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PubMed2002

In vitro and in vivo evaluation of Pluronic F127-based ocular delivery system for timolol maleate.

The purpose of this study was to develop Pluronic F127 (PF127) based formulations of timolol maleate (TM) aimed at enhancing its ocular bioavailability. The effect of isotonicity agents and PF127 concentrations on the rheological properties of the prepared formulations was examined. In an attempt to reduce the concentration of PF127 without compromising the in situ gelling capabilities, various viscosity enhancing agents were added to PF127 solution containing 0.5% TM. The viscosity and the ability of PF127 gels to deliver TM, in vitro, in absence and presence of various viscosity enhancing agents were also evaluated. At the used concentration, some of the examined isotonicity agents had effect on the viscosity of TM gel. However, the viscosity of gel increased as the PF127 concentrations increased. The viscosity of formulations containing thickening agents was in the order of PF-MC 3%>PF-HPMC 2%>PF-CMC 2.5%>PF127 15%. The slowest drug release was obtained from 15% PF127 formulations containing 3% methylcellulose. In vivo study showed that the ocular bioavailability of TM, measured in albino rabbits, increased by 2.5 and 2.4 fold for 25% PF127 gel formulation and 15% PF127 containing 3% methylcellulose, respectively, compared with 0.5% TM aqueous solution.

Adrenergic beta-Antagonists↗
PubMed2002

Solid-state plasticization of an acrylic polymer with chlorpheniramine maleate and triethyl citrate.

The influence of in situ plasticization of chlorpheniramine maleate (CPM) on Eudragit RS PO from hot-melt extruded matrix tablets, and from compressed granules prepared by thermal processing was investigated. CPM was studied as both a model drug substance and as a solid-state plasticizer for the acrylic polymer. Triethyl citrate (TEC) was incorporated into the polymer blend as a liquid plasticizer for the polymer. The influence of TEC and CPM concentration on the dissolution properties of CPM tablets was investigated. The glass transition temperature (T(g)) of the samples was determined by modulated differential scanning calorimetry (MDSC). The morphologies of the granules formed by hot-melt extrusion and hot-melt granulation processes were investigated by scanning electron microscopy. The addition of 12% TEC to the polymer reduced the T(g) by 32.5 degrees C, while the reduction in the T(g) for the same level of CPM was 16.4 degrees C. The effect of TEC levels on drug release was dependent on the tablet preparation method. At high TEC levels, the release rate of CPM decreased in tablets prepared by direct compression and tablets made from compressed granules that had been prepared by high shear hot-melt granulation. However, the CPM release rate increased from hot-melt extruded tablets with increasing blends of plasticizer in the extruded tablets. An increase in the CPM content in the tablets resulted in an increase in the drug release rate. During high shear hot-melt granulation, the model drug adhered to the polymer to form a porous discontinuous structure. Following hot-melt extrusion, the drug was distributed at a molecular level in the continuous polymeric structure. The influence of both CPM and TEC levels on the drug release rate from these polymeric drug delivery systems was shown to be a function of whether the granules or tablets were formed by either hot-melt granulation or hot-melt extrusion, as well as the plasticization effects of both TEC and CPM on the acrylic polymer.

Chemistry, Pharmaceutical↗
PubMed1999

Transmucosal sustained-delivery of chlorpheniramine maleate in rabbits using a novel, natural mucoadhesive gum as an excipient in buccal tablets.

The objective of this study was to evaluate the gum from Hakea gibbosa (Hakea) as a sustained-release and mucoadhesive component in buccal tablets following their application to the buccal mucosa of rabbits. Flat-faced core tablets containing either 22 or 32 mg of Hakea and 40 or 25 mg of chlorpheniramine maleate (CPM) per tablet with either sodium bicarbonate or tartaric acid in a 1:1.5 molar ratio were formulated using a direct compression technique and were coated with Cutina(R) on all but one face. The resulting plasma CPM concentration versus time profiles were determined following buccal application of the tablets in rabbits. The strength of mucoadhesion of the tablets was also quantitated in terms of the force of detachment as a function of time. Following the application of the mucoadhesive buccal tablets, the following values for several pharmacokinetic parameters were obtained. The force of detachment for the mucoadhesive buccal tablets containing 22 mg of Hakea and either 25 and 40 mg CPM, and 32 mg Hakea and 40 mg CPM increased from 1.64+/-0.47 to 7.32+/-0.34 N, 1.67+/-0.30 to 7.21+/-0.36 N, and 2.93+/-0.73 to 7.92+/-0.60 N, respectively from 5 to 90 min following application to excised intestinal mucosa. Addition of either sodium bicarbonate or tartaric acid, as well as higher amounts of CPM, did not affect the mucoadhesive bond strength. These results demonstrate that the novel, natural gum, H. gibbosa, may not only be used to sustain the release of CPM from a unidirectional-release buccal tablet, but also demonstrate that the tablets are sufficiently mucoadhesive for clinical application. The mucoadhesive strength as measured by the force of detachment, can be modulated by altering the amount of Hakea in the tablet. The mucoadhesive buccal tablets evaluated represent an improved transbuccal delivery system for conventional drug substances.

