Solubility of (+/-)-ibuprofen and S (+)-ibuprofen in the presence of cosolvents and cyclodextrins

Aqueous solubility is an important parameter for the development of liquid formulations and in the determination of bioavailability of oral dosage forms. Ibuprofen (IB), a nonsteroidal anti-inflammatory drug, is a chiral molecule and is currently used clinically as a racemate (racIB). However, the S form of ibuprofen or S(+)-ibuprofen (SIB) is the biologically active isomer and is primarily responsible for the antiinflammatory activity. Phase solubility studies were carried out to compare the saturation solubilities of racIB and SIB in the presence of common pharmaceutical solvents such as glycerol, sorbitol solution, propylene glycol (PG), and polyethylene glycol (PEG 300) over the range of 20% to 80% v/v in aqueous based systems. The solubilities of the two compounds were also compared in the presence of cyclodextrins such as beta cyclodextrin (CD), hydroxypropyl beta cyclodextrin (HPCD), and beta cyclodextrin sulfobutyl ether sodium salt (CDSB) over the range of 5% to 25% w/v. Solubility determinations were carried at 25 degrees C and 37 degrees C. Cosolvents exponentially increased the solubility of both SIB and racIB, especially in the presence of PG and PEG 300. Glycerol was not very effective in increasing the aqueous solubilities of both compounds, whereas sorbitol solution had a minimal effect on their solubility. PG and PEG 300 increased the solubility of SIB by 400-fold and 1500-fold, respectively, whereas the rise in solubility for racIB was 193-fold and 700-fold, respectively, at 25 degrees C for the highest concentration of the cosolvents used (80% v/v). Of the two compounds studied, higher equilibrium solubilities were observed for SIB as compared with racIB. The derivatized cyclodextrins increased the aqueous solubility of racIB and SIB in a concentration-dependent manner giving AL type of phase diagrams. The phase solubility diagrams indicated the formation of soluble inclusion complexes between the drugs and HPCD and CDSB, which was of 1:1 stoichiometry. The addition of underivatized CD reduced the solubility of racIB and SIB via the formation of an insoluble complex. The S form formed more stable complexes with HPCD and CDSB as compared with raclB. The solubilization process is discussed in terms of solvent polarity and differential solid-state structure of raclB and SIB. The thermodynamic parameters for the solubilization process are presented.     

Stability of acetazolamide in suspension compounded from tablets

The stability of acetazolamide in an extemporaneous suspension compounded from tablets was studied. Acetazolamide 25-mg/mL suspension was prepared by levigating the comminuted 250-mg tablets with 70% sorbitol solution. The mixture was incorporated into a suspension vehicle containing magnesium aluminum silicate and carboxymethylcellulose sodium. Appropriate sweeteners, flavoring agents, preservatives, humectants, and pH adjusters were then added. The suspension was stored in amber glass bottles at 5, 22, 30, 40, and 50 degrees C. Samples were analyzed for the concentration of acetazolamide by stability-indicating high-performance liquid chromatography on days 3, 7, 11, 18, 24, 32, 42, 54, and 79. For batches stored at 5, 22, and 30 degrees C, the initial acetazolamide concentration was maintained during the entire 79 days of the study. However, the concentrations in the batches stored at 40 and 50 degrees C were below 90% of the initial value after 79 and 32 days, respectively. The Arrhenius plot was used to predict a shelf life of the suspension at room temperature of 371 days. Acetazolamide oral suspension 25 mg/mL was stable for at least 79 days at 5, 22, and 30 degrees C. The formulation should be maintained at pH 4-5 and stored in amber glass bottles.     

Effect of pH, chlorobutanol, cysteine hydrochloride, ethylenediaminetetraacetic acid, propylene glycol, sodium metabisulfite, and sodium sulfite on furosemide stability in aqueous solutions

