A comparison of the pharmacokinetics and tolerability of the anti-migraine compound almotriptan in healthy adolescents and adults.

This study was designed to assess and compare the pharmacokinetics and tolerability of almotriptan, a 5-HT1B/1D agonist used to treat migraine attacks, in adolescents and adults. Healthy adolescents (n = 18) and adults (n = 18) received a single 12.5-mg dose of almotriptan after fasting overnight. Plasma and urinary almotriptan concentrations were measured by high-performance liquid chromatography. Pharmacokinetic parameters of almotriptan were determined by non-compartment analysis. The 90% confidence interval (CI) approach was employed to assess age effects. Mean Cmax, tmax, area under the curve (AUC0- infinity ), half-life, and percentage excreted in urine were nearly identical for the two populations. Mean oral (CLPO) and renal (CLR) clearances were similar between the age groups; however, weight-corrected CLPO was approximately 32% higher (90% CI 16, 51) in adolescents compared with adults. The higher weight-corrected CLPO appeared to offset increases in exposure expected on the basis of lower body weight in adolescents. The findings were the same when a subgroup (n = 9) of 12-14-year-old children was compared with adults. The type, incidence and severity of adverse events were similar between the two age groups and were consistent with those reported previously during adult clinical trials. Based on these pharmacokinetic and tolerability findings, no dose adjustment for almotriptan would be required when treating patients as young as 12 years old.

Dose-independent pharmacokinetics of the cardioprotective agent dexrazoxane in dogs.

A randomized, four-way cross-over design was used to assess the disposition of the cardioprotective agent, dexrazoxane, in four male beagle dogs following single I.V. administration of 10, 25, 50, and 100 mg kg-1 doses. Parent drug was quantified in plasma and urine with a validated high-pressure liquid chromatographic-electrochemical assay. A two-compartment open model adequately described the dexrazoxane plasma concentration versus time data. The terminal half-life ranged between 1.1 and 1.3 h and the apparent steady-state distribution volume was 0.67 L kg-1. The systemic clearance (CL) ranged from 10.3 to 11.5 mL min-1 kg-1, while estimates of renal clearance approximated the glomerular filtration rate (GFR approximately 3.2-4.9 mL min-1 kg-1). Over the dose range evaluated, CL was dose independent (ANOVA, p = 0.33), while concentration at the end of infusion (Cend) and the area under the concentration versus time curve (AUC) were directly proportional to the dose (r > 0.999). The blood cell to plasma partitioning ratio was approximately 0.517 and drug was essentially unbound to plasma proteins (fu approximately 0.95). Dexrazoxane appeared to be subject to low organ extraction, since the hepatic and renal drug extraction ratios were on the order of 0.228 +/- 0.054 and 0.184 +/- 0.024, respectively. These results suggest a relatively small drug distribution space (approximately equal to total-body water) and low tissue and plasma protein binding. In light of the low plasma protein binding and extraction ratio exhibited by dexrazoxane, metabolic capacity and renal function would appear to be the predominant variables affecting the CL of this drug. The constancy of the half-life, CL, and VSS with increasing dose indicates dose-independent disposition for dexrazoxane. Thus a linear increase in the systemic exposure can be predicted over this dose range.

Influence of the cardioprotective agent dexrazoxane on doxorubicin pharmacokinetics in the dog.

The influence of dexrazoxane on doxorubicin pharmacokinetics was investigated in four dogs using the two treatment sequences of saline/doxorubicin or dexrazoxane/doxorubicin. Intravenous doses of 1.5 mg/kg doxorubicin and 30 mg/kg (the 20-fold multiple) dexrazoxane were given separately, with doxorubicin being injected within 1 min of the dexrazoxane dose. Both doxorubicin and its 13-dihydro metabolite doxorubicinol were quantified in plasma and urine using a validated high-performance liquid chromatographic (HPLC) fluorescence assay. The doxorubicin plasma concentration versus time data were adequately fit by a three-compartment model. The mean half-lives calculated for the fast and slow distributive and terminal elimination phases in the saline/doxorubicin group were 3.0 +/- 0.5 and 32.2 +/- 12.8 min and 30.0 +/- 4.0 h, respectively. The model-predicted plasma concentrations were virtually identical for the saline and dexrazoxane treatment groups. Analysis of variance of the area under the plasma concentration-time curve (AUCo-infinity), terminal elimination rate (lambda z), systemic clearance (CLs), and renal clearance (CLr) for the parent drug showed no statistically significant difference (P greater than 0.05) between the two treatments. Furthermore, the doxorubicinol plasma AUCo-t value and the doxorubicinol-to-doxorubicin AUCo-t ratio showed no significant difference, demonstrating that dexrazoxane had no effect on the metabolic capacity for formation of the 13-dihydro metabolite. The total urinary excretion measured as parent drug plus doxorubicinol and the metabolite-to-parent ratio in urine were also unaffected by the presence of dexrazoxane. The myelosuppressive effects of doxorubicin as determined by WBC monitoring revealed no apparent difference between the two treatments. In conclusion, these results show that drug exposure was similar for the two treatment arms. No kinetic interaction with dexrazoxane suggests that its coadministration is unlikely to modify the safety and/or efficacy of doxorubicin.