Adhesives↗
PubMed2000

Solubilization of timolol maleate in reversed micellar systems. Measurement of particle size using SAXS and PCS.

Small angle X-ray scattering (SAXS) and photon correlation spectroscopy (PCS) are two methods to measure particle sizes in the order of 10 nm magnitude, which can be used to characterize reversed micellar systems, in this case reverse micelles consisting of lecithin and isopropyl myristate (IPM). In this study these micelles are loaded with different concentrations of the amphiphilic anti-glaucoma drug timolol maleate (TM). The PCS results are consistent with those yielded by SAXS, showing a decrease of particle size with higher TM concentration. In addition, SAXS is capable to give information about the particle shape. This kind of evaluation yields an ellipsoidal shape for micelles with low drug loads, which transform into nearly spherical micelles at higher drug concentrations.

Dose-Response Relationship, Drug↗
PubMed2000

Transdermal iontophoretic delivery of timolol maleate in albino rabbits.

The use of transdermal iontophoresis is a promising technique for the systemic delivery of water soluble and ionic drugs of relatively large molecular size. The present study investigates the skin pre-treatment with Azone (laurocapram) and iontophoresis on the pharmacodynamic effect of timolol maleate (TM) in vivo in albino rabbits. The pharmacodynamic effect of TM was evaluated by transdermal delivery and compared with an intravenous (i.v.) administration. Iontophoresis of TM (0.1 mg/ml) produced a significant inhibition in the isoprenaline (ISP)-induced tachycardia. Iontophoresis with higher concentration of TM (1 mg/ml) produced a 100% inhibition of the ISP induced tachycardia. Pre-treatment of skin with Azone (3% v/v emulsion) eliminated the lag time and prolonged the duration of action of iontophoresis from 4 to 6 h. The AUC of Azone treated group was significantly higher than that of the untreated group (P<0.05). Further, the AUC with iontophoretic delivery and pre-treatment of Azone was comparable to that of intravenous TM (30 microg/kg). In conclusion, iontophoresis in combination with Azone can increase the transdermal delivery of TM, whereby the required transport rate can be achieved with a lower drug concentration.

Administration, Cutaneous↗
PubMed2002

Application of TLC-densitometry, first-derivative UV-spectrophotometry and ratio derivative spectrophotometry for the determination of dorzolamide hydrochloride and timolol maleate.

Three methods are described for the simultaneous determination of dorzolamide hydrochloride (DORZ) and timolol maleate (TIM) in ophthalmic solutions. The first method is based on application of thin layer chromatographic separation of both drugs followed by the densitometric measurements of their spot areas. After separation on silica gel GF(254) plates, using methanol-ammonia 25% (100:1.5 v/v) as the mobile phase, the chromatographic zones corresponding to the spots were scanned at 253 and 297 nm, respectively. The calibration function was established in the ranges of 2-18 microg for DORZ and 0.5-4.5 microg for TIM. The second method depends on first derivative ultraviolet spectrophotometry, with zero-crossing measurement method. The first derivative values D(1) at 250.2 and 312.5 nm were selected for the assay of DORZ and TIM, respectively. Calibration graphs follow Beer's law in the range 10-64 and 2.5-16 microg ml(-1), respectively. The third method is based on ratio first derivative spectrophotometry. The signals in the first derivative of the ratio spectra at 244 and 306.2 nm were selected to determine DORZ and TIM in the mixture and calibration graphs are linear in the range of 5-40 and 5.0-17.5 microg ml(-1), respectively. The proposed methods were successfully applied to the determination of these compounds in synthetic mixtures and in pharmaceutical preparations. The proposed methods are simple, rapid and suitable for quality control application.

