Stability of curcumin in buffer solutions and characterization of its degradation products

The degradation kinetics of curcumin under various pH conditions and the stability of curcumin in physiological matrices were investigated. When curcumin was incubated in 0.1 M phosphate buffer and serum-free medium, pH 7.2 at 37°C, about 90% decomposed within 30 min. A series of pH conditions ranging from 3 to 10 were tested and the result showed that decomposition was pH-dependent and occurred faster at neutral-basic conditions. It is more stable in cell culture medium containing 10% fetal calf serum and in human blood; less than 20% of curcumin decomposed within 1 h, and after incubation for 8 h, about 50% of curcumin is still remained. Trans-6-(4′-hydroxy-3′-methoxyphenyl)-2,4-dioxo-5-hexenal was predicted as major degradation product and vanillin, ferulic acid, feruloyl methane were identified as minor degradation products. The amount of vanillin increased with incubation time.     

Stability of the Thrombolytic Protein Fibrolase: Effect of Temperature and pH on Activity and Conformation

The effect of temperature and pH on the activity and conformation of the thrombolytic protein fibrolase was examined. Fibrolase maintained proteolytic activity over 10 days at room temperature (22°C). At 37°C, greater than 50% of the proteolytic activity was lost within 2 days and no activity remained after 10 days. Circular dichroism (CD) spectra at elevated temperatures showed that alphahelical structure was lost in a cooperative transition (T _m of 50°C at pH 8). Structural changes were detected by NMR prior to unfolding which were not observable by CD, and the T _m determined by NMR was 46°C at pD 8. The effect of pH on the proteolytic activity and structure of fibrolase was examined over the pH range from 1 to 10. Activity was maintained at neutral to alkaline pH values from pH 6.5 to pH 10.0 but decreased substantially in acidic media. While CD spectra indicated little variation in secondary structure over the pH range 5 to 9, significant differences were noted at pH 2 to 3. The melting temperature of fibrolase decreased to 43°C at pH 5. Protein concentrations determined over the pH range 1 to 10 showed an apparent solubility minimum at pH 5.0, which did not correspond to the isoelectric point of 6.5. Explanations for these observations are proposed.     

Study on the compatibility of cefotaxime with tinidazole in glucose injection

An efficient HPLC method for the compatibility study of cefotaxime with tinidazole in glucose injection is described, which has been developed for the simultaneous determination of cefotaxime and tinidazole in glucose injection. The appearance and pH value of the mixed solution were investigated and the concentrations of cefotaxime and tinidazole were determined by RP-HPLC with an Agilent ZORBAX Eclipse XDB-C₈ column, gradient elution and dual wavelength detection on diode-array-detector (DAD) at room temperature (20 °C) within 24 h. It was found that the resulting appearance and pH value of the mixed solution showed slight changes, on the other hand, the quantity of cefotaxime decreased significantly. The results show that the mixed solution of cefotaxime with tinidazole in glucose injection must be used within 8 h in clinical due to the possible degradation of cefotaxime in tinidazole glucose injection. This study provides a convenient method for rational use of compatible drugs in clinical practice.     

Simultaneous determination of triamcinolone acetonide and oxymetazoline hydrochloride in nasal spray formulations by HPLC

A high-performance liquid chromatography (HPLC) method with UV detection at 232 nm was developed and validated for the simultaneous determination of triamcinolone acetonide (TAA) and oxymetazoline hydrochloride (OXY) in nasal spray formulations. The chromatographic system consisted of a μBondapak™ CN column (150 mm × 3.9 mm), 5 μm particle size with a mobile phase composition of acetonitrile:ammonium acetate (pH 5.0, 20 mM) (10:90, v/v) at a flow rate of 1.0 mL/min. Calibration curves were linear for both TAA and OXY in the concentration range of 2.5–25.0 μg/mL. The limit of detection and quantitation were 0.29 and 0.88 μg/mL for OXY and 0.24 and 0.73 μg/mL for TAA. The described method was further applied to the analysis and stability studies of two nasal spray formulations I and II prepared from TAA and OXY commercial nasal spray products. The stability of OXY and TAA in the commercial products and the nasal formulations I and II were analyzed after 30 days at room temperature and 30 days at 40 °C/60% relative humidity. The results of the stability study showed that OXY and TAA in the commercial nasal spray products and the nasal formulations I and II were stable at 20–25 °C (room temperature) but TAA was unstable at 40 °C/60% relative humidity. TAA exhibited more than 10% loss at 14 days in both the nasal formulations and in the commercial products. OXY showed increased degradation at 40 °C/60% relative humidity but <10%.     

