Y-site stability of fosphenytoin and sodium phenobarbital.

Fosphenytoin and sodium phenobarbital in 0.9% sodium chloride injection were analyzed in a simulated Y-site admixture. Each drug was analyzed for stability by high-pressure liquid chromatography (HPLC) from three simulated Y-site samples over an eight-hour period. The HPLC assay results indicate that both fosphenytoin and sodium phenobarbital are stable together at a Y site over an eight-hour period. In addition, there was no change in sample clarity or pH over the same period. The results indicate that, when medically necessary, fosphenytoin and sodium phenobarbital in 0.9% sodium chloride injection can be administered via the same intravenous line.

Fosphenytoin y-site stability studies with Lorazepam and midazolam hydrochloride.

The treatment of status epilepticus may require in certain situations the concurrent administration of lorazepam or midazolam with fosphenytoin. Simulated Y-site fosphenytoin/lorazepam and fosphenytoin/midazolam hydrochloride admixtures, respectively, in 0.9% sodium chloride injection were analyzed using a stability-indicating high-performance liquid chromatography (HPLC) method. Each drug was analyzed for stability by HPLC from three simulated Y-site samples over an eight-hour period. The HPLC assay results indicate that both fosphenytoin and lorazepam are stable together at a Y site over an eight-hour period. In addition, there was neither a change in sample clarity nor a change in pH over the same period. The results indicate that, when medically necessary, fosphenytoin and lorazepam in 0.9% sodium chloride injection can be administered via the same intravenous (IV) line. Midazolam free base was precipitated upon admixture of midazolam hydrochloride and fosphenytoin solutions. Therefore, midazolam hydrochloride and fosphenytoin should not be given via the same IV line.

Stability of Dobutamine Hydrochloride 4mg/mL in 5% Dextrose Injection at 5 and 23 deg C.

The stability of dobutamine hydrochloride 4 mg/mL in 5% dextrose injection has been studied using a stability-indicating, high-performance liquid chromatography assay method. The admixture injections were stable for 30 days at 5 and 23 deg C. Concentrations ranged between 98.5% and 102.6% for the room-temperature samples, and 99.6% and 101.8% for the refrigerated samples, of the initial mean concentrations. The standard curves demonstrated linearity (r2>.999). Variations within and between days were less than 3%. None of the samples appeared to form a visible precipitate or changed in color or clarity and the pH of the samples remained between 3.5 and 3.7.

Evaluation of cis- and trans-9- and 11-hydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a]phenanthridines as structurally rigid, selective D1 dopamine receptor ligands.

The present study reports the investigation of the D1 structure-relationships of certain cis- or trans-9- or 11-monohydroxy analogues of (+/-)-trans-10,11-dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a] phenanthridine (8a, dihydrexidine), previously identified as the first full efficacy D1 dopamine receptor agonist. The monohydroxybenzo[a]phenanthridines were prepared from the appropriately substituted beta-tetralones using the methods described earlier for the synthesis of their catechol analogues. The 10-bromo 11-hydroxy derivative 9e was prepared by treatment of precursor 9c with bromine in chloroform. The affinities of these compounds for the D1 and D2 dopamine receptor classes and for their effects on adenylate cyclase activity were assessed in rat striatal membranes. In addition to producing only minimal increases in adenylate cyclase activity (< or = 15%), these phenolic derivatives generally had significantly lower affinities for D1 and D2 receptors (D1 IC50 > or = 102 nM, D2 IC50 > or = 210 nM) than did their catechol analogues. Further, compounds bearing a cis B/C-ring fusion displayed lower affinities than those bearing a trans configuration, paralleling the activity differences between the catechol analogues. The data for these rigid dopamine receptor ligands from the benzo[a]phenanthridine class lend additional support for the hypothesis that D1 agonist activity is optimized by a trans ring configuration that maintains the beta-phenyldopamine substructure in the "trans-beta-rotamer."

Direct determination of cotinine-N-glucuronide in urine using thermospray liquid chromatography/mass spectrometry.

A thermospray liquid chromatographic/mass spectrometric method has been developed for direct determination of cotinine-N-glucuronide in the urine of smokers. Quantification was performed using methyl-d3-cotinine-N-glucuronide as internal standard and monitoring the protonated aglycons. Using a simple preparation, urine samples from four smokers were analyzed and the results compared favorably with those from a previously reported method that quantifies aglycon release following beta-glucuronidase treatment. Amounts of cotinine-N-glucuronide found in urine from smokers ranged from less than 0.7 to 21 nmol ml-1, indicating wide inter-individual variability in the metabolic production of this metabolite. Cotinine-N-glucuronide was found to be the second most abundant urinary nicotine metabolite. A similar method was developed for trans-3'-hydroxycotinine-N-glucuronide but this compound was not detected in smokers' urine.

Characterization of the glucuronide conjugate of cotinine: a previously unidentified major metabolite of nicotine in smokers' urine.