A sensitive and specific procedure for quantitation of ADR-529 in biological fluids by high-performance liquid chromatography (HPLC) with column switching and amperometric detection.

An HPLC method using electrochemical detection (ED) has been validated for the determination of ADR-529 in plasma and urine using ICRF-192 as an internal standard (IS). Prior to storage and quantitation, both plasma and urine samples require acid stabilization. Acidified plasma samples were prepared for HPLC using a two column solid-phase extraction (SPE). An aliquot of buffered plasma (i.e., pH 6-7) was first deproteinated and desalted on a C-18 SPE column. The analytes were then eluted onto a C-8 SPE column where retention and selective cleanup were achieved in the cation-exchange mode via silanol interactions. Acidified urine samples were diluted in acetonitrile prior to injection. The HPLC system for plasma and urine samples employed two narrow-bore silica columns used in the weak cation-exchange mode and separated by a switching valve. To prohibit late-eluting peaks from passivating the glassy carbon working electrode, a heart-cut containing ADR-529 and the IS was vented from the first silica column to the second using an automated switching valve. Amperometric detection at an oxidation potential of +1050 mV vs a Ag/AgNO3 reference electrode was used. Linearity was validated between 5 and 500 ng/ml in plasma and between 2 and 100 micrograms/ml in urine. Imprecision and percentage bias were typically less than 10% for both plasma and urine controls throughout their respective dynamic ranges. The absolute recoveries for ADR-529 and the IS from plasma were greater than 95%. This method is being successfully applied to the pharmacokinetic/dynamic evaluation of ADR-529 in animals and humans.

Products of cultured neuroglial cells: II. The production of fibronectin by C6 glioma cells.

The possibility of fibronectin production by C6 glioma cells was examined with assays which require protein synthesis. Proteins produced by C6 cells using radiolabeled amino acid precursors were tested for affinity to collagen by binding to immobilized gelatin. The predominant collagen binding protein made by C6 coelectrophoresed with fibronectin synthesized by control fibroblasts and with the larger of the two proteins in unlabeled fibronectin when applied to polyacrylamide gels with sodium dodecyl sulfate (SDS). In addition, C6 produced a larger collagen binding protein of approximately 270,000 molecular weight. Solubilities in urea solutions of the collagen-binding proteins made by C6 cells and fibroblasts were similar. Immunofluorescence showed fibronectin associated with the C6 cell monolayer, but less abundant than the fibronectin associated with fibroblasts. Results provide evidence for the production of fibronectin by the C6 glioma cell line.

Penetration of trolamine salicylate into the skeletal muscle of the pig.

Studies to determine the extent of local tissue penetration of topically applied trolamine [14C]salicylate were conducted in domestic pigs. The preparation was applied onto a 100-cm2 shaved area of skin overlying the biceps femoris at a concentration of 0.7 mg of salicylate/cm2 to closely approximate the actual use in humans. At least 82% of the topically applied trolamine salicylate was absorbed over a 2-h period. Based on blood and muscle salicylate levels, a localization of the absorbed drug occurred in muscle underlying the treated area within 120 min. Muscle from the treated area had a concentration of salicylate that was 13 times that of blood and 49 times that of muscle taken from untreated areas. Blood samples taken from the treated area at 10, 20, and 30 min showed that salicylate levels ranged from 15.8 to 5.3 micrograms/g. Less than 0.5% of the applied drug was excreted in the urine during the 2-h period.

Antilipidemic activity of 4-oxo-functionalized ethyl 6-chlorochroman-2-carboxylate analogs and a related tricyclic lactone in three rat models.

