A-841720, a novel, potent and non-competitive mGluR1 antagonist in models of pain and of motor and cognitive function, is being under development by Merz Pharmaceuticals GmbH. It is a selective non-competitive mGlu1 receptor antagonist (IC50: 10 nM); showing 34-fold selectivity over mGluR5 and no significant activity at other mGluR receptors, neurotransmitter receptors, ion channels, and transporters. A-841720 demonstrated full efficacy in various in vivo animal pain models.

A-803467 is a selective NaV1.8 channel blocker with IC50 of 8 nM, blocks tetrodotoxin-resistant currents, exhibits >100-fold selectivity against human NaV1.2, NaV1.3, NaV1.5, and NaV1.7. A-803467 reduces behavioral measures of chronic pain. Systemic administration of A-803467 demonstrated acute antinociceptive activity as measured as a reduction in mechanical allodynia in several models of inflammatory and neuropathic pain in rats. Additionally, systemic and intraspinal delivery of A-803467 attenuates both evoked and spontaneous firing of wide dynamic range neurons in rats with spinal nerve ligations.

A bone resorption inhibitor, A-75943, isolated from the fermentation broth of Streptomyces sp. SANK 61296, was found to be structurally related to cycloheximide, from which A-75943 was prepared chemically. A-75943 inhibited in vitro bone resorption in a concentration-dependent manner, with maximal nontoxic inhibition greater than 90% at 5ug/ml and an IC50 of 0.35uM.