Safety and pharmacodynamics of venetoclax (ABT-199) in a randomized single and multiple ascending dose study in women with systemic lupus erythematosus.

Objective The anti-apoptotic protein B-cell lymphoma 2 (Bcl-2) may contribute to the pathogenesis of systemic lupus erythematosus. The safety, tolerability, and pharmacodynamics of the selective Bcl-2 inhibitor venetoclax (ABT-199) were assessed in women with systemic lupus erythematosus. Methods A phase 1, double-blind, randomized, placebo controlled study evaluated single ascending doses (10, 30, 90, 180, 300, and 500 mg) and multiple ascending doses (2 cycles; 30, 60, 120, 240, 400, and 600 mg for 1 week, and then 3 weeks off per cycle) of orally administered venetoclax. Eligible participants were aged 18-65 years with a diagnosis of systemic lupus erythematosus for 6 months or more receiving stable therapy for systemic lupus erythematosus (which could have included corticosteroids and/or stable antimalarials). Results All patients (48/48) completed the single ascending dose, 25 continued into the multiple ascending dose, and 44/50 completed the multiple ascending dose; two of the withdrawals (venetoclax 60 mg and 600 mg cohorts) were due to adverse events. Adverse event incidences were slightly higher in the venetoclax groups compared with the placebo groups, with no dose dependence. There were no serious adverse events with venetoclax. The most common adverse events were headache, nausea, and fatigue. Venetoclax 600 mg multiple ascending dose treatment depleted total lymphocytes and B cells by approximately 50% and 80%, respectively. Naive, switched memory, and memory B-cell subsets enriched in autoreactive B cells exhibited dose-dependent reduction of up to approximately 80%. There were no consistent or marked changes in neutrophils, natural killer cells, hemoglobin, or platelets. Conclusions Venetoclax was generally well tolerated in women with systemic lupus erythematosus and reduced total lymphocytes and disease-relevant subsets of antigen-experienced B cells. Registration ClinicalTrials.gov: NCT01686555.

Improvement of bioavailability of the HIV protease inhibitor SC-52151 in the beagle dog by coadministration of the CYP3A4 inhibitor, ketoconazole.

1. SC-52151, an HIV protease inhibitor, is mainly metabolized by CYP3A4 and is poorly bioavailable after oral administration. After i.v. administration of SC-52151 to the female beagle dog (2.5 mg/kg), SC-52151 was rapidly eliminated in plasma with an elimination half-life of about 1 h, a plasma clearance of 44 ml/min/kg and an apparent steady-state volume distribution of 2.2 litre/kg. The high value of plasma clearance of SC-52151 suggests an extensive hepatic first-pass metabolism since SC-52151 is highly protein bound and does not partition itself into red blood cells. 2. The extensive hepatic first-pass metabolism was reduced by coadministration of a CYP3A4 inhibitor, ketoconazole. 3. Dogs were dosed daily with ketoconazole at dose of 100 mg ketoconazole per dog (approximately 10 mg/kg) for 5 days prior to the initiation of coadministration of SC-52151 for 15 days. The doses used for SC-52151 was 0, 60 and 120 mg SC-52151/kg/day (divided t.i.d., 8-h dosing interval). Coadministration of ketoconazole improved the bioavailability of SC-52151 from 4.1 to 9.6% and also improved the Cmax of SC-52151 from 0.41 to 0.83 microgram/ml. 4. Although the absolute bioavailability of SC-52151 was still low (approximately 10%), the Cmax and AUC achieved in this study were satisfactory for conducting chronic toxicology studies. No toxicity associated with the coadministration of ketoconazole was evident. Results from this study suggest that coadministration of ketoconazole might be a practical approach to increase the exposure of SC-52151 in both preclinical and clinical studies.

Dermal inflammation in primates, mice, and guinea pigs: attenuation by second-generation leukotriene B4 receptor antagonist, SC-53228.

