Pharmacological characteristics of Ro 115-1240, a selective alpha1A/1L-adrenoceptor partial agonist: a potential therapy for stress urinary incontinence.

OBJECTIVE: To describe the preclinical pharmacology of Ro 115-1240, a peripherally acting selective alpha1A/1L-adrenoceptor (AR) partial agonist, compared with the alpha1A/1L-AR full agonist amidephrine, as AR agonists have some utility in the treatment of stress urinary incontinence (SUI) but are limited by undesirable cardiovascular and central nervous system side-effects. RESULTS: In radioligand-binding studies Ro 115-1240 had greater affinity for alpha1A than for alpha1B and alpha1D subtypes. The potency and intrinsic activity of amidephrine and Ro 115-1240 relative to noradrenaline were determined in native and cell-based assays using human recombinant alpha1-ARs; they acted as selective alpha1A/1L-AR full and partial agonists, respectively. In anaesthetized micropigs and rabbits, amidephrine and Ro 115-1240 produced non-selective, dose-dependent increases in intraurethral and arterial blood pressures but the magnitude of the pressure increases evoked by Ro 115-1240 were about a third of those with amidephrine. In conscious micropigs both agents produced dose-dependent increases in urethral tension. Again, the magnitude of the urethral response to Ro 115-1240 was about a third of that with amidephrine. More importantly, only amidephrine produced dose-dependent increases in blood pressure and decreases in heart rate. Ro 115-1240 produced a maximum increase in urethral tension with no effect on blood pressure or heart rate. CONCLUSION: These results show that by combining selectivity for the alpha1A/1L-AR subtype with a reduction in intrinsic agonist efficacy, Ro 115-1240 has reduced haemodynamic effects while retaining to some degree the contractile effects on urethral smooth muscle. These studies indicate that Ro 115-1240 may be useful as a novel treatment for SUI.

Characterization of the analgesic and anti-inflammatory activities of ketorolac and its enantiomers in the rat.

The marked analgesic efficacy of ketorolac in humans, relative to other nonsteroidal anti-inflammatory drugs (NSAIDs), has lead to speculation as to whether additional non-NSAID mechanism(s) contribute to its analgesic actions. To evaluate this possibility, we characterized (R,S)-ketorolac's pharmacological properties in vivo and in vitro using the nonselective cyclooxygenase (COX) inhibitors [indomethacin (INDO) and diclofenac sodium (DS)] as well as the selective COX-2 inhibitor, celecoxib, as references. The potency of racemic (R,S)-ketorolac was similar in tests of acetic acid-induced writhing, carrageenan-induced paw hyperalgesia, and carrageenan-induced edema formation in rats; ID50 values = 0.24, 0. 29, and 0.08 mg/kg, respectively. (R,S)-ketorolac's actions were stereospecific, with (S)-ketorolac possessing the biological activity of the racemate in the above tests. The analgesic potencies for (R,S)-, (S)-, and (R)-ketorolac, INDO, and DS were highly correlated with their anti-inflammatory potencies, suggesting a common mechanism. (R,S)-ketorolac was significantly more potent than INDO or DS in vivo. Neither difference in relative potency of COX inhibition for (R,S)-ketorolac over INDO and DS nor activity of (S)-ketorolac at a number of other enzymes, channels, or receptors could account for the differences in observed potency. The distribution coefficient for (R,S)-ketorolac was approximately 30-fold less than for DS or INDO, indicating that (R,S)-ketorolac is much less lipophilic than these NSAIDs. Therefore, the physicochemical and pharmacokinetics properties of (R,S)-ketorolac may optimize the concentrations of (S)-ketorolac at its biological target(s), resulting in greater efficacy and potency in vivo.

Stability of prostacyclin analogues: an unusual lack of reactivity in acid-catalyzed alkene hydration.

