In vitro and in vivo characterization of MDL 105,212A, a nonpeptide NK-1/NK-2 tachykinin receptor antagonist.

Abstract

We have identified and characterized a novel, potent, nonselective tachykinin receptor antagonist, MDL 105,212A [(R)-1-[2-[3-(3,4- dichlorophenyl)-1-(3,4,5-trimethoxybenzoyl)-pyrrolidin-3-yl] -ethyl]- 4-phenylpiperidine-4-carboxamide, hydrochloride]. The compound binds with low nanomolar affinity and species specificity to human NK-1 and NK-2 receptors as well as to guinea pig NK-3 receptors. In vitro functional assays are consistent with potent competitive antagonism of substance P-(SP) or neurokinin A-(NKA) induced [3H]-inositol phosphate accumulation in NK-1 or NK-2 monoreceptor cell lines with pA2 values of 8.19 and 8.67, respectively. Its ability to inhibit SP, NKA and capsaicin-mediated respiratory effects was examined in guinea pigs in vivo. MDL 105,212A attenuated SP-induced airway plasma protein extravasation (ED50 = 0.20 mg/kg, i.v.), NKA-induced respiratory collapse (ED50 = 5 mg/kg, i.v) and inhibited capsaicin-induced increases in pulmonary insufflation pressure (ED50 = 0.5 mg/kg, i.v.). Conscious guinea pigs responded to capsaicin aerosol exposure with dyspnea, coughs and gasps (significant respiratory events) and plasma protein extravasation. MDL 105,212A inhibited these responses in a dose-dependent manner after i.v. (ED50 = 5 mg/kg) or oral (ED50 = 50 mg/kg) administration. These data suggest that MDL 105,212A is a potent NK-1 and NK-2 receptor antagonist based on in vitro activity and its ability to inhibit SP and NKA mediated respiratory effects in vivo after exogenous administration or endogenous release and hence may be a useful therapeutic agent in neuroinflammatory disorders such as asthma in which a role for both tachykinins in the pathogenesis of the disease has been postulated.

• Authors: E M Kudlacz, S A Shatzer, R W Knippenberg, D E Logan, M Poirot, P L van Giersbergen, T P Burkholder
• Journal: The Journal of pharmacology and experimental therapeutics (J Pharmacol Exp Ther) Vol. 277 Issue 2 Pg. 840-51 (May 1996) ISSN: 0022-3565 [Print] United States
• PMID: 8627566 (Publication Type: Journal Article)

Chemical References

• Inositol Phosphates
• MDL 105212A
• Neurokinin-1 Receptor Antagonists
• Piperidines
• Pyrrolidines
• Receptors, Neurokinin-2
• Methacholine Chloride
• Substance P
• Neurokinin A

Topics

• Amino Acid Sequence
• Animals
• Asthma (drug therapy)
• Bronchoconstriction (drug effects)
• Capillary Permeability (drug effects)
• Guinea Pigs
• Humans
• Inositol Phosphates (metabolism)
• Male
• Methacholine Chloride (pharmacology)
• Mice
• Molecular Sequence Data
• Neurokinin A (antagonists & inhibitors)
• Neurokinin-1 Receptor Antagonists
• Piperidines (pharmacology)
• Pyrrolidines (pharmacology)
• Rats
• Receptors, Neurokinin-2 (antagonists & inhibitors)
• Respiration (drug effects)
• Species Specificity
• Substance P (antagonists & inhibitors)