Recent studies in our laboratories have confirmed that a major unidentified metabolite of nicotine in smokers' urine was susceptible to enzymatic degradation by beta-glucuronidase to afford (S)-(-)-cotinine. In order to establish the identity of this metabolite, the quaternary ammonium conjugate, viz., (S)-(-)-cotinine N-glucuronide, was synthesized. Reaction of methyl 2,3,4-tri-O-acetyl-1-bromo-1-deoxy-alpha-D-glucopyranuronate with (S)-(-)-cotinine at 60 degrees C for 3 days affords the fully protected conjugate as the bromide salt. Deprotection was accomplished in 1 M NaOH overnight at 25 degrees C. The deprotected inner salt was isolated by Dowex-50W cation-exchange chromatography. Electrospray mass spectra of the inner salt revealed the presence of ions with m/z 353 (M + H)+, 375 (M + Na)+, and 391 (M + K)+ as well as ions resulting from loss of water and cleavage of the glycosidic bond. Proton and carbon nuclear magnetic resonance spectra established that the position of glucuronidation was the pyridyl nitrogen. The magnitude of the coupling between H1" and H2" of the sugar ring (8.71 Hz) and nuclear Overhauser enhancements were consistent with the beta-isomer of the glucuronide conjugate. The synthetic (S)-(-)-cotinine N-glucuronide was susceptible to enzymatic hydrolysis by beta-glucuronidase to afford (S)-(-)-cotinine. Application of a cation-exchange high-performance liquid chromatographic method enabled the collection of a fraction containing (S)-(-)-cotinine N-glucuronide from a smoker's urine. The electrospray mass spectrum of this fraction contained ions consistent with the presence of (S)-(-)-cotinine N-glucuronide. The concentrated fraction was subjected to enzymatic hydrolysis by beta-glucuronidase to afford (S)-(-)-cotinine.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and anti-HIV activity of 4'-thio-2',3'-dideoxynucleosides.

A series of 2',3'-dideoxy-4'-thionucleoside analogues of purines and pyrimidines, including 4'-thioddI (17), 4'-thioddC (27), and 4'-thioAZT (34), were synthesized and evaluated for their inhibitory activity against human immunodeficiency virus (HIV). A stereospecific synthesis of the 2,3-dideoxy-4-thioribofuranosyl carbohydrate precursor 11 starting with L-glutamic acid is described. 2',3'-Dideoxy-4'-thiocytidine (27) displayed significant, but modest activity in vitro against human immunodeficiency virus.

trans-10,11-dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a]phenanthridine: a highly potent selective dopamine D1 full agonist.

trans-10,11-Dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a]phenan thridine (4a, dihydrexidine) has been found to be a highly potent and selective agonist of the dopamine D1 receptor in rat brain. Dihydrexidine had an EC50 of approximately 70 nM in activating dopamine-sensitive rat striatal adenylate cyclase and a maximal stimulation equal to or slightly greater than that produced by dopamine. Dihydrexidine had an IC50 of 12 nM in competing for [3H]SCH23390 (1a) binding sites in rat striatal homogenate, and of 120 nM versus [3H]spiperone. These data demonstrate that dihydroxidine has about ten-fold selectivity for D1/D2 receptors. More importantly, however, is the fact that dihydrexidine is a full agonist. Previously available agents, such as SKF38393 (1b), while being somewhat more selective for the D1 receptor, are only partial agonists. The isomeric cis-dihydroxybenzo[a]-phenanthridine neither stimulated cAMP synthesis nor inhibited the cAMP synthesis induced by dopamine. The cis isomer also lacked appreciable affinity for [3H]-1a binding sites. N-Methylation of the title compound decreased affinity for D1 sites about 7-8-fold and markedly decreased ability to stimulate adenylate cyclase. Addition of an N-n-propyl group reduced affinity for D1 sites by about 50-fold and essentially abolished the ability to stimulate adenylate cyclase. However, this latter derivative had twice the affinity of the D2-selective agonist quinpirole for the D2 receptor. The results are discussed in the context of a conceptual model for the agonist state of the D1 receptor.

Nonneurotoxic tetralin and indan analogues of 3,4-(methylenedioxy)amphetamine (MDA).