A study was conducted to determine the effects of pH, two antioxidants, a chelating agent, a preservative, and propylene glycol on furosemide stability. Aqueous solutions of furosemide containing 10% alcohol (v/v) were prepared in phosphate buffers with various pH values (5, 6, and 9) whose ionic strength was adjusted to 0.1 M with potassium chloride. Some solutions contained chlorobutanol, ethylenediaminetetraacetic acid, or sodium metabisulfite. Another set of aqueous solutions contained phosphate buffer (0.1 M), alcohol (10% v/v), and propylene glycol (40% v/v) with or without cysteine hydrochloride, ethylenediaminetetraacetic acid, and sodium sulfite. The solutions were divided into two parts, stored at 24 and 50 degrees, and assayed frequently using a previously developed high-pressure liquid chromatographic procedure. At the lowest pH value (pH 5), furosemide appeared to be very unstable. Cysteine hydrochloride, ethylenediaminetetraacetic acid, and sodium sulfite failed to improve the stability of furosemide. Chlorobutanol and sodium metabisulfite had an adverse effect on the stability, probably due to the fact that they decreased the pH of the solution. The pH value appears to be the only critical factor for the stability of furosemide. Buffered solutions containing propylene glycol were very stable at both temperatures for 170 days, and they tasted good.     

Stability of pediatric liquid dosage forms of ethacrynic acid, indomethacin, methyldopate hydrochloride, prednisone and spironolactone

The stability of liquid dosage forms of ethacrynic acid (1 mg/ml), indomethacin (2 mg/ml), methyldopate hydrochloride (25 mg/ml), prednisone (0.5 mg/ml) and spironolactone (2 mg/ml), which often are compounded extemporaneously, was studied. One or two liquid dosage forms of each of the five drugs was prepared with the pure drug or the powder from a commercial dosage form using aqueous sorbitol or simple syrup alone or with a 10% (v/v) solution of alcohol in water. The dosage forms were stored at 24 C in amber-colored bottles for 21-224 days and assayed by various methods. All solutions studied were stable for at least 84 days. A solution was considered stable if it retained 90% of its drug concentration. Except for the prednisone solution, all solutions were stable for at least 164 days; however, the solution of methyldopate hydrochloride prepared from the pure drug became discolored after 98 days. The liquid dosage forms studied have limited stability but can be used by the pharmacist when extemporaneous oral solutions of these drugs are needed.     

Solubility and stability of melatonin in propylene glycol and 2-hydroxypropyl-β-cyclodextrin vehicles

The physicochemical properties of melatonin (MT) in propylene glycol (PG) and 2-hydroxypropyl-beta-cyclodextrin (2-HPbetaCD) vehicles were characterized. MT was endothermally decomposed as determined by differential scanning calorimetry (DSC). Melting point and heat of fusion obtained were 116.9+/-0.24 degrees C and 7249+/-217 cal/mol, respectively. MT as received from a manufacture was very pure, at least 99.9%. The solubility of MT in PG solution increased slowly until reaching 40% PG and then steeply increased. Solubility of MT increased linearly as concentration of 2-HPbetaCD without PG increased (R(2)=0.993). MT solubility in the mixtures of PG and 2-HPbetaCD also increased linearly but was less than the sum of its solubility in 2-HPbetaCD and PG individually. The MT solubility was low in water, simulated gastric or intestinal fluid but the highest in the mixture of PG (40 v/v%) and 2-HPbetaCD (30 w/v%) although efficiency of MT solubilization in 2-HPbetaCD decreased as the concentration of PG increased. MT was degraded in a fashion of the first order kinetics (r(2)>0.90). MT was unstable in strong acidic solution (HCl-NaCl buffer, pH 1.4) but relatively stable in other pH values of 4 approximately 10 at 70 degrees C. In HCl-NaCl buffer, MT in 10% PG was more quickly degraded and then slowed down at a higher concentration. However, the degradation rate constant of MT in 2-HPbetaCD was not changed significantly when compared to the water. The current studies can be applied to the dosage formulations for the purpose of enhancing percutaneous absorption or bioavailability of MT.     

Micelle-mediated extraction and cloud point preconcentration for the analysis of aesculin and aesculetin in Cortex fraxini by HPLC

In this paper, a micelle-mediated extraction and cloud point preconcentration method was developed for the determination of less hydrophobic compounds aesculin and aesculetin in Cortex fraxini by HPLC. Non-ionic surfactant oligoethylene glycol monoalkyl ether (Genapol X-080) was employed as the extraction solvent. Various experimental conditions were investigated to optimize the extraction process. Under optimum conditions, i.e. 5% Genapol X-080 (w/v), pH 1.0, liquid/solid ratio of 400:1 (ml/g), ultrasonic-assisted extraction for 30 min, the extraction yield reached the highest value. For the preconcentration of aesculin and aesculetin by cloud point extraction (CPE), the solution was incubated in a thermostatic water bath at 55 degrees C for 30 min, and 20% NaCl (w/v) was added to the solution to facilitate the phase separation and increase the preconcentration factor during the CPE process. Compared with methanol, which was used in Chinese Pharmacopoeia (2005 edition) for the extraction of C. fraxini, the extraction efficiency of 5% Genapol X-080 reached higher value.     

