N-acetyl cysteine versus chlorhexidine mouthwashes in prevention and treatment of experimental gingivitis: a randomized, triple-blind, placebo-controlled clinical trial.

OBJECTIVES: To compare the efficacy of N-acetyl cysteine (NAC) mouthwash with chlorhexidine (CHX) in prevention and treatment of experimental gingivitis MATERIALS AND METHODS: Sixty subjects were assigned randomly and blindly into one of three equal groups: NAC, CHX, or placebo group. The study was conducted in two stages: preventive and treatment substudies. Professional prophylaxis was performed ahead of starting the preventive substudy. Then, the subjects were instructed to stop oral hygiene practices and begin rinsing twice/day with 15 ml of the assigned mouthwash (1.25% NAC, 0.2% CHX, or inert base). Plaque index (PI), gingival index (GI), and papillary bleeding index (PBI) were measured at baseline, 7, 14, and 21 days. The treatment substudy started on day 21 in which the subjects in the placebo group (now with established experimental gingivitis) were assigned to NAC (n = 10) or CHX (n = 10); the abovementioned indices were measured at 28 and 35 days. Efficacy of these interventions was compared. RESULTS: All groups accumulated plaque and developed some degree of gingivitis: full-blown in the placebo group and remarkably mild in the CHX group. NAC had slight preventive properties at days 14 and 21. In the treatment substudy, CHX was associated with remarkable reduction in plaque and gingivitis while NAC resulted in insignificant reductions. CONCLUSIONS: 1.25% NAC is marginally effective in prevention and treatment of experimental gingivitis. CLINICAL RELEVANCE: When compared with the placebo, NAC showed promising preventive and treatment effects of gingivitis that deserve further development and studies. TRIAL REGISTRATION: ISRCTN31352091.

Basal level insulin delivery: in vitro release, stability, biocompatibility, and in vivo absorption from thermosensitive triblock copolymers.

The major goal of this study was to develop the biodegradable and biocompatible thermosensitive polylactic acid-polyethylene glycol-polylactic acid triblock copolymer-based delivery systems for controlled release of basal level insulin for a longer duration after single subcutaneous injection. Insulin was dispersed into aqueous copolymer solutions to prepare the delivery system. The in vitro release profile of insulin from delivery systems was studied at 37°C in phosphate-buffered saline. Stability of released insulin was investigated using circular dichroism, differential scanning calorimetry, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and skin histology were used to determine the in vitro and in vivo biocompatibility of the delivery systems, respectively. Streptozotocin-induced diabetic rat model was used to study the in vivo absorption and bioactivity of insulin. In vitro release studies indicated that the delivery systems released insulin over 3 months in structurally stable form. The delivery systems were biocompatible in vitro and in vivo. In vivo absorption and bioactivity studies demonstrated elevated insulin level and corresponding decreased blood glucose level in diabetic rats. Thus, the delivery systems released insulin at a controlled rate in vitro in conformationally and chemically stable form and in vivo in biologically active form up to 3 months.

Controlled delivery of basal insulin from phase-sensitive polymeric systems after subcutaneous administration: in vitro release, stability, biocompatibility, in vivo absorption, and bioactivity of insulin.

The purpose of this study was to investigate the phase-sensitive delivery systems (D,L-polylactide in triacetin) for controlled delivery of insulin at basal level. The effect of varying concentration of zinc, polymer, and insulin on the in vitro release of insulin was evaluated. Stability of released insulin was investigated by differential scanning calorimetry, circular dichroism, and matrix-assisted laser desorption/ionization time of flight mass spectrometry. In Vivo insulin absorption and bioactivity were studied in diabetic rats. In vitro and In Vivo biocompatibility of delivery systems were evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and skin histology, respectively. Extended release profiles of insulin for 2, 4, and 8 weeks from delivery systems containing 20%, 30%, and 40% (w/v) polymer concentration was observed. A ratio of 1:5 insulin hexamer to zinc was shown to be optimum. Physical and chemical stability of released insulin was greatly conserved. In Vivo studies demonstrated controlled release of insulin with reduction in blood glucose for approximately 1 month. In vitro and In Vivo studies demonstrated that the delivery system was biocompatible and controlled the delivery of insulin for longer durations after single subcutaneous injection.

Smart polymer based delivery systems for peptides and proteins.

Biodegradable polymeric systems represent promising means for delivering many bioactive agents, including peptide and protein drugs. The importance of these systems grew with the advancement in the understanding of peptide and protein pharmacology as well as the ability to mass-produce these compounds. Some polymers undergo sol-gel transition once administered. In situ gel formation happens in response to one or a combination of two or more stimuli. These stimuli include UV-irradiation, pH change, temperature change, and solvent exchange. These smart polymeric systems have several advantages over conventional methods, such as ease of manufacturing, ease of administration, biodegradability, and the ability to alter release profiles of the incorporated agents. In the past few years, an increasing number of in situ gel-forming systems have been investigated and many patents for their use in various biomedical applications, including drug delivery, have been reported. In this article, we introduce the different strategies that have been developed and patented for the use of smart polymers in delivering peptide and protein drugs. The advantage, disadvantages, possibilities, and limitations of each of the smart polymer systems have been discussed.

Poly lactic acid based injectable delivery systems for controlled release of a model protein, lysozyme.

The objective of this study was to evaluate the critical formulation parameters (i.e., polymer concentration, polymer molecular weight, and solvent nature) affecting the controlled delivery of a model protein, lysozyme, from injectable polymeric implants. The conformational stability and biological activity of the released lysozyme were also investigated. Three formulations containing 10%, 20%, and 30% (w/v) poly lactic acid (PLA) in triacetin were investigated. It was found that increasing polymer concentration in the formulations led to a lower burst effect and a slower release rate. Formulation with a high molecular weight polymer showed a greater burst effect as compared to those containing low molecular weight. Conformational stability and biological activity of released samples were studied by differential scanning calorimeter and enzyme activity assay, respectively. The released samples had significantly (P < 0.05) greater conformational stability and biological activity in comparison to the control (lysozyme in buffer solution kept at same conditions). Increasing polymer concentration increased both the conformational stability and the biological activity of released lysozyme. In conclusion, phase sensitive polymer-based delivery systems were able to deliver a model protein, lysozyme, in a conformationally stable and biologically active form at a controlled rate over an extended period.