Lipids are increasingly used in development of new dosage forms as matrix carriers to prepare lipophilic solid dispersion for sustained release solid dosage forms. Therefore solid lipids, that are made by physiological materials, are advantageous pharmaceutical excipients, being low cost natural products with harmless and well-tolerated physiological properties; additionally it must be outlined the fact that glycerides are subject to lipase action and this makes their use of biological importance. Compared to systems formed by the association between a drug and a polymer, lipids have the advantage of a better bio-compatibility which minimizes the hazards of acute and chronic toxicity. In particular solid lipid particles, at micro- and/or nano-scale, possessing matrix made from fatty acids, glycerides, fatty alcohols and solid waxes with high melting point, behave as drug carriers for a controlled as well as sustained drug release, being the lipid coating impermeable to aqueous media and not immediately permeable to the dispersed drug or ready to be dissolved or solubilised, as a consequence they can be used for protection of drug active and/or taste masking. Recently pharmaceutical industry made available new lipid materials by suitable processing of natural substrates or with balanced mixture of natural, semi-synthetic or fully synthetic compounds of lipid nature: polyglycolized glycerides are available with a range of properties depending on their hydrophilic lipophilic balance (HLB) over the range of 1 to 18 and melting point between 33 and 70°C with the trade name of Gelucires; or Precirol and Compritol. Most of these materials are complex mixtures in order to balance the physical and chemical properties and also crystallinity is reduced since many imperfections are present in the solid state suitable to accommodate the drug, preventing re-crystallization phenomena typical of the aging of lipid solid dispersions. Other lipid associations can be designed in order to govern the release of the embedded drug in the lipid matrix, such the addition of a fatty (such as stearic) acid to a wax or triglyceride to introduce a control by pH. Thermal analysis evidenced that often these systems do not form homogeneous phases in the solid state, as shown by the presence of two separated melting endotherms, having peak temperature shifted for the formation of two mutually saturated systems. In these cases the active agent can be partitioned between the two phases, making the system less suitable to saturation: the drug could reach saturation with difficulty even at high loading. The control of the release can result even more efficient, since the drug is inserted into different carriers and experiments the different behaviour of each phase.
Lipid association in controlling the release of drugs / A. Fini; C. Cavallari. - STAMPA. - (2009), pp. J026-J026. (Intervento presentato al convegno I Congreso Iberoamericano de Química, Bioquímica e Ingenieria Química. VII Congreso Internacional de Química e Ingeniería Química tenutosi a La Habana (CUBA) nel Oct 12 -16, 2009).
Lipid association in controlling the release of drugs
FINI, ADAMO;CAVALLARI, CRISTINA
2009
Abstract
Lipids are increasingly used in development of new dosage forms as matrix carriers to prepare lipophilic solid dispersion for sustained release solid dosage forms. Therefore solid lipids, that are made by physiological materials, are advantageous pharmaceutical excipients, being low cost natural products with harmless and well-tolerated physiological properties; additionally it must be outlined the fact that glycerides are subject to lipase action and this makes their use of biological importance. Compared to systems formed by the association between a drug and a polymer, lipids have the advantage of a better bio-compatibility which minimizes the hazards of acute and chronic toxicity. In particular solid lipid particles, at micro- and/or nano-scale, possessing matrix made from fatty acids, glycerides, fatty alcohols and solid waxes with high melting point, behave as drug carriers for a controlled as well as sustained drug release, being the lipid coating impermeable to aqueous media and not immediately permeable to the dispersed drug or ready to be dissolved or solubilised, as a consequence they can be used for protection of drug active and/or taste masking. Recently pharmaceutical industry made available new lipid materials by suitable processing of natural substrates or with balanced mixture of natural, semi-synthetic or fully synthetic compounds of lipid nature: polyglycolized glycerides are available with a range of properties depending on their hydrophilic lipophilic balance (HLB) over the range of 1 to 18 and melting point between 33 and 70°C with the trade name of Gelucires; or Precirol and Compritol. Most of these materials are complex mixtures in order to balance the physical and chemical properties and also crystallinity is reduced since many imperfections are present in the solid state suitable to accommodate the drug, preventing re-crystallization phenomena typical of the aging of lipid solid dispersions. Other lipid associations can be designed in order to govern the release of the embedded drug in the lipid matrix, such the addition of a fatty (such as stearic) acid to a wax or triglyceride to introduce a control by pH. Thermal analysis evidenced that often these systems do not form homogeneous phases in the solid state, as shown by the presence of two separated melting endotherms, having peak temperature shifted for the formation of two mutually saturated systems. In these cases the active agent can be partitioned between the two phases, making the system less suitable to saturation: the drug could reach saturation with difficulty even at high loading. The control of the release can result even more efficient, since the drug is inserted into different carriers and experiments the different behaviour of each phase.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