The synthesis of ethyl cis-6-chloro-4-hydroxychroman-2-carboxylate (IV) and 6-chloro-4-hydroxy-chroman-2-carboxylic acid lactone (V) are reported. The antilipidemic properties of these compounds in 3 rat models were compared to the activity obtained for the previously synthesized related analogs ethyl 6-chlorochroman-2-carboxylate (II), ethyl 6-chlorochromanone-2-carboxylate (III) and clofibrate (I). The biologically most interesting analog, ethyl 6-chlorochroman-2-carboyxlate (II) like clofibrate (I), was an effective antitriglyceridemic and anticholesterolemic agent in Triton WR-1339 hyperlipidemic rats, sucrose-fed hyperlipidemic rats and chow-fed normolipemic rats. Ethyl 6-chlorochromanone-2-carboxylate (III) was found to be active after 7 days of administration to sucrose-fed rats. In sucrose-fed, male Sprague-Dawley rats, the comparative effects of these analogs on various hepatic drug parameters also were carried out. Consistent with previous findings, results obtained with these compounds provide evidence showing that changes in hepatic HMG-CoA reductase activity bear no relationship to serum cholesterol lowering in the sucrose-fed model.

Burns due to grain dust explosions.

Dust explosions occurring in grain elevator storage and processing operations are increasing in frequency and are a world-wide source of injury and fatality. Despite extensive investigation by both private and governmental interests, the causes of most grain dust explosions remain a mystery. A number of methods to help prevent such explosions have been developed, but none has gained uniform acceptance. Despite a brief contact with flame in the flash of a dust cloud ignition, temperatures may exceed 1,000 degrees F and can cause severe burns. A single burn center's experience with eight patients injured in three separate grain elevator dust explosions during a 12-month period highlights the potential seriousness of the problem. Physicians practicing in grain producing or shipping areas of the world should be aware of the potential hazard imposed by grain storage operations. Prevention of these explosions by mandatory dust control systems and appropriate safety regulations is emphasized.

Synthesis and pharmacological evaluation of cis-3,4,4a,9a-tetrahydro-1H-pyrano[3,4-b]benzofuran-1-ones. Tricyclic analogues related to the antilipidemic drug clofibrate.

The chemistry and pharmacology of two delta-lactones, cis-6-chloro-9a-methyl-3,4,4a,9a-tetrahydro-1H-pyrano[3,4-b]benzofuran-1-one (2) and the 9a-demethyl analogue 3, are reported. Lactones were prepared from dihydrobenzofuran precursors possessing geometrical configurations confirmed both by synthesis and 1H NMR spectroscopy. All cis-dihydrobenzofurans exhibited Jvic = 9.0-10.8 Hz, whereas their trans isomers exhibited Jvic = 5.0--6.0 Hz in agreement with predictions based on the Karplus equation. The pharmacological profiles for 2 and 3 were compared to that of clofibrate (1) in normal male Sprague-Dawley rats. Using equimolar doses (0.4 mmol/kg, po, twice daily for 7 days), 1 exhibited both anticholesterolemic and antitriglyceridemic activity, lactone 2 exhibited only antitriglyceridemic activity, and 3 was inactive as an antilipidemic agent. No correlation was observed for inhibition of hepatic HMG-CoA reductase activity and serum cholesterol lowering.

2-Indanpropionic acids: structural leads for prostaglandin F2alpha antagonist development.

A rationale is presented for the development of prostaglandin F2alpha receptor antagonists. The target analogue, 5,6-(dibenzyloxy)-1-oxo-2-propyl-2-indanpropionic acid (3), was shown to have selective activity for antagonism of PGF2alpha when compared to the antagonism of acetylcholine and KCl on the mouse ileum, whereas other 2-indanpropionic acids (1, 2, 4), not substituted with benzyl functions, were considerably less active and nonselective. The results suggest that 3 may serve as a lead compound for further drug development.

Synthesis and pharmacological evaluation of a clofibrate-related tricyclic spirolactone, 5-chloro-4',5-dihydrospiro[benzofuran-2(3H),3'(2'H)-furan]-2'-one.