Isocratic RP-HPLC method for rutin determination in solid oral dosage forms

A rapid and sensitive assay for quantitative determination of rutin in oral dosage forms based on isocratic reversed phase high performance liquid chromatography (RP-HPLC) was developed and validated. Using a C(18) reverse-phase analytical column, the following conditions were chosen as optimal: mobile phase methanol-water 1:1 (v/v), pH 2.8 (adjusted with phosphoric acid), flow rate=1 mL min(-1) and temperature T=40.0 degrees C. Linearity was observed in the concentration range 8-120 microg mL(-1) with a correlation coefficient of 0.99982 and the limit of detection (LOD)=2.6 microg mL(-1), and limit of quantification (LOQ)=8.0 microg mL(-1). Intra- and inter-day precision were within acceptable limits. Robustness test indicated that the mobile phase composition and pH influence mainly the separation. The proposed method allowed direct determination of rutin in pharmaceutical dosage forms in the presence of excipients, but is not suitable for preparations where compounds structurally/chemically related to rutin may be present.     

Development and validation of a new HPLC method for determination of lamotrigine and related compounds in tablet formulations

A simple HPLC method was developed and validated for quantitation of lamotrigine and its related substances which may coexist in solid pharmaceutical dosage forms. The HPLC separation was achieved on a C18 mu-Bondapack column (250 mm x 4.6 mm) using a mobile phase of acetonitrile-monobasic potassium phosphate solution (35:65, v/v) containing orthophosphoric acid to adjust pH to 3.5 at a flow rate of 1.5 ml/min. The UV detector was operated at 210 nm, and column temperature was adjusted at 40 degrees C. The method was validated for specificity, linearity, precision, accuracy, robustness and limit of quantitation. The degree of linearity of the calibration curves, the percent recoveries of lamotrigine and related substances, the limit of detection and quantitation, for the HPLC method were determined. The method was found to be simple, specific, precise, accurate, and reproducible. The method was applied for the quality control of commercial lamotrigine tablets to quantify the drug and its related substances and to check the formulation content uniformity.     

Evaluation of antitumor and toxic side effects of mitomycin C-estradiol conjugates

The antitumor and toxic side effects of mitomycin C-estradiol conjugates (EB-glu-MMC and E-glu-MMC) were evaluated in detail for solutions in propylene glycol and suspensions in 10% (v/v) propylene glycol. Tumor growth, body weight and number of leukocytes were examined after i.p. administration to sarcoma 180 solid tumor-bearing mice. Body weight and number of leukocytes were also examined in normal mice after i.p. administration of the solution. In solution dosage forms, the two conjugates had almost the same suppressive effect on tumor growth at 30 mg MMC eq./kg as MMC at 5 mg/kg, did not lower body weight significantly, but reduced the number of leukocytes at 30 mg MMC eq./kg. MMC, lethally toxic at 10 mg, significantly lowered the body weight and leukocyte number. In the suspension dosage forms, these conjugates had a greater suppressive effect on tumor growth at 50 mg MMC eq./kg than MMC at 5 mg/kg, and reduced the body weight and leukocyte number, with E-glu-MMC more toxic than EB-glu-MMC. The presence of the tumor itself influenced the body weight and leukocyte number. However, toxic side effects could be evaluated from the body weight and leukocyte number to almost the same extent between tumor-bearing and normal mice.     

Polyethylene glycol-induced precipitation of interferon alpha-2a followed by vacuum drying: Development of a novel process for obtaining a dry, stable powder