Antihypertensive Agents↗
PubMed2002

Simultaneous determination of domperidone maleate and cinnarizine in a binary mixture using derivative ratio spectrophotometry and classical least squares calibration.

This work is concerned with the simultaneous determination of domperidone maleate (DOM) and cinnarizine (CINN) in a binary mixture form without previous separation by two different methods. The first method is the application of derivative ratio spectrophotometry where the linearity range was 2.5-30 micro g/ml, 2.5-25 micro g/ml for DOM and CINN, respectively, and percentage recoveries were 100.26+/-1.308 and 99.86+/-0.939 for DOM and CINN, respectively, in their laboratory prepared mixtures. The second method depends on the application of classical least squares (CLS) calibration model. Two training sets were constructed and the best model was used for the prediction of the concentrations of both drugs. The proposed procedures were successfully applied for the simultaneous determination of both drugs in laboratory prepared mixtures and in commercial tablet preparations. The validity of the proposed methods was assessed by applying the standard addition technique where the percentage recovery of the added standard was found to be 99.83+/-1.861 and 98.38+/-0.871 for DOM and CINN, respectively, using the derivative ratio method and 99.53+/-0.916 and 99.39+/-0.599 for DOM and CINN, respectively, using the CLS method. The proposed procedures are rapid, simple, require no preliminary separation steps and can, therefore, be used routine analysis of both drugs in quality control laboratories.

Antiemetics↗
PubMed2003

A chromatographic method for rapid and simultaneous analysis of codeine phosphate, ephedrine HCl and chlorpheniramine maleate in cough-cold syrup formulation.

The present paper describes a simple, accurate and precise reversed phase HPLC method for rapid and simultaneous quantification of codeine phosphate, ephedrine HCl and chlorpheniramine maleate in a cough-cold syrup formulation. Separations were carried out on a Zorbax XDB C8 column (150 x 4.6 mm ID), 5 microm particle size. A gradient elution system was developed using varying percentages of two mobile phases: methanol-glacial acetic acid-triethylamine (980:15:6 v/v) and water-glacial acetic acid-triethylamine (980:15:6 v/v). The elution of the analytes was achieved in less than 7 min with a flow rate of 1.5 ml/min. Detection was by UV absorbance at a wavelength of 254 nm. Quantification of the components in actual syrup formulations was calculated against the responses of freshly prepared external standard solutions. The method was validated and met all analysis requirements of quality assurance and quality control recommended by FDA of the USA.

Chemistry, Pharmaceutical↗
PubMed2003

Spectrophotometric and liquid chromatographic determination of trimebutine maleate in the presence of its degradation products.

Three methods are presented for the determination of trimebutine maleate (TM) in the presence of its degradation products. The first method was based on a high performance liquid chromatographic (HPLC) separation of TM from its degradation products using an ODS column at ambient temperature with a mobile phase consisting of acetonitrile-5 mM heptane sulfonic acid disodium salt (45:55, v/v, pH 4) with UV detection at 215 nm. The second method depends on using first derivative spectrophotometry (1D) by measurement of the amplitude at 252.2 nm. The third method depends on using first derivative of the ratio spectrophotometry (1DD) by measurement of the amplitude at 282.4 nm where a normalized spectrum of 3,4,5-trimethoxy benzoic acid is used as divisor. The proposed HPLC and 1D methods were used to investigate the kinetics of acidic and alkaline degradation processes. The pH-rate profile of degradation of TM in Britton-Robinson buffer solutions within the pH range 2-11.9 was studied.

Calibration↗
PubMed2003

Simultaneous determination of paracetamol and chlorpheniramine maleate by micellar electrokinetic chromatography.

A micellar electrokinetic chromatography (MEKC) method was established for determination of paracetamol (PARA) and chlorpheniramine maleate (CPM) in cold tablets. Separation of both drugs, as well as other seven cold remedy ingredients, was achieved in 25.5 min using a sodium dihydrogenphosphate-sodium tetraborate buffer (10 mM, pH 9.0) containing sodium dodecyl sulfate (SDS) (50 mM) and acetonitrile (26% v/v). The effective capillary length of 50 cm, the separating voltage of 15 kV and the temperature of 30 degrees C was optimized. Detection was by a diode array detector at 214 nm. Method linearity was excellent (r(2)>0.999) over the concentration tested (10-250 microg/ml) with good precision and accuracy. Recoveries were good (>99%) with limits of detection of 0.4 and 0.5 microg/ml and limits of quantitation of 2 (%R.S.D.=3.1%) and 4 (%R.S.D.=2.4%) microg/ml, for PARA and CPM, respectively. The developed method was applied to the determination of ingredients in cold tablets and was found to be simple, rapid and efficient.

