Carbopol properties

Bonacucina, G., Martelli, S., Palmieri, G.F. (2004). Rheological, mucoadhesive and release properties of Carbopol gels in hydrophilic cosolvents. International Journal of Pharmaceutics, 282, 115-130. 

Li, S., et al. 2003. Effect of HPMC and Carbopol on the release and floating properties of gastric floating drug delivery systems using factorial design. Int J Pharm 253 13. 

A study compared the buccal mucoadhesive properties for different polymeric films that differed in their cross-linking status [91]. Synthetic (Carbopol 971P, PCP), semisynthetic (SCMS), and natural carrageenan (X-type) were analyzed for their mucoadhesive properties using a TA-XT2i texture analyzer. 

From a formulative point of view, it is important to take into consideration that the base in which liposomes are incorporated could also affect the drug delivery profile as well as the interactions between the liposomes and skin structures. The effect of formulation bases on dyphylline skin permeation from liposomes was examined by Touitou et al. [9]. In this work the effect of four bases for dyphylline liposomes (polyethylene glycol (PEG), carbopol gel, a PEG-enhancer base, and water) was studied. With these bases, the lowest skin permeation flux and a superior skin partitioning of liposomal dyphylline were reported for the PEG base, suggesting that this base favored dyphylline accumulation within the skin. A number of liposomes are currently marketed by cosmetic raw material companies for incorporation in different bases to obtain final products. It is important to keep in mind that the delivery properties of the final formulation could be altered by the vehicle used and should be tested to confirm any performance characteristics claimed. 

Takeuchi, H., Matsui, Y., Yamamoto, H., and Kawashima, Y. Mucoadhesive properties of carbopol or chitosan-coated liposomes and their effectiveness in the oral administration of calcitonin to rats. J. Contr. Rel. 86 235—242, 2003. 

Takeuchi H, Yamamoto H, Kawashima Y (2001) Mucoadhesive nanoparticulate systems for peptide drug delivery. Adv Drug Del Rev 47( 1 ) 39—54 Takeuchi H, Matsui Y, Yamamoto H, Kawashima Y (2003) Mucoadhesive properties of carbopol or chitosan-coated liposomes and their effectiveness in the oral administration of calcitonin to rats. J Control Rel 86(2-3) 235-242 Takeuchi H, Matsui Y, Sugihara H, Yamamoto H, Kawashima Y (2005a) Effectiveness of submicron-sized, chitosan-coated liposomes in oral administration of peptide drugs. Int J Pharm 303(1-2) 160-170... 

Combining thermal- with pH-dependent gelation, Kumar et al. [86] developed a combination of methylcellulose 15% and carbopol 0.3%. This composition exhibited a sol-to-gel transition between 25 and 37 °C with a pH increase from 4 to 7.4 [203], A possible mechanism for the thermal effect could be the decrease in the degree of the methylcellulose hydration, while the polyacrylic acid can transform into a gel upon an increase in pH due to the buffering properties of the tear fluid [1]. 

Barry BW and Meyer MC. The rheological properties of carbopol gels I. Continuous shear and creep properties of carbopol gels. Int. J. Pharm. 1979 2 1-25. 

In the 1980s, Machida and Nagai evaluated spray dosage forms based on hydroxypropyl cellulose (HPC) for the delivery of beclomethasone to treat recurrent and multiple apthae. Previously a double-layered tablet of HPC and Carbopol 934P was introduced in the market for the treatment of apthous stomatitis. " Bouckaert, Lefebvre, and Remon " tested buccal tablets of miconazole based on modified starch-polyacrylic acid mixtures. Although these tablets showed different mucoadhesion properties in vitro, no significant differences in the salivary content of miconazole could be observed in human volunteers. 

To increase the residence time in the nasal mucosa, a bioadhesive formulation may be one of the most reasonable approaches. In fact, microspheres containing bioadhesive polymers such as starch, albumin, and Sephadex with a particle size of 40-60 pm have been found to be cleared from the nasal cavity much more slowly than solutions. Starch microspheres improved the nasal absorption of insulin, with synergistic effects of some absorption enhancers in sheep. In another paper, dry powder containing starch and Carbopol 974P showed significantly higher bioavailability after nasal administration than the formulation without Carbopol. ° Chitosan, already mentioned above, also has a bioadhesive property and is found to be useful as a potent absorption enhancer for nasal peptide delivery. Other bioadhesive polymer systems,... 

Carnali JO, Naser MS. The use of dilute solution viscosity to characterize the network properties of carbopol microgels. Colloid Polym Sci 1992 270 183-193. 

Unlii N, Ludwig A, van Ooteghem M, et al. Formulation of carbopol 940 ophthalmic vehicles, and in vitro evaluation of the influence of simulated lacrimal fluid on their physico-chemical properties. Pharmazie 1991 46 784-788. 

Brohede U, Bramer T, Edsman K, et al. Electrodynamic investigations of ion transport and stractural properties in drug-containing gels dielectric spectroscopy and transient current measurements on catanionic carbopol systems. J Phys Chem B 2005 109 15250-15255. 

In a more phenomenologically oriented study [396], Newtonian liquids (p < 19 mPa s), non-Newtonian liquids (pseudoplastic e.g. CMC), several high viscosity liquids with viscoelastic properties and Carbopol and xanthane as fluids with yield stress were used. In gassed conditions three flow ranges could be distinguished ... 

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