Feasibility studies were performed on the development of a novel process based on polyethylene glycol (PEG)-induced precipitation of proteins followed by vacuum drying in the presence of sugars to obtain dry protein powders. Apparent solubility of interferon alpha-2a (IFNalpha2a) was determined in the presence of various PEGs and the effect of solution pH, ionic strength, and temperature was investigated. IFNalpha2a precipitate was dried at a shelf temperature of 25 degrees C at 100 mTorr either as it is or in the presence of mannitol and/or trehalose. The dried IFNalpha2a formulations were subjected to accelerated stability studies at 40 degrees C (3 months), and the stability was compared with that of a similar lyophilized formulation. The results indicated that more than 90% of the protein could be precipitated using 10% wt/vol PEG the protein could be precipitated using 10% wt/vol PEG 1450 at pH 6.5 at a solution ionic strength of 71 mM. Vacuum drying of the precipitate only resulted in the formation of insoluble aggregates of IFNalpha2a; however, this was prevented by the addition of either mannitol or trehalose. The addition of excess mannitol resulted in low residual moisture content and better handling of the final dried product. Accelerated storage stability did not show any aggregation and showed less than 5% formation of oxidized IFNalpha2a in the dried formulation containing IFNalpha2a: trehalose: mannitol in a 1:10:100 wt/wt ratio upon storage at 40 degrees C for 3 months. The stability of this vacuum dried formulation was comparable with that of a similar lyophilized formulation.     

Characterization of itraconazole/2-hydroxypropyl-beta-cyclodextrin inclusion complex in aqueous propylene glycol solution

The interaction of itraconazole, a triazole antifungal agent, with 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) in water and 10% v/v propylene glycol/water solution at pH 2.0 was investigated by the solubility method and ultraviolet and 1H-nuclear magnetic resonance (NMR) spectroscopies. The solubility of itraconazole in water significantly increased as the concentrations of HP-beta-CyD were augmented, showing an AP type phase solubility diagram. The upward curvature closely corresponded to the simulation curve which was calculated on the basis of the 1:2 (guest:host) complexation model. The 1:2 complex was formed even in the presence of 10% v/v propylene glycol, although the co-solvent system made the interaction with HP-beta-CyD weaker due to the competitive inclusion. The ultraviolet spectroscopic studies also supported the 1:2 complex formation of itraconazole with HP-beta-CyD in 10% v/v propylene glycol/water solution at pH 2.0. The 1H-NMR spectroscopic studies suggested that the triazole and triazolone moieties of itraconazole are involved in the 1:2 inclusion complexation.Copyright     

Compatibility of imipenem-cilastatin sodium with commonly used intravenous solutions

The stability of imipenem-cilastatin sodium (Primaxin, Merck Sharp & Dohme) in various intravenous fluids was determined after storage at 4 degrees C or 25 degrees C and after freezing. Samples of imipenem-cilastatin sodium were constituted with 100 mL of each of 17 i.v. fluids to concentrations of 2.5 mg/mL or 5.0 mg/mL of each drug component and stored in glass infusion bottles at constant room temperature (25 degrees C) or constant refrigerated temperature (4 degrees C). The concentration of each solution was determined immediately after constitution by a stability-indicating high-performance liquid chromatographic assay; the concentrations of both drugs were monitored in each i.v. fluid until the time that the concentration of either imipenem or cilastatin decreased to less than 90% of the initial concentration (t90). The exact value of t90 was determined for each solution by linear regression. The solutions were also assessed for changes in pH or color. Cilastatin sodium was more stable in all 17 i.v. fluids than imipenem. The stability of imipenem was dependent on the concentration of that drug in solution; solutions of imipenem 2.5 mg/mL were more stable than solutions of imipenem 5.0 mg/mL. The values of t90 for imipenem in solutions stored at 4 degrees C were greater than the values for solutions stored at 25 degrees C. Imipenem was most stable in 0.9% sodium chloride injection. The pH values of the solutions generally decreased during the study period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nanoparticles bearing polyethyleneglycol-coupled transferrin as gene carriers: preparation and in vitro evaluation