Acetaminophen↗
PubMed1999

Simultaneous determination of cinnarizine and domepiridone maleate from tablet dosage form by reverse phase ion pair high performance liquid chromatography.

A new simple, precise, rapid and selective reverse phase ion pair high performance liquid chromatography (HPLC-RP) method has been developed for the simultaneous determination of cinnarizine (CINN) and domepiridone maleate (DOME) from tablets using acetonitrile-methanol-water-0.1 N sulfuric acid (37:10:48:5 v/v/v/v) containing sodium lauryl sulfate (0.01 M), as a mobile phase and a Machery Nagel nitrile column (10 microns, 25 cm x 4.0 mm i.d.) as the stationary phase. The flow of mobile phase through the column was kept at 1.0 ml min(-1) through out the analysis. Detection was carried out using a UV detector at 225 nm. The retention times for CINN and DOME were 4.73 and 9.41 min, respectively. The linearity range and percentage recoveries for CINN and DOME were 4 1000 and 60-750 microg ml(-1) and 99.90 and 99.60%, respectively.

Calcium Channel Blockers↗
PubMed2002

ST-segment elevation and ventricular fibrillation without coronary spasm by intracoronary injection of acetylcholine and/or ergonovine maleate in patients with Brugada syndrome.

OBJECTIVES: The study examined whether patients with Brugada syndrome are sensitive to vagal stimulation or ischemia. BACKGROUND: Experimental studies have suggested that a prominent transient outward current (I(to))-mediated action potential notch and a subsequent loss of the action potential dome in the epicardium, but not in the endocardium, give rise to ST-segment elevation and subsequent ventricular fibrillation (VF). METHODS: We evaluated the frequency of coronary spasm, augmentation (> or =0.1 mV) of ST-segment elevation in leads V(1) to V(3), and induction of VF by intracoronary injection of acetylcholine (ACh) and/or ergonovine maleate (EM) in 27 symptomatic patients with Brugada syndrome and 30 control subjects. RESULTS: The coronary spasm was induced in 3 (11%) of the 27 patients with Brugada syndrome and in 13 (43%) of the 30 control subjects. ST-segment elevation was augmented by 11 (33%) of the 33 right coronary injections (ACh: 6/11 [55%]; EM: 5/22 [23%]), without coronary spasm, but not by any of the left coronary injections in patients with Brugada syndrome. Ventricular fibrillation was induced by 3 (9%) of the 33 right coronary injections (ACh: 2/11 [18%]; EM: 1/22 [5%]), but not by any of the left coronary injections. In contrast, neither ST-segment elevation nor VF was observed in any of the control subjects. CONCLUSIONS: Our results support the hypothesis that mild ischemia and vagal influences act additively or synergistically with the substrate responsible for the Brugada syndrome to elevate the ST-segment and precipitate VF. These observations suggest that Brugada patients may be at a higher risk for ischemia-related sudden death.

Acetylcholine↗
PubMed1998

Polymorphism and desolvation of flupirtine maleate.

Crystallizates of the analgesic agent flupirtine maleate (Katadolon; ASTA Medica, Dresden, Germany) obtained from isopropanol are examined by X-ray diffractometry, polarization microscopy and thermoanalysis. Depending on the crystallizing conditions, the modifications A and B as well as an isopropanol solvate are observed. The inversion temperature A-->B of the enantiotropic modifications is 164 degrees C (differential scanning calorimetry (DSC) onset). During thermal desolvation, modification B is formed well below the inversion temperature. In concentrated isopropanol suspensions, the solvate and modification B are rapidly transformed into modification A. It is shown how phase-pure products consisting of modification A, which is better wettable with water and stable at room temperature, can be obtained.

