Naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone: a potent, orally bioavailable human CB1/CB2 dual agonist with antihyperalgesic properties and restricted central nervous system penetration.

Selective activation of peripheral cannabinoid CB1 receptors has the potential to become a valuable therapy for chronic pain conditions as long as central nervous system effects are attenuated. A new class of cannabinoid ligands was rationally designed from known aminoalkylindole agonists and showed good binding and functional activities at human CB1 and CB2 receptors. This has led to the discovery of a novel CB1/CB2 dual agonist, naphthalen-1-yl-(4-pentyloxynaphthalen-1-yl)methanone (13), which displays good oral bioavailability, potent antihyperalgesic activity in animal models, and limited brain penetration.

Analysis of human Nav1.8 expressed in SH-SY5Y neuroblastoma cells.

The tetrodotoxin-resistant voltage-gated sodium channel alpha-subunit Nav1.8 is expressed in nociceptors and has been implicated in chronic pain. Difficulties of heterologous expression have so far precluded analysis of the pharmacological properties of human Nav1.8. To address this we have introduced human Nav1.8 in neuroblastoma SH-SY5Y cells. Voltage-clamp analysis showed that human Nav1.8 generated an inward tetrodotoxin-resistant sodium current with an activating threshold around -50 mV, half maximal activation at -11+/-3 mV and a reversal potential of 67+/-4 mV. These properties closely match those of the endogenous rat tetrodotoxin-resistant sodium current in dorsal root ganglia suggesting that the expressed human channel is in a near physiological conformation. Human Nav1.8 was resistant to tetrodotoxin and activated by the pyrethroid toxin deltamethrin. Both voltage-activated and deltamethrin-activated human Nav1.8 were inhibited by the sodium channel blockers BIII 890 CL, NW-1029, and mexiletine. Inhibition of Nav1.8 by these compounds may underlie their known analgesic effects in animal models.

Strategies to identify ion channel modulators: current and novel approaches to target neuropathic pain.

Modulation of ion channel function has been a successful area for drug development, with ion channel modulating drugs being used in the therapeutic treatment of epilepsy, hypertension, diabetes and chronic pain. Most of the ion channel-modulating drugs that are currently on the market were developed without extensive knowledge of the molecular structure of ion channels, or an understanding of the full complexity of ion channel subtypes or knowledge of how ion channel expression is regulated during pathology. As new information on the roles that different ion channel subtypes play in pathophysiological processes becomes available, drugs will be designed to target specific ion channel subtypes via mechanisms that involve either direct channel block or modulation of ion channel functional expression. Using neuropathic pain as an example, this article reviews current knowledge of the structure and function of ion channels and current technology and future opportunities for the identification of novel drugs that are capable of modulating ion channel function.

In vivo pharmacology of SDZ 249-665, a novel, non-pungent capsaicin analogue.

Capsaicin and analogues are valuable analgesic agents when administered to mammals, including humans. However, their pungency and the effects on the cardiovascular and respiratory systems through their general activation of small calibre (nociceptive) primary afferents severely limit their use. Recently, structure activity analysis revealed that the initial pungent and general excitatory effects can be prevented by structural modifications in such a way that the analgesic activity is retained. In this paper we present SDZ 249-665, a capsaicin analogue which produced analgesia in the mouse and anti-hyperalgesic effects in the rat and guinea pig. SDZ 249-665 was administered p.o., s.c. and i.v. in models of nociceptive pain, such as tail flick latency in response to a noxious thermal stimulus and acetic acid-induced writhing in mice, and in models of inflammatory mechanical hyperalgesia induced by turpentine or carrageenan in the rat and guinea pig, respectively. SDZ 249-665 was effective in the tail flick and the writhing assays and produced significant anti-hyperalgesic effects in the inflammatory models. The efficacy of SDZ 245-665 was similar to that of capsaicin, however, it was significantly more potent. SDZ 249-665 did not produce any irritancy in a nose wipe assay in guinea pigs or an eye irritancy assay in rats, while capsaicin was clearly irritant in both cases. Furthermore, unlike capsaicin, SDZ 249-665 did not produce unwanted side effects such as bronchoconstriction and blood pressure changes in the analgesic/anti-hyperalgesic dose range. Thus, a clear analgesic therapeutic window exists for SDZ 249-665. In summary, SDZ 249-665 is a potent orally active, analgesic/anti-hyperalgesic agent in mouse, rat and guinea pig. It lacks the excitatory effects associated with capsaicin and other close analogues, and therefore provides a clear therapeutic window for use in painful conditions. In addition to this favourable profile, no sign of tolerance was detected after a 5 day repeated dose treatment.

The therapeutic and diagnostic potential of FKBPL; a novel anticancer protein.

The immunophilin family of proteins has a vast number of roles regulating a variety of biological processes through protein-protein interactions. A relatively new and divergent member of this family, FK506-binding protein like (FKBPL), is emerging as a key player in the DNA damage response, steroid receptor signalling and more recently, control of tumour growth where it regulates response to endocrine therapy in addition to acting as a novel antiangiogenic protein. As a new therapeutic peptide based on FKBPL approaches clinical trials, this article highlights a unique approach to targeting tumours that are resistant to current antiangiogenic therapies and supports the role of FKBPL as a novel prognostic and predictive biomarker, distinct from its other family members.

Synthesis and SAR of novel 2-arylthiazolidinones as selective analgesic N-type calcium channel blockers.

A series of new N-type (Ca(v)2.2) calcium channel blockers derived from the 'hit' structures 2-(3-bromo-4-fluorophenyl)-3-(2-pyridin-2-ylethyl)thiazolidin-4-one 9 and its 2-[4-(4-bromophenyl)pyridin-3-yl]-3-isobutyl analogue 10 is described. Extensive SAR studies using a range of synthetic approaches resulted in novel, patented compounds with IC50 values of up to 0.2 microM in an in vitro IMR32 assay, and selectivities for N/L of up to 30-fold. The new compounds described have potential in treatment of neuropathic pain.