The aims of this work were to determine the stability of pDNA against various conditions during microencapsulation, prepare transferrin (TF)-conjugated PEGylated polycyanoacrylate nanoparticles (TF-PEG-nanoparticles), and assess its physicochemical characteristics and in vitro targeting cells association. The open circular forms of pDNA obviously increased when pDNA was emulsified into organic solution under sonification. When pDNA solution (pH 7.0) contained 1, 3 or 5% (w/v) PVA, after sonification, average 48.2, 59.4 and 62.1% of double-supercoiled DNA (dsDNA) were preserved, respectively. When medium of pDNA was 0.9% NaCl (pH 7.0), 0.1M NaHCO(3) (pH 8.0) or phosphate buffer (pH 8.0), average 53.1, 69.3 and 56.9% of dsDNA remained after sonification, respectively. Poly(aminopoly(ethylene glycol)cyanoacrylate-co-hexadecyl cyanoacrylate) (poly(H(2)NPEGCA-co-HDCA)) showed a slight influence on pDNA in 0.1M NaHCO(3) (pH 8.0) when its concentration increased from 0.5 to 4% (w/v). TF-PEG-nanoparticles loading pDNA were spherical in shape with size under 200nm and entrapment efficiency 35-50%. 0.1M NaHCO(3) with 3% PVA (w/v) could largely reduce the damage of pDNA during microencapsulation. TF-PEG-nanoparticles bore 1-3% of the total PEG chains conjugated to TF molecules, and exhibited the burst effect with over 30% drug release within 1 day. After the first phase, pDNA release profiles displayed a sustained release. The amount of cumulated pDNA release over 7 days was: 86.3, 81.5 and 74.4% for 1, 2 and 4% polymer nanoparticles, respectively. The degree of target K562 cell binding of TF-PEG-nanoparticles was greater than that of non-targeted PEG-nanoparticles at 4 degrees C. The presence of free TF decreased significantly the degree of cell binding of TF-PEG-nanoparticles, which revealed that the binding of TF-PEG-nanoparticles to K562 cells was indeed receptor specific. These results suggested that TF-PEG-nanoparticles were useful for delivery of pDNA to target cells.     

Physicochemical properties of a nonpeptide cyclic urea HIV protease inhibitor (DMP 323)

DMP 323 ([4R-(4α, 5α, 6β, 7β)]-hexahydro-5,6-bis(hydroxy)-1,3-bis ([(4-hydroxymethyl)phenyl]methyl)-4,7-bis(phenylmethyl)-2H-1,3-diazepin-2-one), a potent inhibitor of HIV protease and HIV replication, is a white irregular-shaped nonhygroscopic crystalline material. Differential scanning calorimetry revealed a single melt peak at 195.7°C. DMP 323 was practically insoluble in water at 10 µg/ml (pH 8.1) at 25°C. The aqueous solubility was unaffected by changes in pH. The logarithm of the solubility of DMP 323 is a linear function of the percentage of water miscible cosolvents. The highest solubility values of DMP 323 were 272 mg/ml in 95% (v/v) ethanol in water, 160 mg/ml in propylene glycol, 144 mg/ml in polyethylene glycol 400, 65.5 mg/ml in 70% (w/w) polyethylene glycol 1450 in water, 64.2 mg/ml in polyoxyethylene sorbitan monooleate, and 1.61 mg/ml in glycerin. DMP 323 was stable as a function of pH with no loss observed at pH 3, 5, 7, 9 and 12.7 in aqueous buffers containing 5% (v/v) methanol after eight weeks at 40°C. In polyethylene glycol 400 solutions, the degradation of DMP 323 was approximated with apparent first order kinetics at elevated temperatures. Butylated hydroxytoluene and butylated hydroxyanisole were effective antioxidants in reducing the degradation in polyethylene glycol 400 solutions while citric acid afforded no protection from the degradation. Argon flushing was effective at reducing the oxidative degradation in polyethylene glycol 400 solutions stored at room temperature. Consistent with the oxidative degradation, DMP 323 degraded to the mono- and dibenzaldehyde, the monobenzoic acid, and the monobenzaldehyde monobenzoic acid derivatives.     

Development and validation of an ultra performance liquid chromatography method for venlafaxine hydrochloride in bulk and capsule dosage form

A simple, specific, accurate, and precise ultra performance liquid chromatographic method was developed and validated for the estimation of venlafaxine hydrochloride in tablet dosage forms. A acquity TM BEH column having C18, 100×2.1 mm i.d. in isocratic mode, with mobile phase containing dipotassium hydrogen phosphate: Acetonitrile (30:70 v/v; pH 7.00 with dilute o-phosphoric acid) was used. The flow rate was 0.75 ml/min and effluents were monitored at 227 nm. The retention time of venlafaxine hydrochloride was 0.548 min. The method was validated for specificity, linearity, accuracy, precision, limit of quantification, limit of detection, robustness and solution stability. Limit of detection and limit of quantification for estimation of venlafaxine hydrochloride were found to be 6.11 μg/ml and 20.33 μg/ml, respectively. Recoveries of venlafaxine hydrochloride in tablet formulations were found to be in the range of 99.3-99.5%. Proposed method was successfully applied for the quantitative determination of venlafaxine hydrochloride in tablet dosage forms.     