Granulocyte infiltration is a prominent feature of human psoriasis. Psoriatic lesional skin contains abnormally high amounts of immunoreactive leukotriene B4 (LTB4), a potent granulocyte chemotaxin in vivo and in vitro. SC-53228 [(+)-(S)-7-(3-}2-(cyclopropylmethyl)-3-methoxy-4- [(methylamino)carbonyl]phenoxy}propoxy}-3,4-dihydro-8-propyl-2H-1- benzopyran-2-propanoic acid], a second-generation LTB4 receptor antagonist, was tested topically and orally in phorbol ester-induced dermal inflammation in three species. Skin inflammation was induced by topical application of phorbol-12-myristate-13-acetate-(PMA/TPA) and assessed by ear thickness, levels of the neutrophil marker enzyme myeloperoxidase (MPO) and histological examination. In mice, SC-53228 inhibited inflammation with a topical ED50 value of 200 +/- 18 micrograms. When applied to guinea pigs, SC-53228 (100 micrograms) inhibited the MPO increase by 86%, while 1000 micrograms abrogated inflammation in rhesus macaques with no plasma accumulation of the drug. A 1% gel formulation was also efficacious in guinea pig PMA-induced epidermal inflammation. Furthermore, single oral dose administration to mice was efficacious (ED50 < 2.5 mg/kg) as was multidose administration to rhesus macaques. PMA-induced skin inflammation possesses some of the attributes of human psoriasis and an agent such as SC-53228 may have utility in the medical management of this condition.

Determination of protein binding by in vitro charcoal adsorption.

Certain compounds such as SC-52151 have extensive nonspecific adsorption to the ultrafiltration devices or to dialysis membranes and therefore can not be measured by the conventional ultrafiltration or equilibrium dialysis methods. A new method based on charcoal adsorption was developed to overcome this difficulty. Unlike many conventional methods, which are based on the separation of free drug from bound drug under equilibrium conditions, the new method is operated under nonequilibrium conditions and involves measuring the time course of decline of the percentage of bound drug remaining in plasma while the free drug is being removed by charcoal adsorption. Theoretical aspects of the method and the data processing procedure are presented. SC-98A, a compound with minimal nonspecific adsorption to the ultrafiltration membrane, was used to demonstrate the applicability of this method against the ultrafiltration method. Using this method, the protein binding of SC-52151 in human plasma at 1.0 microgram/ml was determined to be in the range of 91.4-97.7% at room temperature.

Polymer delivery of the active isomer of misoprostol: a solution to the intestinal side effect problem.

SC-53450 is a new polybutadiene-based polymer system with an acid labile diisopropyl silyl ether linker to which the active isomer of misoprostol (SC-30249) is attached covalently at position C-11. It was studied in rats and dogs to define its profile of gastrointestinal effects relative to misoprostol-hydroxypropyl methylcellulose (HPMC) and the systemic availability of prostaglandin from the polymer. Results of rat studies indicate that SC-53450 has a spectrum of mucosal protective activity similar to misoprostol-HPMC, being protective against indomethacin-induced gastric, cysteamine/indomethacin-induced duodenal and indomethacin-induced lower small bowel damage. SC-53450, in contrast to misoprostol-HPMC, was not diarrheagenic in the rat when administered intragastrically. The observation that SC-53450 is more than 4 times more potent than misoprostol-HPMC suggests the possibility of sustained gastric availability of the prostaglandin SC-30249. SC-53450 exhibited gastric antisecretory activity in histamine-stimulated gastric fistula dogs and protected against acidified aspirin-induced gastric damage in normal fasted beagles. Rat and dog experiments indicate that little, if any, polymer-derived prostaglandin is available systemically, suggesting SC-53450 will have reduced abuse potential in abortion induction. SC-53450 is a potential candidate to replace the present misoprostol formulation in the marketplace for the prevention of nonsteroidal anti-inflammatory drug-induced gastric damage.