Aminopyridines↗
PubMed1991

A new class of calcium antagonists. 2. Synthesis and biological activity of 11-[[4-[4-(4-fluorophenyl)-1-piperazinyl]butyryl]amino]-6,11- dihydrodibenzo[b,e]-thiepin maleate and related compounds.

A series of [(epsilon-aminoalkanoyl)amino]-6,11- dihydrodibenzo[b,e]thiepins and -5H-dibenzo[a,d]cycloheptenes and related compounds were synthesized and evaluated for calcium antagonistic activity by calcium-induced constriction of potassium-depolarized rat aorta. Semiempirical molecular orbital calculations of the dibenzotricyclic systems indicated that calcium antagonistic activity increased with a decrease of the angle between the planes of the two phenyl rings. AM1 net charge calculations showed that a neutral or positive charge distribution in the bridge portion was necessary for activity. 11-[[4-[4-(4-Fluorophenyl)-1- piperazinyl]butyryl]amino]-6,11-dihydrodibenzo[b,e]thiepin maleate (16, AJ-2615) showed a more gradual and longer lasting antihypertensive effect than diltiazem and nifedipine in spontaneously hypertensive rats (SHR) administered orally. Compound 16 also possessed antianginal effects in methacholine-induced ST elevation and vasopressin-induced ST depression tests in rats. The alteration of the dibenzotricyclic system of 16 to 5H-dibenzo[a,d]cycloheptene (19, 5-[[4-[4-(4-fluorophenyl)-1-piperazinyl]-butyryl]amino]-5H- dibenzo[a,d]cycloheptene) resulted in selectivity for cardiac tissue over vascular tissue, thereby conferring antianginal activity without an effect on blood pressure. Antianginal potencies of 16 and 19 were equal to or somewhat more potent than those of diltiazem.

Animals↗
PubMed1996

Structure-activity relationships of a series of novel (piperazinylbutyl)thiazolidinone antipsychotic agents related to 3-[4-[4-(6-fluorobenzo[b]thien-3-yl)-1-piperazinyl]butyl]-2,5,5- trimethyl-4-thiazolidinone maleate.

HP-236 (3-[4-[4-(6-Fluorobenzo[b]thien-3-yl)-1-piperazinyl]butyl]-2,5,5- trimethyl-4-thiazolidinone maleate; P-9236) (54) displayed a pharmacological profile indicative of potential atypical antipsychotic activity. A series of piperazinyl butyl thiazolidinones structurally related to this compound were prepared and evaluated in vitro for dopamine D2 and serotonin 5HT2 and 5HT1A receptor affinity. The compounds were examined in vivo in animal models of potential antipsychotic activity and screened in models predictive of extrapyramidal side effect (EPS) liability. The synthesis of these compounds, details of their structure-activity relationships, and discovery of a new lead, compound 50, as well as further development of the profiles of compounds 50 and 54 are described.

Animals↗
PubMed2006

Study on the synthesis of poly(diglycidyl maleate-co-stearyl methacrylate) and morphology conversion of their self-assembly systems.

A novel polymer of poly(diglycidyl maleate-co-stearyl methacrylate) (P(DGMA-co-SMA)) was synthesized by reaction between poly(maleic anhydride-co-stearyl methacrylate) (P(MA-co-SMA)) and epichlorohydrin. The self-assembly behavior of the resultant copolymer was investigated. It was found that the spheral aggregates could converse to nanorods after being aged for 2.5 days and nanolines composed of the nanorods were obtained after being aged for an additional 5.5 days. The mechanism of their self-assembly behavior and morphology conversion of self-assembly systems is discussed.

Magnetic Resonance Spectroscopy↗
PubMed1998

Maleation of Poly(4-methyl-1-pentene) Using Supercritical Carbon Dioxide.

The heterogeneous free-radical grafting of maleic anhydride (MAH) onto poly(4-methyl-1-pentene) (PMP) was studied using supercritical carbon dioxide as the solvent/swellant. The anhydride content in the product can be controlled by using variations in time and temperature to achieve maleations as high as 7 mol % at 125 degreesC after a 5 h reaction period. A comparison between benzoyl peroxide (BPO) and dicumyl peroxide (DCP) initiators indicates that DCP is the more effective initiator. The effect of reactant concentrations on the degree of grafting is also examined, yielding an optimum MAH:DCP molar ratio of 3:2. Competitive cross-linking of the substrate is the major drawback to this means of polymer modification.

Journal Article↗