Triptans are a family of tryptamine-based drugs used in the treatment of migraines. Triptans are generally effective, with few side effects, also safe dose are well determined. And, pharmacokinetic properties of triptans are simple and continuous. On the other hand, the medicinal effect duration of triptans is very short compared to the duration of migraines. The problems appear when triptans are taken orally ㅡ the bioavailability of triptans is reduced by the digestive system, the blood drug content reduces rapidly through time and there is a possibility of gastrointestinal disorder, etc. These are improved and the medicinal effect is extended with drug application using a patch.
To improve the side effects ㅡ of pain and tingling on the area where the patch is attached, itching, hot flushes, discomfort, etc. ㅡ the common gel patch is prepared in hydrogel form. The polymer of matrix which makes up the hydrogel uses PVA, which has non-toxicity, non-carcinogenicity, biocompatibility, high mechanical properties, easy process, high water uptake, etc. PEG is used as an additive to induce inter/intra hydrogen bonding of the PVA. In addition, to accelerate micro phase separation between PVA chains, liquid nitrogen at very low temperature is used. The FT-IR is used to make sure the drug is contained in prepared hydrogel; WAXD is used to analyze the degree of crystallinity of prepared hydrogel depending on the PEG content. To investigate the role of PEG, which is added to the PVA aqueous solution and has a very low temperature freezing effect for prepared hydrogel, the measurements of contact angle, water uptake, and tensile strength are conducted. Drug release test of the almotriptan PVA hydrogel patches are conducted.
In the FT-IR analysis, the absorption bands of PVA, PEG, and almotriptan were found; in the WAXD analysis, crystallinity was widened with increasing PEG content. The surface energy increases with a smaller contact angle, in other words, the water content is increased with the PEG content. In addition, the water uptake ability and tensile strength are increased with increasing PEG content. All these effects are due to the formation of hydrogen bonding between PVA and the crystallization zone. In the drug release test, the higher the content of PEG, the higher the water absorption of hydrogel, as mentioned above. Thus, the amount of drug released is increased because hydrogel in which the PEG content is higher is more swollen at the time of drug release.
In this study, drug release of hydrogel prepared with the addition of 10 wt% PEG is good. In addition, until the 2nd hour, about 60 % of the total amount of drug is released, and even until 24th hour, the release of the drug continues in hydrogel containing 10 wt% PEG. Thus, the prepared hydrogel patch is suitable as a transdermal formulation for a triptan second dose administration in patients with recurrent migraine within 24 hours after administration of the first dose of triptan.