HYAFF

The amounts of water absorbed as function of relative water vapor pressure (relative humidity) for HA and its esters are reported in Tables 1-4. HA absorbed the highest amount of water at all humidity levels compared to its esters. The ethyl ester (Hyaff ) absorbs more water than the other two, and the dodecyl ester (Hyaff73) absorbs more water than the benzyl ester (Hyaffll). A small percentage of water absorption hysteresis, between sorption and desorption, was found for the four different materials analyzed. No significant differences in the percentage of hysteresis was found among the HA and the three esters. 

HA > Hyaff7 > Hyaff73 > Hyaffll. It can be noted that the ratio for Hyaffl 1 is much less than that for Hyaff73, although the Hyaffl 1 contains more hydrophilic groups than Hyaff 73. 

The benzyl ester of hyaluronic acid (HYAFF 11) is a highly mucoadhesive polymer which can be processed into microspheres. Such microspheres containing salmon calcitonin were intravaginally administered to rats as a dosage form for the prevention of ovariectomy osteopenia [65]. In recent studies, HYAFF 11-salmon calcitonin microspheres were formulated as single-dose pessaries, resulting in sustained plasma concentrations of calcitonin [67]. 

Bonucci, E., Ballanti, P., Ramires, P.A., Richardson, J.L., and Benedetti, L.M., Prevention of ovariectomy osteopenia in rats after vaginal administration of Hyaff 11 microspheres containing salmon calcitonin, Calcif. Tissue Int., 56 274-279 (1995). 

PCA Hyaluronic acid ethyl ester (HYAFF) PLGA+ thymopentine (Thy)... 

L-PLA, Poly(L-lactide) Hy Hycosinebutylbromid PLGA, Poly(lactide-co-glycolide) (d) Thy, Thymopentine (e) HYAFF, Hyaluronic acid ethyl ether HC, Hidrocortisone (E) DMSO, Dimethylsulfoxide. 

Different drug delivery systems have been proposed for vaginal delivery of peptides and proteins. The first one was a mucoadhesive gel based on polyacrylic acid intended for vaginal administration of insulin [96]. More recently, microparticulate systems such as starch and hyaluronan ester (HYAFF) microspheres have been proposed for vaginal delivery of insulin... 

Rochira, M., et al. 1996. Novel vaginal delivery systems for calcitonin. II. Preparation and characterization of HYAFF microspheres containing calcitonin. Int J Pharm 144 19. 

The production of polymeric HYAFF microspheres loaded with the pharmaceutical is currently performed by solvent emulsion precipitation [4], This process requires the preparation of an emulsion of two immiscible liquids. The polymer and the co-precipitated pharmaceutical can be inactivated or degraded due to the temperature that is required for solvents removing. Moreover, a complete separation of the residual solvents cannot be achieved and a relevant percentage of liquid is retained within the final product. Finally, liquid solvent and antisolvent cannot be recovered. 

Mean particle size, as a function of SAS operating conditions, for the co-precipitation of drug Cx. Precipitator pressure is set equal to 100 bar for all the experimental runs, HYAFF concentration is set equal to 1% w/w. AP/t is the pressure gradient in the loading step. 

Figure 5 In vivo release of drug Ex from HYAFF-11 microspheres (A,V) compared to control release (O).

Comparison between the release profiles obtained with the two formulations is displayed. Since drug Ex has an appreciable solubility in SC CO2, it remains preferably on the suface of the HYAFF particle so the drug release for the two formulation presents no substantial difference. 

Rochira, M., Miglietta, M. R., Richardson, J. L., Ferrari, L., Beccaro, M., and Benedetti, L. (1996), Novel vaginal delivery systems for calcitonin II. Preparation and characterization of HYAFF microspheres containing calcitonin, Int. J. Pharm., 144,19-26. 

Hyalofill Hyaff (hyaluronic acid-based hydrogels) Convatec, S.A. 

HA preparations with various viscoelastic properties promote healing of perforated tympanic membranes [151,152], Films of HA esters, such as HYAFF provided by Fidia, Inc. (Abano Terme, Italy) are used in ear and sinus surgery. These preparations promote wound healing of the tympanic membrane, facilitate re-epithliazation, as well as prevent adhesion between layers of mucous tissues. 

Abbreviations ACP, cross-linked polysaccharide of hyaluronic acid ALAFF, polymer of an ester of alginic acid CBZ, carbamazepine PEG, polyethylene glycol DCM, dichloromethane DMF, dimethylformamide DMSO, dimethyl sulfoxide NMP, A/-methylpyrrolidone P-HBA, p-hydroxybenzoic acid HYAFF-1, hyaluronic acid benzylic ester PEG-PLA, poly(ethylene glycol)-poly(L-lactide) PLGA, poly(lactic-co-glycolide) acid. 

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