Four cyclic analogues of the psychoactive phenethylamine derivative 3,4-(methylenedioxy)amphetamine were studied. These congeners, 5,6- and 4,5-(methylenedioxy)-2-aminoindan (3a and 4a, respectively), and 6,7- and 5,6-(methylenedioxy)-2-aminotetralin (3b and 4b, respectively) were tested for stimulus generalization in the two-lever drug-discrimination paradigm. Two groups of rats were trained to discriminate either LSD tartrate (0.08 mg/kg) from saline, or (+/-)-MDMA.HCl (1.75 mg/kg) from saline. In addition, a 2-aminoindan (5a) and 2-aminotetralin (5b) congener of the hallucinogenic amphetamine 1-(2,5-dimethoxy-4- methylphenyl)-2-aminopropane (DOM) were also evaluated. None of the methylenedioxy compounds substituted in LSD-trained rats, while both 3a and 3b fully substituted in MDMA-trained rats. Compounds 4a and 4b did not substitute in MDMA-trained rats. Compounds 5a and 5b did not substitute in MDMA-trained rats, although 5a substituted in LSD-trained rats, but with relatively low potency compared to its open-chain counterpart. In view of the now well-established serotonin neurotoxicity of 3,4-(methylenedioxy)amphetamine and its N-methyl homologue 1, 3a and 3b were evaluated and compared to 1 for similar toxic effects following a single acute dose of 40 mg/kg sc. Sacrifice at 1 week showed that neither 3a nor 3b depressed rat cortical or hippocampal 5-HT or 5-HIAA levels nor were the number of binding sites (Bmax) depressed for [3H]paroxetine. By contrast, and in agreement with other reports, 1 significantly depressed all three indices of neurotoxicity. These results indicate that 3a and 3b have acute behavioral pharmacology similar to 1 but that they lack similar serotonin neurotoxicity.

Evaluation of isomeric 4-(chlorohydroxyphenyl)-1,2,3,4-tetrahydroisoquinolines as dopamine D-1 antagonists.

The isomeric 4-(3-chloro-4-hydroxyphenyl)- and 4-(4-chloro-3-hydroxyphenyl)-1,2,3,4-tetrahydroisoquinolines, the N-methyl derivative of the 4-(4-chloro-3-hydroxyphenyl) isomer, and 4-(3-hydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline were synthesized and evaluated for dopamine D-1 antagonist activity. The 4-(3-chloro-4-hydroxyphenyl) and the 4-(3-hydroxyphenyl) isomer possessed similar potencies as D-1 antagonists. Introduction of the N-methyl group enhanced potency about twofold. The "pharmacophore" for selective dopamine D-1 antagonist activity appears to be a tertiary 2-(3-hydroxyphenyl)-2-phenethylamine.

Effect of beta-alkyl substitution on D-1 dopamine agonist activity: absolute configuration of beta-methyldopamine.

beta-Methyldopamine and its enantiomers and racemic beta-phenyldopamine were synthesized and evaluated for dopamine D-1 agonist activity. In the dopamine-sensitive adenylate cyclase assay, beta-phenyldopamine had about one-sixth the activity of dopamine. Racemic beta-methyldopamine was less potent. The absolute configuration of beta-methyldopamine was determined to be R-(+) and S-(-). Evaluation of (R)-(+)- and (S)-(-)-beta-methyldopamine revealed no enantioselectivity for stimulation of adenylate cyclase.

Specific dopamine D-1 and DA1 properties of 4-(mono- and -dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline and its tetrahydrothieno[2,3-c]pyridine analogue.

The title compounds were prepared and examined to elucidate further the structure-activity relationships of dopamine agonists related to nomifensine. Two of the compounds, 4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline and 4-(3,4-dihydroxyphenyl)-1,2,3,4-tetrahydrothieno[2,3-c]pyridine, have been reported in the patent literature. In stimulation of rat retinal adenylate cyclase, a measure of dopamine D-1 agonist activity, the tetrahydroisoquinoline was about equipotent to dopamine. The thienyl isostere had nearly twice the potency. Both compounds were potent vasodilators in the canine renal artery, producing dilation through stimulation of DA1 type peripheral dopamine receptors. A monohydroxy analogue, 4-(3-hydroxyphenyl)-1,2,3,4-tetrahydroisoquinoline, had only slight activity in the cyclase assay and was inactive in the canine renal artery. These results, combined with those from an earlier study, demonstrate that N-alkylation decreases both dopamine D-1 and DA-1 agonist potency, with activity ordered as H greater than methyl greater than ethyl greater than propyl. The results also demonstrate the necessity for the catechol function in this series.

Synthesis and evaluation of 2,3-dihydrobenzofuran analogues of the hallucinogen 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane: drug discrimination studies in rats.

Two analogues, 6-(2-aminopropyl)-5-methoxy-2,3-dihydrobenzofuran and 6-(2-aminopropyl)-5-methoxy-2-methyl-2,3-dihydrobenzofuran, of the hallucinogenic agent 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) were synthesized and tested in the two-lever drug discrimination paradigm. In rats trained to discriminate saline from LSD tartrate (0.08 mg/kg), stimulus generalization occurred to both of the 2,3-dihydrobenzofuran analogues but at doses more than 10-fold higher than for DOM. A possible explanation for this dramatic attenuation of LSD-like activity could involve a highly directional electrophilic binding site on the receptor that cannot accept the orientation of the unshared electron pairs on the heterocyclic oxygen atom in the benzofurans.