The chemistry and pharmacology of the title compound, spirolactone 4, are reported. The synthesis represents a new approach to the preparation of spiro compounds. The pharmacological profiles of 4 are compared to that of clofibrate in Triton-induced hyperlipidemic, sucrose-fed, and normal Sprague-Dawley rat models. Clofibrate was effective in all animal models, but the spirolactone 4 exhibited antitriglyceridemic activity only in the Triton model. The inactivity of 4 in sucrose- and chow-fed rats could not be attributed to a resistance to hydrolysis by serum esterases. Comparative studies revealed that inhibition of hepatic HMG-CoA reductase activity may not be an index of hypocholesterolemic action in sucrose-fed rats. Additionally, only clofibrate exhibited significant changes in components of the hepatic microsomal monooxygenase system.

Pharmacology on rat ileum of certain 2-substituted 3-(dimethylamino)-5,6-dimethoxyindenes related to 5,6-(methylenedioxy)indene calcium antagonists.

Whereas the 2-propyl- and 2-butyl-5,6-(methylenedioxy)indene calcium antagonists reversed the spasmogenic action of several agonists including PGF2alpha and acetylcholine at 5 X 10(-5) to 10(-4) M on the rat ileum, the corresponding 5,6-dimethoxy analogues exhibited spasmogenic activity at higher concentration (10(-4)-10(-3) M) and exhibited neither spasmogenic nor spasmolytic activity at lower (10(-6)-10(-5) M) concentration. The results are compared to the methyl and 2-ethyl analogues. At 10(-4) M only the butyl analogue was capable of moderate antagonism of acetylcholine and at 10(-3) M all four analogues were capable of moderately antagonizing the actions of acetylcholine.

Diethyl (4baalpha,4calpha,9aalpha,9balpha)-3,6-dichlorocyclobuta[1,2-b:3,4-b']bisbenzofuran-9a,9b(4bH,4cH)-dicarboxylate: the cis,syn photodimer of ethyl 5-chlorobenzofuran-2-carboxylate, an analogue related to the antilipidemic drug clofibrate.

The antilipidemic properties of diethyl (4balpha,4calpha,9aalpha,4balpha)-3,6-dichlorocyclobutal[1,2-b:3,4-b']bisbenzofuran-9a,9b(4bH,4cH)-dicarboxylate, herein termed dimer 8, were studied in sucrose-fed and in Triton-induced hyperlipidemic rats. Whereas clofibrate (0.4 mmol/kg) exhibited both anticholesterolemic and antitriglyceridemic activity, dimer 8 showed only antitriglyceridemic properties at the lower dose (0.2 mmol/kg) in sucrose-fed rats. Dimer 8 only lowered serum triglycerides levels in Triton WR-1339 hyperlipidemic rats, whereas clofibrate lowered both cholesterol and triglyceride levels. In the chronic sucrose-fed model, dimer 8 and clofibrate lowered hepatic HMG-CoA reducatase activity and produced significant elevations in several parameters of hepatic drug metabolism. No positive relationship between serum cholesterol lowering and reduction of hepatic HMG-CoA reductase activity was observed by these agents in sucrose-fed rats.

Synthesis and antilipidemic properties of cis-7-chloro-3a, 8b-dihydro-3a-methylfuro[3,4-b]benzofuran-3(1H)-one, a tricyclic clofibrate related lactone having a structural resemblance to mevalonolactone.

The synthesis for the title lactone 2, designed to be an antagonist of the enzyme HMG-CoA reductase (E.C.1.1.1.34), is described. Lactone 2, its synthetic tricyclic hemiacetal precursor 4, and clofibrate were investigated for their antilipidemic activity in 7-day treated normal and in Triton WR-1339 induced hyperlipidemic male Sprague-Dawley rats. After 7-day drug administration to normal rats, lactone 2 was less effective than clofibrate in lowering HMG-CoA reductase activity and serum cholesterol; however, unlike clofibrate, lactone 2 did not increase liver weight or liver-body weight ratio or lower serum triglycerides. Since hemiacetal 4 selectively influenced triglycerides in normal animals, lactone 2 and hemiacetal 4 appear to have differential hypolipidemic effects. In the Triton hyperlipidemic model 2 and 4 lowered elevated triglycerides; only 4 significantly reduced elevated cholesterol levels; but neither 2 nor 4 was as effective as clofibrate. Differences in the observed antilipidemic properties for clofibrate, 2, and 4 in the two animal models are discussed. On the basis of preliminary biological data described in this article it is concluded that tricyclic analogues 2 and 4 represent reasonable leads for the development of new antilipidemic agents.