19 julho 2008

Arginina gel: estabilidade de uma preparação semisólida para uso tópico


PHARMACEUTICAL DEVELOPMENT AND STABILITY STUDIES OF A TOPICAL GEL CONTAINING L-ARGININE

H. Gonçalves*, A. Melo Gouveia*, H.M. Ribeiro**, A. Salgado**, A. Silva**, M. A. Duarte**, A.J. Almeida**

*Instituto Português de Oncologia de Lisboa, Portugal; **iMed.UL, Faculdade de Farmácia da Universidade de Lisboa, Portugal.

Email: humberto.mestrado@gmail.com

Background: Anal fissures cause pain, blood loss and discomfort, and have serious consequences on the quality of life of oncology patients, mainly as a side effect of radiation treatment. It is known that this pathology is related to ischemia of the anal region. Usual treatment consists on improving blood circulation and inducing relaxation of the sphincter. Current treatments, such as surgery, diet and topical preparations of vasodilators such as
nitroglycerine have shown relative efficacy and relevant side effects. The use of a topic preparation of L-arginine has the rationale that this drug can be locally metabolised to nitric oxide, and thus act as a vasodilator with reduced systemic effects. The objective of this work is the development and short term stability test of a topical gel with L-arginine to be compounded on named patient basis inside hospital pharmacy.

Methods: Based on well established pharmaceutical technology information, several gelling agents and concentrations were evaluated (hydroxypropylmethylcelulose, hydroxiethyl-celulose
and carbomer). All were assessed for several characteristics such as organoleptic properties, pH, rheology, osmolarity and microbiology testing. On the chosen formulation, the same characteristics were assessed for a period of 2 months, in order to provide some stability data.

Results: Out of 9 tested formulations, one was considered suitable, using hydroxyethylcellulose as gelling agent. The resulting product is a transparent gel with adequate viscosity. On this formulation the assessment was repeated after one and two months. Organoleptic characteristics remained stable, pH showed slight reduction (5,8 to 5,71 after 2 months). Rheology and osmolarity remained unchanged.

Conclusions: According to the assessed parameters, the formulation of L-arginine gel shows a 60 day stability in terms of organoleptic parameters, pH, rheology and osmolarity. Further work will include development of an assay method and clinical tests. It is expected that assay data will be available by January 2008.

Reference: 13th EAHP Congress, Maastricht, the Netherlands, 27-29 February 2008

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