Prostacyclin analogue 5 undergoes specific acid-catalyzed hydration (kH+ = 1.9 x 10(-7)M-1 sec-1 at 25 degrees C) and a pH-independent oxidation reaction (k0 = 1.2 x 10(-10) sec-1 at 25 degrees C) above pH approximately 5. The hydration reaction for 5 is much slower than for other structurally similar exocyclic alkenes, even though the rate-determining step is proton transfer. This slowness of reaction and an analysis of the pH-rate profile show that 5 does not exhibit significant intramolecular general acid catalysis, as does prostacyclin.

Platelet aggregation inhibitory activity and vasodepressor activity of a series of bicyclo[3.2.0]hept-6-ylidene iminoxy alkanoic acids with modified lower side chains.

Prostacyclin analogues derived from modification of the lower side chain of the bicyclo[3.2.0]hept-6-ylidene iminoxyacetic acid (1) were studied in inhibition of in vitro and ex vivo platelet aggregation and in the spontaneously hypertensive rat. Iminoxyacetic acids (13a), (13b), (13c) and iminoxypropionic acid (14b) were 2.9, 3.0, 1.9 and 2.0 times respectively more potent than PGE1 in inhibiting ADP-induced aggregation of human platelets in vitro. Following intravenous administration at a dose of 90-110 micrograms/kg in the guinea pig, iminoxyacetic acids (13a), (13c) and iminoxypropionic acid (14b) showed a maximum inhibition of 82-92% with a half life in the range of 14-22 min. Following oral administration at a dose of 1 mg/kg in the guinea pig, iminoxyacetic acids (13a) and (13b) inhibited heterologous platelet aggregation for 4.5 h. Following intravenous administration in spontaneously hypertensive rats, acids (13a)-(13c) and (14b) lowered the mean blood pressure in a dose dependent manner. At a dose of 100 micrograms/kg, the effect lasted for 20-40 min.

Orally active prostacyclin-mimetic RS-93427: therapeutic potential in vascular occlusive disease associated with atherosclerosis.

RS-93427 is a potent, orally active prostacyclin-mimetic that is very rapidly absorbed but with generally long-lived actions in most species. It has antithrombotic, thrombolytic, and antivasospastic potential. Alone among several tested PGI-mimetics, it inhibits release of platelet mitogens more potently than its ability to inhibit aggregation. It also inhibits mitogen release from macrophages and vascular endothelial cells. RS-93427 is also potent at inhibiting macrophage accumulation of cholesteryl esters. These data suggest a broad spectrum of potential therapeutic utility for RS-93427 via the oral route. It might be useful both in acute manifestations of vascular occlusive disease involving thrombosis and vasospasm, in addition to the more chronic conditions involving intimal hyperplasia (as in arteriovenous grafts) and possibly frank atherosclerosis. Much work remains to be done, including examination of RS-93427 in chronic studies with various dosage forms, particularly in the study of atherosclerosis.

Synthesis and platelet aggregation inhibition activity of a series of enantiomeric bicyclo[3.2.0]heptane-6-oximinoacetic acids (1).

Opening of racemic epoxide (3) with (3S)- or (3R)-dimethyl-3-(dimethyl-t-butylsilyloxy)oct-1-ynyl aluminum gave two regioisomers, which were separated chromatographically. The separated regioisomers, themselves mixtures of chromatographically inseparable diastereoisomers, were converted into their dicobalthexacarbonyl complexes, which were easily resolved and isolated by chromatography. The individual diastereoisomers were deprotected to give bicyclo[3.2.0]heptan-3-ones, whose absolute stereochemistry was assigned using circular dichroism. One of these compounds, (1R,2R,3S,5R,3'S)-3-(3'-hydroxyoct-1'-ynyl)-bicyclo[3.2.0]++ +heptan-2-ol-6- oximinoacetic acid (11a) was 4.5 times more potent than PGE1 in inhibiting the ADP-induced aggregation of human platelets. The next most potent compound in this series was the "ent-15-epi" compound (11b), which was 0.034 times the potency of PGE1 in the platelet aggregation assay.