The effect of thymoxamine on histamine induced bronchospasm in man

The airways response to phenylephrine after blockade of alpha and beta receptors in extrinsic bronchial asthma

“…Alpha receptor blocking drugs have been known to inhibit histamine hyperreactivity ofthe airways in asthmatic subjects (Kerr et al, 1970;Bianco et al, 1972;Gaddie et al, 1972) and in our experience histamine hyper-reactivity is consistently Airways response to phenylephrine 447 associated with alpha receptor activity and contrasts with methacholine induced bronchoconstriction which is not inhibited by thymoxamine (personal observations).…”

Α‐adrenoceptor Blocking Drugs in Asthma

“…A similar effect of thymoxamine in the bronchial smooth muscle would explain the results reported. In addition, thymoxamine inhibits histamine, allergen and exercise induced bronchoconstriction (Bianco, Griffin, Kamburoff & Prime, 1972;Patel & Kerr, 1975;Patel, Kerr, MacDonald & McKenzie, 1976) and this effect of thymoxamine is possibly mediated by its ability to increase cyclic AMP formation. These observations of ca-adrenoceptor blocking drugs in asthma suggest that they may have a place in management of chronic labile airways obstruction.…”

“…Methods et-adrenoceptors are present in mammalian lungs and pharmacological stimulation of these receptors can cause bronchoconstriction (Everitt & Cairncross, 1969; Prime, Bianco, Griffin & Kamburoff, 1972;Simonsson, Svedmyr, Skoogh, Andersson & Bergh, 1972). This airways response to ot-adrenoceptor stimulation is greatly enhanced in asthmatic patients and it is suggested that the increased bronchial a-adrenoceptor activity in asthma may result from a diminished 13-adrenoceptor responsiveness to catecholamines (Patel & Kerr, 1973).…”

Alpha-Adrenergic Blocking Agents in the Treatment of Asthma

“…In 1972 it was shown that when thymoxamine was given intravenously to six asthmatic patients (30) or orally to four normal subjects (31), inhaled histamine-induced broncho constriction was reduced. Unlike phenoxybenzamine, which has also been shown to protect against histamine-induced bronchial narrowing (25), thymoxamine is almost devoid of antihistaminic action, and it is suggested that its mode of action is via a-adrenergic receptors in bronchial smooth muscle (31). The bronchodilating action of thymoxamine has been supported by Patel and Kerr (32) when they found that administration of intravenous thymoxamine inhibited allergen-provoked bronchospasm, and, in some cases, inhaled thymoxarnine was effective.…”