In situ gelling drug delivery systems for periodontal anaesthesia.
In this thesis local anaesthetic formulations based on PEO-PPO-PEO block copolymers (PEO and PPO being poly(ethylene oxide) and poly(propylene oxide), respectively) or nonionic cellulose ethers undergoing temperature- or dilution-induced thickening were investigated. The aim of the work was to develop formulations which can be easily administered to the periodontal pocket, stay at the application site, give a fast onset of anaesthesia and have a duration sufficient to perform periodontal scaling procedures. Emulsions, (mixed) micellar solutions and microemulsions fulfilling the requirements stated above were achieved by combining the active ingredients lidocaine and prilocaine with the nonionic block copolymers Lutrol® F127 and Lutrol® F68. The critical micellisation and gelation temperatures of the systems were found to be interconnected and influenced by the total polymer concentration and the polymer mixture composition, as well as the presence of cosolutes and pH. A low-viscous isotropic phase that turns into a high-viscous hexagonal phase as the water content increases was found by combining Lutrol® F68, water, a eutectic mixture of lidocaine and prilocaine and Akoline MCM. The system has a slower release rate compared to the microemulsion formulation which might make it suitable for indications where a longer duration is needed. Finally, a temperature-induced gelling system was achieved by adding lidocaine and prilocaine to mixtures of ethyl(hydroxyethyl)cellulose (EHEC) and sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB) or myristoylcholine bromide systems at, or just below, the surfactant concentration found to give a maximum viscosity increase at room temperature. In particular, the myristoylcholine bromide system may be interesting considering its antibacterial properties and biodegradability.
In-situ gel: a study of dental diseases
In-situ forming polymeric gelling systems has become prominent among novel drug delivery system (NDDS) in recent years due to advantages such as sustained and prolonged drug action, improved patient compliance and reduced frequency of administration of the drug in comparison to conventional drug delivery system (DDS). This is a type of mucoadhesive DDS where the polymeric formulation is in sol form before administration and once comes in contact with body fluids; it undergoes gelation to form a gel. The formulation of gel depends upon factors like temperature modulation, pH changes, presence of ions and ultraviolet irradiation from which drug gets released in sustained and controlled manner. Conventional formulation for the treatment of dental diseases has certain drawbacks. A new concept of in situ gel was develop to overcome the shortcoming of conventional formulation which deals with dental diseases. Conventional oral formulations like solution, suspension, and ointments have many disadvantages which result into poor bioavailability of drug in the buccal cavity. In-situ forming polymeric formulation drug delivery systems is in sol form before administration in the body, but once administered, undergoes gelation in-situ to form a gel.
The solution properties of some polyoxyethylene-polyoxypropylene surfactants in nonaqueous solvents
Results obtained with Pluronic polyol homologues in benzene and in dioxane by light-scattering, ultracentrifugal and vapor pressure lowering measurements in addition to data obtained in water and in butyl chloride by light-scattering and ultracentrifugal determinations are described. The systems are examined over a wide range of solute concentrations at about 37C. Considerable difference appears to exist between weight and number-average micellar weight obtained by light-scattering and two methods of measuring vapor pressure lowering of the solutions. Divergence in micellar weight values appears to be less pronounced between the latter technique and ultracentrifugal determinations. Possible micellar configurations of these Pluronic polyols are presented.