Pharmacokinetics and biochemical efficacy of pirmagrel, a thromboxane synthase inhibitor, in renal allograft recipients.

The effects of a 48-hour 0.5 mg/kg/hr infusion of the thromboxane synthase inhibitor pirmagrel were studied in 10 renal allograft recipients with cyclosporine nephrotoxicity. Plasma concentrations reached a mean steady-state plasma level of 1798 +/- 481 ng/ml. Biphasic, rapid elimination of pirmagrel was observed with a distribution half-life of 6.7 minutes and a terminal half-life of 73 minutes. Plasma clearance and the volume of distribution of the drug were 300 +/- 87 ml/hr/kg and 497 +/- 232 ml/kg, respectively. The pharmacodynamic effects of pirmagrel were marked by a mean 96% suppression of serum thromboxane B2 (TXB2), which coincided with a suppression of urinary excretion of TXB2, 2,3-dinor-TXB2, and 11-dehydro-TXB2 of 85% +/- 8%, 91% +/- 5%, and 89% +/- 9%, respectively. Urinary excretion of all thromboxane metabolites measured at the end of 1 week after termination of infusion was returned to the baseline. In conclusion, pirmagrel caused effective and sustained suppression of all thromboxane derived metabolites in plasma and urine during continuous infusion in kidney transplant patients receiving cyclosporine.

Benzofuro[2,3-c]pyridin-6-ols: synthesis, affinity for opioid-receptor subtypes, and antinociceptive activity.

A general synthetic approach to a novel series of cis-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridin-6-ols is described together with their receptor-binding profile on opioid-receptor subtypes (mu, kappa, delta). In addition, their in vivo antinociceptive activity was assessed. A number of the analogues synthesized showed potent affinity for opioid receptors and have potent antinociceptive activity in a mouse phenylquinone abdominal stretching model. In addition, the SAR for nitrogen substitution in the above series is explored with respect to the overall opioid receptor subtype binding profile. In general it was found that substituents which enhanced mu and kappa binding affinity in the benzomorphan series had a similar effect in the benzofuropyridine series described in this manuscript. An overlap hypothesis topologically connecting the benzomorphan nucleus to the cis-1,2,3,4,4a,9a-hexahydrobenzofuro[2,3-c]pyridine nucleus is also presented.

Synthesis, opioid receptor binding profile, and antinociceptive activity of 1-azaspiro[4.5]decan-10-yl amides.

A series of azaspiro[4.5]decanyl amides were prepared by a novel cyclization route and examined for opiate receptor binding and antinociceptive activity. Selected tertiary amides in this series showed potent selective mu-receptor binding and antinociceptive activity, in contrast to the less conformationally restricted secondary amides, which showed relatively weak activity. Although structurally similar to the kappa-agonist U-50488H (1), these compounds showed virtually no tendency to bind to the kappa-receptor. An X-ray crystal structure of compound (21) confirms that the spirocyclic amine does not cause distortion away from the chair conformation of the cyclohexane ring. Either this receptor has very specific requirements for the orientation of the two nitrogens of these compounds or this ring system fills a portion of space more readily tolerated by the mu- and delta-receptors.

Evidence for a cholinergic fiber tract connecting the thalamus with the head of the striatum of the rat.

Placement of electrolytic lesions in the zona incerta or parafascicular nucleus of the rat forebrain resulted in a marked reduction of choline acetyltransferase (ChAc) activity in the head of the striatum 2-4 weeks later. Lesions of the habenula did not cause this effect implying that concomitant destruction of the fasciculus retroflexus with the parafascicular nucleus was not responsible for the effects observed. The data suggest that there is a cholinergic fiber tract connection between the parafascicular nucleus of the thalamus and the head of the striatum in the rat forebrain.

CGS 8216 and CGS 9896, novel pyrazoloquinoline benzodiazepine ligands with benzodiazepine agonist and antagonist properties.

CGS 8216 and CGS 9896 are two recently described compounds which interact with benzodiazepine binding sites but have pharmacological, biochemical and behavioral characteristics which distinguish them from classical benzodiazepines. CGS 8216 shows properties of a weak inverse agonist, while CGS 9896 shows properties of a mixed agonist/antagonist. Experiments using quantitative autoradiography to determine benzodiazepine binding site interactions of these compounds in discrete anatomical areas are described. Results indicate that [3H]-CGS 8216 does not show any regional differentiation in binding characteristics in 7 brain areas studied. CGS 9896 preferentially inhibited [3H]-flunitrazepam from cerebellar sites compared to hippocampal dentate gyrus sites, but the magnitude of this effect was small. These data support the conclusion that CGS 9896 is acting preferentially at putative benzodiazepine type 1 sites and is consistent with the mixed agonist/antagonist profile of the compound.

