizer. For both types of coating, the drug release rate decreased with increasing plasticizer content. A correlation was found between the permeability coefficients (Pwv) to water vapour of free films, having the same composition as those used for coating, and drug release.

Effects of ultrasound-assisted compaction on Ketoprofen/Eudragit® S100 Mixtures

Ketoprofen alone and in binary mixtures with Eudragit S100 was compacted by an ultrasound-assisted (US) tableting machine at an energy ranging from 50 to 400 J. The final material was analysed by TLC and HPLC: no decomposition product of the active agent was found. IR spectra and HSM revealed the absence of any interaction between the two components. Thermal analysis (DSC) evidenced that ketoprofen inside the mixtures was transformed into an amorphous state, documented by the decreasing of the DeltaHfus as the Eudragit/ketoprofen ratio increases and as US energy increases. While pure ketoprofen recovers its crystalline state quickly after the US treatment, the presence of Eudragit was found to slow down or possibly to prevent the regeneration of the crystallinity.

Evaluation of theophylline tablets compacted by means of a novel ultrasound-assisted apparatus

Abstract A model formulation containing theophylline and Eudragit® RL was compacted, at energies ranging between 15 and 150 J, by means of a laboratory-scale, novel tabletting machine in which compaction was effected by ultrasound, rather than by mechanical energy. Comparison of the technological and physico-chemical characteristics of the resulting tablets with those of tablets obtained with a conventional tabletting machine evidenced significant differences, suggesting sintering as the main mechanism operating in ultrasound-assisted compaction. The ultrasound-compacted tablets released the drug at lower rates with respect to conventional tablets. The novel technique migh prove useful for the development of sustained-release oral dosage forms containing theophylline or other suitable drugs.

Determination of retinoids in galenicals by column liquid chromatography with fluorescence and diode-array detection

Simple and rapid reversed-phase gradient column liquid chromatography (LC) with fluorescence detection at different wavelengths was developed for the simultaneous analysis of all-trans, 13-cis, 9-cis retinoic acids, vitamin A palmitate and beta-carotene in galenicals. The assay results agreed with those obtained by an LC method with diode-array UV detection. A post-column on-line photochemical reactor (irradiation at 254 and 366 nm) was inserted between the LC column and the fluorescence detector to enhance the performance of the method. Two fluorescence spectra (photoreactor on and off) were obtained for each analyte which proved useful for the unambiguous identification of the various analytes.