Delivery of didanosine from enteric-coated,sustained-release bioadhesive formulation

The aim of our study is to assess the release characteristics, in vitro permeation, and stability of an enteric-coated, bioadhesive, sustained-release formulation of didanosine (ddI). Enteric-coated tablets of ddI, containing Polyox® WSRN-303 and Methocel K4M, were prepared using hydroxypropylmethylcellulose phthalate (HPMCP 5.5). The enteric-coated formulation was resistant to dissolution in 0.1 N HCl solution but dissolved within 10 min ( ±2 min) in pH 7.4 phosphate buffered saline. The release profiles were linear with square root time. Stability studies indicate that the formulations were stable at 4°C, room temperature, and 40°C upon storage for 6 months. Polyox® WSRN-303 tablets exhibited a higher ddI permeation ratio across live intestinal tissue compared with conventional tablets. Enteric-coated, sustained-release, bioadhesive tablets deliver ddI in small doses and at the same time prevent acid-induced degradation and hence hold a potential to improve ddI's oral bioavailability.     

Stability of thioTEPA and its metabolites, TEPA, monochloroTEPA and thioTEPA-mercapturate, in plasma and urine

The degradation of N,N′,N′′-triethylenethiophosphoramide (thioTEPA) and its metabolites N,N′,N′′-triethylenephosphoramide (TEPA), N,N′-diethylene,N′′-2-chloroethylphosphoramide (monochloroTEPA) and thioTEPA-mercapturate in plasma and urine has been investigated. ThioTEPA, TEPA and monochloroTEPA were analyzed using a gas chromatographic (GC) system with selective nitrogen/phosphorous detection; thioTEPA-mercapturate was analyzed on a liquid chromatography-mass spectrometric (LC-MS) system. The influences of pH and temperature on the stability of thioTEPA and its metabolites were studied. An increase in degradation rate was observed with decreasing pH as measured for all studied metabolites. In urine the rate of degradation at 37°C was approximately 2.5±1 times higher than at 22°C. At 37°C thioTEPA and TEPA were more stable in plasma than in urine, with half lives ranging from 9–20 h for urine and 13–34 h for plasma at pH 6. Mono- and dichloro derivatives of thioTEPA were formed in urine and the monochloro derivative was found in plasma. Degradation of TEPA in plasma and urine resulted in the formation of monochloroTEPA. During the degradation of TEPA in plasma also the methoxy derivative of TEPA was formed as a consequence of the applied procedure. The monochloro derivative of thioTEPA-mercapturate was formed in urine, whereas for monochloroTEPA no degradation products could be detected.     

Intraliposomal chemical activation patterns of liposomal cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II) (L-NDDP)-a potential antitumour agent

L-NDDP is a liposome-entrapped platinum compound currently in phase 2 clinical trials that has been shown to undergo intraliposomal activation. The degradation/activation kinetics of liposome entrapped cis-bis-neodecanoatotrans-R,R-1,2-diamminocyclohexane platinum (II) [L-NDDP] at different conditions of pH, and temperature is presented. Liposomes were reconstituted in a solution of 0.9% sodium chloride (NaCl) in water (pH 5) at room temperature (formulation conditions currently used in the ongoing clinical trials). In the temperature experiments, L-NDDP 0.9% sodium chloride liposomes were incubated in a water-bath at 40, 60, and 80 C. In the pH experiments, these solutions were compared to water, phosphate with and without chloride ion present, phosphate buffer without chloride ion at pH 3.1, 5.0, and 7.4, and glycine buffer with and without chloride ion. In 0.9% sodium chloride at room temperature, the chemical degradation/activation of liposome-bound NDDP was biphasic, with most of the degradation (approximately 45% conversion) occurring during the first hour after formation of the liposome suspension. NDDP degradation was pH dependent: when using pH 3 phosphate buffer as a reconstituting solution, liposome-bound NDDP degraded rapidly, whereas in pH 7.4 phosphate buffer it was stable for &gt; 72h. NDDP degradation was also temperature-dependent, the 50% point decreasing from 12h at 25C to 9.5h at 40C, 3.8h at 60C and 0.3h at 80C when using 0.9% NaCl in water as a reconstituting solution. Using glycine buffer solution with and without NaCl at room temperature, no L-NDDP degradation over a 72h period was observed at 25C; however, at 40C, only 68% NDDP remained intact at 72h. Atomic absorption spectrophotometry (AAS) analysis of the eluting fractions after injection of L-NDDP samples reconstituted in chloridecontaining and non chloride-containing solutions clearly indicated that the formation of DACH-Pt-Cl₂ was only observed when chloride-containing solutions were used and was first detected at 3h when using 0.9% NaCl in water as a reconstituting solution. These results indicate that pH and temperature, and not the presence of chloride ion, are the main factors leading to the activation of NDDP. Since 45%of NDDP is already degraded at 1h in the same conditions, it is concluded that (1) the first active intermediates of L-NDDP formed within the liposomes are the DACH-Pt chloro-aquo and diaquo intermediates, and (2) the in vivo, antitumour activity of L-NDDP is most likely mediated by direct intracellular delivery of the active species.     

