Gelatin aldehyde links

The capsule shells are, in essence, delivery vehicles designed to contain mainly powders or multiparticulates. Materials contained within the capsules may dissolve immediately but may also be coated to impart MR performance. In addition to the dietary advantages of HPMC capsules, they typically contain less residual moisture so, the materials contained within will be exposed to less moisture. ° Furthermore, the capsule is designed to quickly dissolve and thus release its materials within a matter of minutes. Gelatin cross-links if exposed to aldehydes, which hinders dissolution of the gelatin capsule. HPMC capsules are much less susceptible to cross-linking. 

Gelatin and albumin nanoparticles have been prepared through desolvation of the dissolved macromolecules by either salts (e.g., sodium sulfate or ammonium sulfate) or ethanol [179-182], This is, in principle, similar to a simple coacervation method. The particles can then be insolubilized through cross-linking with an optimum amount of aldehydes. These phase separation methods avoid the use of oils as the external phase. 

Fig. 5. Relation between the average molecular weight between cross-links, Mc, and the volume fraction of gelatinized collagen (gelatin), v2. The swelling agent is 0.19 mol/1 citric acid - phosphate buffer solution, pH 7.4 at 80 °C. Experimental data obtained after cross-linking with various aldehydes solid circles, formaldehyde open circles, glutaraldehyde squares, glyoxal. The curve is predicted by Eq. (2) with X = 0.52 0.04 [38]...

The second issue is the slow release in the body of the cross-linking aldehydic reagents used to cross-link and stabilize the gelatin microparticles. This will occur slowly in vivo as the gelatin matrix itself dissociates and goes into solution. However, the effect of low level, slow, localized, release of glutaraldehyde over a period of time has not been evaluated clinically and the issue remains open for discussion. 

Hypromellose does not react with aldehydes or other agents that cause cross-linking of gelatin. Hypromellose capsules start to release their contents slightly slower than gelatin ones because of the slower rate of diffusion of water through the shell walls. However, once dissolution has commenced, the rates are similar and the results are comparable. ... 

Apart from the environmental factors, chemical compounds also induce cross-linking of gelatin. Supporting this is the mechanism in Fig. 5, which highlights the role of external aldehydes. Among the low molecular weight aldehydes, formaldehyde is most important as it is released in dosage forms from plasticizers and preservatives, fats, and polyethylenated... 

Milch (1964) obtained infrared spectra on aqueous solutions of some aliphatic and aromatic aldehydes. Saturated compounds which are capable of acting as interchain cross-linking agents for the polypeptide chains of either gelatin sols or native... 

Tengroth, C., Gasslander, U., Andersson, F.O., Jacobsson, S.P. Cross-linking of gelatin capsules with formaldehyde and other aldehydes An FTIR spectroscopy study. Pharm. Dev. Technol. 2005, 10(3), 405-412. 

Gelatin used as wall material in complex coacervation needs hardening with glutaraldehyde or formaldehyde. Both aldehydes are considered toxic to humans and must be carefully used. For this reason, several studies have been carried out to find safer cross-linking agents such as transglutaminase, tannic acid, and glycerol (Xiao et al., 2014). 

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