The difference in effect of predosing with antiallergic compounds between the rat PCA model and the monkey asthma model. Comparison of the effects of PRD-92-Ea and disodium cromoglycate

Studies on a new antiallergic pyridinecarboxamide TA-5707F and its sodium salt (TA-5707). I. Inhibition of IgE-induced passive cutaneous anaphylaxis (PCA) in rats

Effects of TA-5707F [6-methyl-N-(1H-tetrazol-5-yl)-2-pyridinecarboxamide] and its sodium salt (TA-5707) on IgE-induced homologous PCA in rats were investigated. 1. Both TA-5707 and TA-5707F were found to be orally effective inhibitors of rat PCA. Maximum activity by oral administration was obtained when they were administered 5 min before the challenge. Their ID50's under these conditions were both approximately 1 mg/kg. Administration 5 min after the challenge was no longer effective. 2. TA-5707 was also effective by intravenous administration, and its ID50, ca. 0.1 mg/kg, was less than that of disodium cromoglycate (DSCG). 3. The PCA-inhibitory activity of TA-5707 was not affected by adrenalectomy and adrenomedullectomy. 4. Daily administration of TA-5707 or TA-5707F for 8 days did not induce drug tolerance. 5. Tachyphylaxis and cross-tachyphylaxis were observed when the PCA-inhibitory activities of TA-5707 and DSCG were tested after intravenous pretreatment with a large dose (ca. 30 times the ID50) of either drug, but not after oral pretreatment with a therapeutic dose of TA-5707 or TA-5707F.

Cromolyn sodium: a review

Cromolyn is a white crystalline powder which is poorly absorbed from the gastrointestinal tract. Its therapeutic value lies in its functions as an inhaled or topically applied agent. Cromolyn has been approved in the United States for asthma therapy since 1973. It was marketed at that time as a drug to reduce the corticosteroid requirements of severe asthmatics. It clearly did not live up to that claim. Initial enthusiasm for cromolyn was replaced by disillusionment. In the last few years, investigators have taken another look at cromolyn and have a renewed interest in it. Cromolyn's mechanisms of action remain only partially understood. It appears to block allergic mediator release from certain mast cells. It may also decrease bronchial hyperreactivity. The frequency of drug toxicity at customary dosages is extremely low. Adverse effects tend to be mild, short-lived and without sequelae. Currently, cromolyn is a first line therapy for mild to moderate asthma requiring chronic treatment. It is also of proven efficacy in the treatment of allergic rhinitis, allergic conjunctivitis and vernal keratoconjunctivitis.

The gastrointestinal absorption of PRD-92 Ea, a new anti-allergy drug

1 The absorption of PRD-92 Ea, a new anti-allergy drug, was studied in volunteer subjects. 2 The 14C-labelled drug was administered orally and the radioactivity measured in plasma, urine and faeces. 3 Mean peak plasma concentration was 3.3 micrograms/ml, with a concentration of over 1 micrograms/ml maintained 4 h after administration. 4 The mean plasma half-life (T 1/2) was 114 min. 5 The mean percentage recovery in the urine was 9.5%. 6 Oral administration leads to significant and sustained plasma concentrations, and the oral route should be suitable for drug evaluation in clinical practice.