Pharmacokinetics of a novel antiarrhythmic drug, actisomide.

The pharmacokinetics of a novel antiarrhythmic drug, actisomide, were examined in the rat, dog, monkey, and human. The terminal half-life of actisomide was similar (1.15-1.89 hr) across species, regardless of dose. The total plasma clearance was higher in the monkey (13.5-16.4 mL/min/kg) than in the dog (9.01-9.32 mL/min/kg), rat (8.6-9.8 mL/min/kg), or human (6.79 +/- 1.07 mL/min/kg). Excretion of the parent drug was higher in urine than in feces in the dog and rat, whereas in the monkey and human, urinary and fecal excretions of actisomide were similar. In humans, atypical plasma concentration-time curves with double peak concentrations were observed following oral doses. Systemic availability of actisomide was higher in the dog than in the rat, monkey, and human. Further, the systemic availability appeared to increase with dose in the rat and monkey. The species-dependent systemic availability appeared to be due primarily to species-dependent absorption of actisomide, and not to species-dependent first-pass metabolism, biliary excretion, and/or renal elimination. The absorption of actisomide in the rat and its in vitro uptake in CaCo-2 cells were pH dependent. The higher systemic availability of actisomide observed in the dog may be due partly to the higher pH in the gastrointestinal (GI) tract of the dog. However, the pH differences in the GI tract of the different species alone did not appear to be enough to explain the difference in systemic availability of actisomide.

Transdermal drug delivery systems of albuterol: in vitro and in vivo studies.

In vitro and in vivo experiments were conducted with double- and single-layer albuterol transdermal pads designed for once-a-day application. In the in vitro experiments, dissolution of albuterol from pads and permeation of albuterol through hairless mouse skin were monitored. In the in vivo experiments, pads were applied to the chest area of four female rhesus monkeys (Macaca mulata), and an albuterol aqueous solution was injected into the saphenous vein of the same animals in a crossover design. The amount lost from pads applied to monkeys was monitored by analysis of pad residue. Blood samples were withdrawn at regular intervals and analyzed by a high-performance liquid chromatography-fluorescence method. Skin irritation due to the pad was measured by a modified Draize score test. The amounts released from the two formulations were similar. The amount released was, however, dependent on the technique used and decreased in the following manner: pad dissolution greater than in vivo amount lost from pads applied to monkeys greater than in vitro permeation through hairless mouse skin. The pharmacokinetic parameters determined after intravenous and transdermal administration were as follows: terminal half-life, 2.26 +/- 0.45 h; apparent volume of distribution, 1935 +/- 37.2 mL.kg-1; and total body clearance, 612.0 +/- 118 mL.h-1.kg-1. The average concentrations in serum after application of single- and double-layer pads were 44.60 +/- 16.40 and 62.50 +/- 8.00 ng/mL, respectively. Further, the amount lost from pads applied to monkeys correlated with the respective amount absorbed in monkeys, as calculated from the average concentration in serum and clearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Rate-limiting steps in oral absorption of a leucotriene D4 antagonist in the beagle dog.

Oral administration of a leucotriene D4 antagonist drug (1) in the Beagle dog at doses of 2, 20, 100, 300, and 800 mg/kg resulted in dose-dependent bioavailability values (4-50%). To understand the dose dependence of the absorption of 1 in the dog, initial rates of absorption of 1, which were estimated from Loo-Riegelman analysis of the concentration in blood data, were analyzed in terms of dissolution and absorption rates. From the Loo-Riegelman plots, the initial rates of absorption of 1 were estimated as 8.2, 41.9, 41.1, 76.1, and 72.8 micrograms.mL-1.h-1, respectively, for the doses given earlier. These data, which indicate leveling of the initial absorption rates at high doses, were consistent with an absorption model in which the dissolution rate is the rate-controlling step in the intestinal absorption of 1 at doses less than 100 mg/kg. The powder dissolution rate of 1 in 17 mM bile salt solution was estimated as 14 and 700 micrograms.mL-1.h-1 for amounts of 1 equivalent to the amounts given to dogs at 2- and 100-mg/kg doses, respectively. After consideration of the volume of distribution and the volume of intestinal fluid in the dog, the value of the initial dissolution rate was much lower than the initial absorption rates at the 2-mg/kg dose. Oral administration of 1 at 2 mg/kg in a 3% polysorbate 80 solution enhanced both the rate and the extent of absorption of the compound. These results confirm the validity of the conclusion that the intestinal absorption of 1 is limited by dissolution rate at low doses.

