Polyacrylic acid gel

Polyurethane Hydrogel Cross-Linked Polyacrylamide Gels Cross-Linked Polyacrylic Acid Gels... 

FIGURE 8.5 Effects of ions on polyacrylic acid gels. 

Morimoto, K., T. Iwamoto, and K. Morisaka. 1987. Possible mechanisms for the enhancement of rectal absorption of hydrophilic drugs and polypeptides by aqueous polyacrylic acid gel. J Pharmacohiodyn 10 85. 

Morimoto, K., et al. 1985. Effect of non-ionic surfactants in a polyacrylic acid gel base on the rectal absorption of [Asul,7]-eel calcitonin in rats. J Pharm Pharmacol 37 759. 

Our observation that CMC lacked the ability to increase the systemic activity of desmopressin is consistent with the findings of Morimoto et al. (13), who reported that 1% CMC failed to enhance intranasal absorption of insulin, whereas, another bioadhesive agent, polyacrylic acid gel, effectively promoted insulin absorption. As the mechanism by which bioadhesives such as polyacrylic acid gel and carboxypolymethylene promote intranasal peptide absorption remains unclear, it is not possible to explain the demonstrated lack of similar activity by CMC. 

Morimoto et al. [64] studied the nasal absorption of insulin using polyacrylic acid gel. When insulin was formulated with 0.1% w/v polyacrylic acid gel base (pH 6.5), the maximum hypoglycemic effect was seen 30 min following intranasal administration in 1% w/v gel base, however, it took lh to reach the maximum effect. There was no effect of the pH (4.5, 6.5, and 7.5) of 0.1% w/v polyacrylic acid gel on the extent of nasal absorption. 

Polyacrylic acid aqueous gel enhances the absorption of calcitonin after nasal as well as rectal administration. When [Asul,7]-eel calcitonin (lOU/kg) was administered nasally in polyacrylic acid gel at a concentration of 0.1% w/v, a prominent hypocalcemic effect was seen in the first 30min. Nasal administration of [Asul,7]-eel calcitonin in saline had no hypocalcemic effect at the same dose when given by the nasal route. In addition to this, the effect of [Asul,7]-eel calcitonin in the dose range of 1-10 U/kg has also been studied. The resulting data showed that a rapid reduction in plasma calcium concentrations can be achieved at doses of 5 and 10 U/kg however, at doses of 1 U/kg only a small reduction in the plasma calcium concentration was observed, suggesting that polyacrylic acid gel can be used for the intranasal administration of peptides such as calcitonin. The possible side effects, however, were not known at the time the study was performed [76-78],... 

Morimoto, K., Morisaka, K., and Kamada, A. (1985), Enhancement of nasal absorption of insulin and calcitonin using polyacrylic acid gel,/. Pharm. Pharmacol., 37,134-136. 

Morimoto K, Morisaka K. In vitro release and rectal absorption of barbital and aminopyrine from aqueous polyacrylic acid gel. Drug Dev Ind Pharm 1987 13(7) 1293-1305. 

In this equation there are three unknowns the molar swelling ratio Q, the effective degree of neutralization Ocff and the number of active-free-ions-per-monomer Pcff. Swelling ratio Q can be measured experimentally. The effective degree of neutralization tteff can be found by solving equation (1). Tlie parameter f can be found by fitting the experimental data at one experimental condition and it was found f=l/2 for polyacrylic acid gel. If Q, Oe and f are known, equation (33) can be solved for Peff and salt absorption then can te deuced from pe ... 

Table I. Salt Absorption of Polyacrylic Acid Gels (a) Gels with crosslink density of 3.5x10 (mole/cm )...

Figure 6. pH in polyacrylic acid gels and their solution as a function of degree of neutralization. 

A copper cross-linked polyacrylic acid gel, containing titanium dioxide particles, has been shown to swell under UV light and contract again in the dark [132]. A similar system with silver-coated titanium dioxide has also been described [133]. The volume change is large but the response time is hundreds of minutes. 

---