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Biomedical subjects

A Figueiredo

Publications and source records attributed to A Figueiredo.

6 recordsLinked to original sources
PubMed1992

Photosensitivity to piroxicam: absence of cross-reaction with tenoxicam.

We studied 2 groups of patients. One group of 10 patients had a photosensitive eruption to piroxicam. Another group of 24 patients had positive patch test reactions to thimerosal and thiosalicylic acid and had never taken piroxicam or tenoxicam. Patients were patch tested with thimerosal 0.1% pet., thiosalicylic acid 0.1% pet., salicylic acid 2.0% pet., piroxicam 1 and 5% pet. and tenoxicam 1 and 5% pet. Photopatch tests were also performed with piroxicam and tenoxicam. All 10 patients with photosensitivity to piroxicam had positive patch tests to thimerosal and thiosalicylic acid and 9 of them had positive photopatch tests to piroxicam. 20 out of 24 patients with positive patch tests to thiosalicylic acid also had positive photopatch tests to piroxicam. All the patients tested with salicyclic acid were negative. Out of the 29 patients with positive photopatch tests to piroxicam, none reacted to tenoxicam. In countries with a high incidence of contact sensitivity to thimerosal/thiosalicylic acid, the use of piroxicam should be avoided and replaced by tenoxicam, a drug without reported photosensitivity.

Adult↗
PubMed1992

Tiaprofenic acid-induced photohemolysis in vitro is inhibited by nimesulide.

The effect of nimesulide on red blood cell (RBC) lysis photosensitized by tiaprofenic acid was investigated. The tiaprofenic acid-induced photohemolysis rate was enhanced by exposure to oxygen but lysis was also observed under anaerobic conditions. Photohemolysis was decreased by reduced glutathione (GSH) and reduced even more by butylated hydroxyanisole (BHA); sodium azide, superoxide dismutase and mannitol did not show a significant effect. Nimesulide did not cause any RBC lysis and inhibited this action of tiaprofenic acid by 20-30%, depending on the concentration of nimesulide and the intensity of ultraviolet A light. The protective effect of GSH, but not of BHA, was increased by nimesulide. Our findings suggest that free radicals are generated in this in vitro model of phototoxicity and are involved in the photoaggression to the red blood cell membrane, this effect being partially inhibited by nimesulide.

Anaerobiosis↗
PubMed1992

[Primary hyperparathyroidism].

Primary hyperparathyroidism due to a solitary adenoma of the right inferior parathyroid gland was diagnosed in a 60 year old female, presenting a 4 year complaint of progressive disabling bone and joint pain. The diagnostic follow-up used in this case, including the imaging techniques, the clinical features and the medical and surgical management are presented and discussed.

Adenoma↗
PubMed1990

Mechanism of action of doxepin in the treatment of chronic urticaria.

The present study examined 15 patients previously resistant to conventional antihistamines, in which doxepin at doses in the range of 50-75 mg/day was shown to be effective in treatment of chronic urticaria and without significant adverse side effects. However, some controversy remains about its mechanism of action in this particular disease. The aim of the present study was to examine the muscarinic, H1 and H2 blocking activity of doxepin. The following methods were used: a) gastric acid hypersecretion induced by histamine and carbachol in the pylorus-ligated rat preparation; b) contractile dose-response curves to histamine and carbachol in the guinea pig ileum; c) dimaprit-stimulated guinea pig atrium in vitro. pA2 values were determined for atropine, mepyramine, cimetidine and doxepin. As regards histamine, doxepin (50 mg/kg, po) increased gastric pH and decreased secretion volume, gastric acid concentration and total acid output; with carbachol, doxepin weakly antagonized those values. In the ileum, doxepin competitively antagonized carbachol (pA2 = 7.08) and histamine (pA2 = 9.72); pA2 values for atropine and mepyramine against carbachol and histamine were 9.11 and 8.82, respectively. In the atria, the dose-response curve to dimaprit was also competitively displaced by cimetidine (pA2 = 6.69) and doxepin (pA2 = 6.00). Doxepin displayed a very high affinity for H1 histamine receptor, being 8-fold more potent than mepyramine. Doxepin showed significant H2 blocking activity which was 5 times less potent than that of cimetidine. Doxepin competitively antagonized carbachol in the guinea pig ileum, and was 107 times less potent than atropine. The combined H1, H2 and muscarinic blocking activities of doxepin may contribute towards explaining its clinical efficacy in the treatment of chronic urticaria.

Adult↗