Expression of gastric antisecretory and prostaglandin E receptor binding activity of misoprostol by misoprostol free acid.

In enriched canine parietal cell preparations, misoprostol, an analog of prostaglandin E1 methyl ester, was rapidly deesterified to misoprostol free acid. Under this circumstance, misoprostol and misoprostol free acid exhibited equal antisecretory potency against histamine-stimulated acid secretion and bound equally well to prostaglandin E receptors. When the deesterification of misoprostol was inhibited by paraoxon, an esterase inhibitor, the antisecretory and receptor binding activity of misoprostol was markedly reduced, with potency much less than misoprostol free acid. These results indicate that misoprostol free acid is the active biological form of misoprostol that binds to prostaglandin E receptors and mediates the antisecretory action of misoprostol.

BCNU-induced quantitative and qualitative changes in hepatic cytochrome P-450 can be correlated with cholestasis.

Male Sprague-Dawley rats were given single i.p. injections of 1,3-bis(2-chloroethyl)-1-Nitrosourea (BCNU) to investigate changes in hepatic microsomal cytochrome P-450 content and metabolic activity. On day 14 after treatment (20 mg/kg), cytochrome P-450 content had decreased by approximately 25% and ethylmorphine N-demethylase activity (nmol product/nmol P-450/min) had decreased by 36%. In contrast, ethylmorphine O-deethylase and 7-ethoxycoumarin O-deethylase activities were not significantly decreased by BCNU treatment. Hepatic delta-aminolevulinic acid synthetase activity was only 60% of control values, and microsomal heme oxygenase activity was slightly but not statistically elevated. Cytochrome P-450 content in control and BCNU-treated rats increased in a similar manner after phenobarbital or beta-naphthoflavone induction. Electrophoretic analysis of cytochrome P-450 proteins isolated from hepatic endoplasmic reticular membranes of treated and control rats suggested that alterations in these proteins occurred in BCNU-treated rats. These changes in cytochrome P-450 content and activity are very similar to those reported in isolated systems exposed to bile acids or in rats with experimentally produced cholestasis. BCNU has been shown to produce cholestasis, which precedes its effects on microsomal mixed-function oxygenase activity. Thus, the delayed effects of BCNU on microsomal drug metabolism are probably secondary to its interference with bile formation.

Simultaneous quantification of ethylmorphine O-deethylase and N-demethylase activity by high-performance liquid chromatography.

The N-demethylation and O-deethylation of ethylmorphine by cytochrome P-450 are simultaneously measured using high-performance liquid chromatography. All the metabolites and the substrate are extracted from the enzymatic incubation mixture with isopropanol-methylene chloride (20:80) containing 6.0 micrograms/ml codeine sulfate as an internal standard. Separation of the compounds is achieved on a C18 reversed-phase column using a mobile phase of 1% acetic acid--acetonitrile (85:15) with 1-hexanesulfonic acid as a counter-ion. Total run time is 12 min at a flow-rate of 2.0 ml/min and 144 bar. Assay of ethylmorphine N-demethylase and O-deethylase activities in rat liver microsomes revealed close agreement between this method and conventional ones. N-Demethylation was found to greatly exceed O-deethylation in liver microsomes from either control or phenobarbital-treated rats confirming results from other laboratories. This method can also be used to measure the N- and O-demethylation of codeine.