Intraliposomal chemical activation patterns of liposomal cis-bis-neodecanoato-trans-R,R-1,2-diaminocyclohexane platinum (II) (L-NDDP)-a potential antitumour agent

L-NDDP is a liposome-entrapped platinum compound currently in phase 2 clinical trials that has been shown to undergo intraliposomal activation. The degradation/activation kinetics of liposome entrapped cis-bis-neodecanoato-trans-R,R-1,2-diamminocyclohexane platinum (II) [L-NDDP] at different conditions of pH, and temperature is presented. Liposomes were reconstituted in a solution of 0.9% sodium chloride (NaCl) in water (pH 5) at room temperature (formulation conditions currently used in the ongoing clinical trials). In the temperature experiments, L-NDDP 0.9% sodium chloride liposomes were incubated in a water-bath at 40, 60, and 80 degrees C. In the pH experiments, these solutions were compared to water, phosphate with and without chloride ion present, phosphate buffer without chloride ion at pH 3.1, 5.0, and 7.4, and glycine buffer with and without chloride ion. In 0.9% sodium chloride at room temperature, the chemical degradation/activation of liposome-bound NDDP was biphasic, with most of the degradation (approximately 45% conversion) occurring during the first hour after formation of the liposome suspension. NDDP degradation was pH dependent: when using pH 3 phosphate buffer as a reconstituting solution, liposome-bound NDDP degraded rapidly, whereas in pH 7.4 phosphate buffer it was stable for > 72 h. NDDP degradation was also temperature-dependent, the 50% point decreasing from 12 h at 25 degrees C to 9.5 h at 40 degrees C, 3.8 h at 60 degrees C, and 0.3 h at 80 degrees C when using 0.9% NaCl in water as a reconstituting solution. Using glycine buffer solution with and without NaCl at room temperature, no NDDP degradation over a 72 h period was observed at 25 degrees C; however, at 40 degrees C, only 68% NDDP remained intact at 72 h. Atomic absorption spectrophotometry (AAS) analysis of the eluting fractions after injection of L-NDDP samples reconstituted in chloride-containing and non chloride-containing solutions clearly indicated that the formation of DACH-Pt-Cl2 was only observed when chloride-containing solutions were used and was first detected at 3 h when using 0.9% NaCl in water as a reconstituting solution. These results indicate that pH and temperature, and not the presence of chloride ion, are the main factors leading to the activation of NDDP. Since 45% of NDDP is already degraded at 1 h in the same conditions, it is concluded that (1) the first active intermediates of L-NDDP formed within the liposomes are the DACH-Pt chloro-aquo and diaquo intermediates, and (2) the in vivo, antitumour activity of L-NDDP is most likely mediated by direct intracellular delivery of the active species.     

Stability of 5-aminolevulinic acid in aqueous solution

The chemical stability of 5-aminolevulinic acid (ALA) was studied in aqueous solution as a function of concentration, pH, temperature and in the presence of ethylenediaminetetraacetic acid (EDTA). The degradation of ALA was followed by reversed-phase liquid chromatography using a pH where ALA is protonated (pK_a1=3.90; pK_a2=8.05, as determined potentiometrically). ALA was degraded by a reaction following second order kinetics. Stock solutions of 1% (60 mM) ALA were incubated at 50°C. At pH 2.35, ALA was stable during the whole incubation period (37 days). The half-lives for the second-order decomposition of 1% ALA at pH 4.81 and 7.42 were 257 and 3.0 h, respectively. The degradation rate increased about 1.5 times with each 10°C rise in temperature at pH 7.53 within the range studied (37–85°C). The energy of activation, E_a, for the second-order decomposition of ALA was 43.7 kJ mol⁻¹. EDTA did not influence the degradation of ALA when a mixture of 1% ALA and 1% EDTA was incubated at pH 7.42.     