Stability of irinotecan hydrochloride in aqueous solutions.

The stability of irinotecan after reconstitution in several vehicles for i.v. infusion was studied. Irinotecan hydrochloride injection was diluted in phosphate buffer solution (pH 4.0, 6.0, and 7.4), 5% dextrose injection, and 0.9% sodium chloride injection to a final concentration of 20 micrograms/mL. The solutions were stored at 25, 37, and 50 degrees C and assayed at intervals up to 24 hours by high-performance liquid chromatography for the concentration of the lactone form of irinotecan remaining. The effect of temperature and pH on the extent and rate of degradation of irinotecan was determined. The hydrolysis of irinotecan to its carboxylate form was reversible. The rate and extent of hydrolysis increased with increasing pH. The use of a weakly acidic vehicle, such as 5% dextrose injection, for reconstitution of irinotecan may maintain the drug's stability prior to administration.     

Transdermal Delivery of Isoproterenol HC1: An Investigation of Stability,Solubility, Partition Coefficient,and Vehicle Effects

Effects of solubility, partition coefficient, and selected adjuvants (propylene glycol and Azone) on percutaneous penetration of isoproterenol HC1 have been investigated using human cadaver skin. Isoproterenol was found to be stable (<1% decomposition) for 24 hr at 22 ± 0.5°C in the pH range 1 to 7 in the following solvents: water, normal saline, propylene glycol and a series of propylene glycol–water mixtures (10, 20, 40, and 60%; v/v); however, decomposition was significant beyond pH 8. In normal saline, the rate of decomposition increased significantly with an increase in temperature to 37°C. The solubility of isoproterenol HC1 decreased and its skin/vehicle partition coefficient increased with increasing proportions of propylene glycol in the vehicle, while the product of the solubility and partition coefficient appeared to plateau at 20% propylene glycol in water. Optimal penetration enhancing effects of Azone were seen when incorporated at a concentration of 1% (v/v) in the 20% (v/v) propylene glycol–water blend and, more significantly, when skin was pretreated with pure Azone for 60 min prior to application of the drug formulation.     

Simultaneous RP-HPLC Estimation of Cefpodoxime Proxetil and Clavulanic Acid in Tablets

A new, simple, precise, rapid and accurate RP-HPLC method has been developed for the simultaneous estimation of cefpodoxime proxetil and clavulanic acid from pharmaceutical dosage forms. The method was carried out on a Zorbax Eclipse XDB 5 μ C 18 (150×4.6 mm) column with a mobile phase consisting of acetonitrile:50 mM potassium dihydrogen phosphate buffer (pH 3.0, 70:30 v/v) at a flow rate of 1.0 ml/min. Detection was carried out at 228 nm. Aspirin was used as an internal standard. The retention time of clavulanic acid, cefpodoxime proxetil and aspirin was 4.43, 6.44 and 5.6 min, respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantification and solution stability. The proposed method can be used for the estimation of these drugs in combined dosage forms.     

Antitumor activities of conjugates of mitomycin C with estradiol benzoate and estradiol via glutaric acid in suspension dosage form

Conjugates of mitomycin C (MMC) with estradiol bezoate and estradiol via glutaric acid (EB-glu-MMC and E-glu-MMC, respectively) were examined for their antitumor activities against P388 leukemia and sarcoma 180. EB-glu-MMC and E-glu-MMC were suspended in 10% (v/v) propylene glycol in saline and administered intraperitoneally to mice bearing P388 leukemia intraperitoneally or to mice bearing sarcoma 180 subcutaneously. The antitumor effect against P388 leukemia was greater in the order MMC>E-glu-MMC>EB-glu-MMC, and only the former two compounds significantly increased life span. On the other hand, EB-glu-MMC and E-glu-MMC showed suppression of sarcoma 180 growth at higher doses close to or better than MMC. In the mixture of 1/15 M phosphate buffer (pH 7.4, ionic strength (mu) adjusted to 0.3 with NaCl)-propylene glycol (9:1, v/v) at 37 degrees C, MMC was released much more slowly from EB-glu-MMC suspension than from E-glu-MMC suspension. With regard to chemotherapy against sarcoma 180, both conjugates were considered to supply MMC slowly but effectively at higher doses.