Increased intra-articular substance P and prostaglandin E2 following injection of interleukin-1 in rabbits.

Inflammation was induced by intra-articular injection of 100 ng recombinant human interleukin-1 alpha (rhIL-1) into rabbit knees. Substance P (SP) and prostaglandin E2 (PGE2) were measured by radioimmunoassay (RIA) in the joint fluid at 4, 24 and 48 h after rhIL-1 injection. SP was increased by 4 h, further increased at 24 h and remained elevated at 48 h. PGE2 concentration was highest at 4 h and remained elevated at 48 h after rhIL-1 injection. Because of the proinflammatory activities of SP and PGE2, our studies suggest that the elevated SP and PGE2, in the joint may amplify or sustain an initial receptor-mediated inflammatory response to IL-1.

Effects of haloperidol and d-amphetamine on in vivo 3H-spiroperiodol binding in the rat forebrain(1).

Specific (3)H-spiroperidol ((3)H-Sp) binding was demonstrated to occur, in vivo, throughout the rat forebrain. The highest concentrations of (3)H-Sp were found in regions known to contain dopamine neuron terminals. Acute and repeated administration of low does of haloperidol decreased in vivo (3)H-Sp in subcortical but not cortical regions. Repeated administration of high does of haloperidol followed by washout periods up to 8 days did not lead to an increase in in vivo (3)H-Sp binding; however, a single dose of d-amphetamine caused substantial increases. Analysis of the alterations induced by haloperidol and d-amphetamine suggest that the dopamine receptor changes configuration upon excessive exposure to agonists or antagonists in such a way as to favor the counterpart ligand.

Effects of indomethacin, triamcinolone, and dexamethasone on recombinant human interleukin-1-induced substance P and prostaglandin E2 levels in rabbit knee joints.

Intra-articular (i.a.) injection of recombinant human interleukin-1 alpha (rHuIL-1 alpha) in rabbit knees induced both an inflammation, as determined by increases in leukocytes in the joint fluid, and cartilage degradation, as measured by loss of proteoglycan. Substance P (SP) and prostaglandin E2 (PGE2) levels in the joint lavage are also elevated. Treatment with 5 mg indomethacin/kg, p.o., b.i.d., 2 mg triamcinolone i.a., and 10 mg dexamethasone/kg, p.o., reduced synovial lavage leukocyte counts, as well as PGE2 and SP lavage concentrations induced with IL-1 injection. However, none of the treatments inhibited rHuIL-1-induced proteoglycan loss.

Fetal and maternal response to intravenous infusion of a thromboxane synthetase inhibitor.

Pharmacologic inhibition of thromboxane synthetase activity has reversed the clinical manifestations of toxemia in the ovine model. To investigate placental transfer and fetal effects of a selective thromboxane synthetase inhibitor, CGS13080 (Ciba-Geigy, Summit, N.J.) was intravenously infused into eight singleton- or twin-bearing ewes near term. During CGS 13080 infusion (0.1 mg/kg/hr), maternal steady-state CGS 13080 levels of 102 +/- 18 ng/ml were achieved within 30 minutes and maternal serum thromboxane generation decreased significantly (13 +/- 3 to 4 +/- 1 ng/ml). However, fetal serum levels of CGS 13080 were only 4% of peak maternal concentrations and fetal serum thromboxane generation did not change. There was no evidence of change in uterine blood flow, maternal or fetal blood pressure, heart rate, blood gas values, or fetal or maternal metabolites of prostacyclin or prostaglandin E2 during the study. We speculate that CGS 13080 may be efficacious in the treatment of human pregnancy-induced hypertension.

The heterologous expression and characterization of human prostaglandin G/H synthase-2 (COX-2).

The open reading frame of human cyclooxygenase-2 was cloned by pcr amplification of IL-1 beta stimulated human dermal fibroblast cDNA. The coding region was used to construct a recombinant baculovirus which when used to infect Sf9 cells directed the expression of recombinant human cyclooxygenase-2. The heterologously expressed enzyme was characterized and found to display all salient features of cyclooxygenase. Large-scale microsomal preparations of infected cells yielded more than 20 units of enzyme with a specific activity of 240 nmoles prostaglandin product/mg protein.