Chemical development of astemizole-like compounds

A clinical drug library screen identifies astemizole as an antimalarial agent

The high cost and protracted time line of new drug discovery are major roadblocks to creating therapies for neglected diseases. To accelerate drug discovery we created a library of 2,687 existing drugs and screened for inhibitors of the human malaria parasite Plasmodium falciparum. The antihistamine astemizole and its principal human metabolite are promising new inhibitors of chloroquine-sensitive and multidrug-resistant parasites, and they show efficacy in two mouse models of malaria.

Molecular pharmacological aspects of histamine receptors

In this article, we review the recent developments in the field of histamine research. Besides the description of pharmacological tools for the H1, H2 and H3 receptor, specific attention is paid to both the molecular aspects of the receptor proteins, including the recent cloning of the receptor genes, and their respective signal transduction mechanisms.

Involvement of histamine in the control of the waking state

Available evidence indicates that histamine (HA) plays a neuroregulatory role in the waking state. Support for this proposal is provided by electrophysiological, lesion and pharmacological studies, as well as by fluctuations of HA levels according to a circadian pattern. Thus, 1) HA-containing neurons unit activity changes dramatically as a function of behavioral state across the sleep-wakefulness continuum, from 2.3 spikes/sec during active waking to virtual silence during slow wave sleep and REM sleep; 2) HA levels reach a minimum during the dark phase followed by an increase during the light period in rats kept under controlled environmental conditions; in addition histidine decarboxylase and HA-N-methyl-transferase activities are higher during darkness; 3) lesions or cooling of the posterior hypothalamus in the area where HA-immunoreactive neurons are located gives rise to a state of somnolence or hypersomnia; 4) 2-thiazolylethylamine, the predominantly H1-receptor agonist and thioperamide, the H3-receptor antagonist increase wakefulness in laboratory animals, while the HA synthesis inhibitor a-fluoromethylhistidine, the H1-receptor antagonists mepyramine, diphenhydramine and chlorpheniramine, and the H3-receptor agonist (R)-a-Me-histamine produce opposite effects.

Levocabastine: Pharmacological profile of a highly effective inhibitor of allergic reactions

Levocabastine, selected from a series of cyclohexylpiperidine derivatives protects rats from compound 48/80-induced anaphylactic shock for at least 16 h at the oral dose of 0.0015 mg/kg. At the same dose histamine skin reactions and at slightly higher doses passive cutaneous anaphylactic reactions are inhibited. Blockade of passive cutaneous anaphylactic reactions is obtained with levocabastine, despite absence of peripheral serotonin antagonism and any other known non-specific action that may facilitate inhibition of passive anaphylaxis. In dogs allergic reactions are inhibited at oral doses 40 times lower than ketotifen. In guinea-pigs orally and topically administered levocabastine are remarkably effective against allergic conjunctivitis.