Relaxation in aging thermoreversible gels: the role of thermal history

The dynamic heterogeneity in colloidal gels can be tuned by thermal cycles resembling those used in the annealing of molecular amorphous solids.

F FORMULATION DEVELOPMENT AND EVALUATION OF CARBOPOL-INCORPORATED THERMOREVERSIBLE GELS OF PSEUDOEPHEDRINE FOR RECTAL DRUG DELIVERY

Objectives: The present study describes the preparation and evaluation of a Poloxamer 188 (P188)-based thermoreversible gel using Carbopol 934P (C934P) as a mucoadhesive polymer of pseudoephedrine for enhancing the bioavailability and to avoid the first-pass metabolism. Materials and Methods: Five formulations (F1-F5) were prepared using cold method. The prepared gels were characterized by pH, drug content, spreadability, mucoadhesive force, gelation temperature, and drug release profile. Thermoreversibility of P188/C934P gel was demonstrated by rheological studies. The drug-polymer compatibility was studied using Fourier transform infrared (FTIR). Results: The incorporation of carbopol into P188 gel also reduced the amounts of drug released from the gel formulations. FT-IR studies revealed that there are no interactions between the drug and polymers. Drug content of gels was estimated and the results were found to be satisfactory. In vitro dissolution studies revealed a good drug release from the gels. The drug release was higher in formulations F4 and F5 and lower in F1, F2, and F3 formulations. The order of drug release was found to be F5>F4>F3>F2>F1. Conclusion: These findings suggested that developed thermoreversible gels could be used as promising dosage forms to rectal drug delivery for prolonged periods in the management of hemorrhoids.

Photolithographically assembled polyelectrolyte complexes as shape-directing templates for thermoreversible gels

Photolithographically prepared polyelectrolyte complexes (PECs) can serve as shape-directing, sacrificial templates for nonionic thermoreversible gels.

Pharmacokinetics and Pharmacodynamics Evaluation of Tramadol in Thermoreversible Gels

We evaluated pharmacokinetics (PK) and pharmacodynamics (PD) induced by new formulations of tramadol (TR) in thermoreversible gels. The poloxamer- (PL-) tramadol systems were prepared by direct dispersion of the drug in solutions with PL 407 and PL 188. The evaluated formulations were as follows: F1: TR 2% in aqueous solution and F2: PL 407 (20%) + PL 188 (10%) + TR 2%; F3: PL 407 (25%) + PL 188 (5%) + TR 2%; F4: PL 407 (20%) + TR 2%. New Zealand White rabbits were divided into four groups (n=6) and treated by subcutaneous route with F1, F2, F3, or F4 (10 μg·kg−1). PK evaluation used TR and M1 plasma levels. PD evaluation was performed with the measurement of both pupils’ diameters. F2 showed higher TR plasma concentration after 180 minutes and presented lower M1 concentrations at almost all evaluated periods. Areas under the curve (ASC0–480 and ASC0–∞) and clearance of F2 presented differences compared to F1. F2 presented significant correlation (Pearson correlation) between the enhancement of TR and M1 concentrations and the decrease of pupil size (miosis). Thus, F2 was effective in altering pharmacokinetics and pharmacodynamics effects of TR.