Camptothecin-catalyzed phospholipid hydrolysis in liposomes

Hydrolysis of phospholipid (PL) within camptothecin (CPT)-containing liposomes was studied systematically, after elevated lyso-phosphatidylcholine (LPC)-concentrations in pH 5, CPT-containing liposomes (22.1+/-0.9 mol%) relative to control-liposomes (7.3+/-0.5 mol%) occasionally had been observed after four months storage in fridge. Liposomes were prepared by dispersing freeze-dried PL/CPT mixtures in 25 mM phosphate buffered saline (PBS) of varying pH (5.0-7.8) and CPT concentrations (0, 3 and 6 mM). PL-hydrolysis was monitored by HPTLC, quantifying LPC. In an accelerated stability study (60 degrees C), a catalytic effect of CPT on PL-hydrolysis was observed after 40 h, but not up to 30 h of incubation. The pH profile of the hydrolysis indicated a stability optimum at pH 6.0 for the liposomes independent of CPT. The equilibrium point between the more active lactone- and the carboxylate-form of CPT was found to be pH 6.8. As a compromise, pH 6.0 was chosen, assuring >85% CPT to be present in the lactone form. At this pH, both control- and CPT-liposomes showed only minor hydrolysis after autoclaving (121 degrees C, 15 min). Storage at room temperature and in fridge (2 months), as well as accelerated ageing (70 degrees C, 25 h), gave a significant elevation of LPC content in CPT-liposomes relative to control-liposomes. This study demonstrates a catalytic effect of CPT on PL-hydrolysis, the onset of which seems to require a certain threshold level of hydrolytic degradation.     

Stability and degradation profiles of Spantide II in aqueous solutions.

Spantide II is an 11 amino acid peptide that has been shown to be a potential anti-inflammatory agent. The stability and degradation profiles of Spantide II in aqueous solutions were evaluated with the long-term objective of developing topical formulations of this compound for various skin disorders. The stability profile of Spantide II at various temperature and pH conditions was monitored by high performance liquid chromatography (HPLC) and the resulting degradation products were identified by liquid chromatography-mass spectroscopy (LC-MS). Forced degradation of Spantide II was performed at extreme acidic (pH <2.0) and alkaline (pH >10.0) conditions and by addition of hydrogen peroxide (oxidizing agent). The degradation pattern of Spantide II followed pseudo first-order kinetics. The shelf life (T90%) of Spantide II in aqueous ethanol (50%) was determined to be 230 days at 25 degrees C. Spantide II was susceptible to degradation at pH <2 and pH >5 and showed maximum stability at pH 3-5. The stability under various pH conditions indicates that Spantide II was most stable at pH 3.0 with a half-life of 95 days at 60 degrees C. Spantide II degradation was attributed to hydrolysis of peptide bonds [Pro2-(pyridyl)Ala3, (nicotinoyl)Lys1-Pro2, Pro4-PheCl2(5), Trp7-Phe8, Phe8-Trp9, Nle11-NH2), racemization of the peptide fragments that resulted from hydrolysis, cleavage and formation of (nicotinoyl)Lys1-Pro2 diketopiperazine. In the presence of an oxidizing agent, Pro(2,4) residues degraded by ring opening to form glutamyl-semialdehyde and by bond cleavage at Pro4 to form 2-pyrrolidone, while Phe(5,8) degraded to form 2-hydroxyphenylalanine. Spantide II was found to be stable in aqueous medium with T90% of 230 days. The major degradation pathways of Spantide II were identified as hydrolysis, racemization, cleavage and formation of diketopiperazine.     

The kinetics and mechanism of the hydrolysis of cyclopentolate hydrochloride in alkaline solutions

Cyclopentolate hydrochloride (Cy · HC1) is an ester of a substituted benzeneacetic acid, having N,N-dimethyl-aminoethanol as the alcohol moiety. A reversed-phase HPLC assay was employed to investigate the kinetics of degradation of Cy · HCI. The influence of pH, buffers, and temperature was studied in alkaline solutions. The degradation follows (pseudo) first-order kinetics at 50°C. Results indicate that it degrades very rapidly at higher pH values. Phenylacetic acid and a-(1-hydroxycyclopentyl)benzeneacetic acid were isolated and identified as the degradation products. The reaction mechanism appears to follow a parallel scheme where phenylacetic acid and a-(1-hydroxycyclopentyl)benzeneacetic acid are formed simultaneously. It is proposed that -(1-hydroxycyclopentyl)benzeneacetic acid is formed by normal ester hydrolysis. Phenylacetic acid is formed via a six-membered transition state and its formation requires the assistance of the hydroxyl group from the adjacent cyclopentanol moiety.     

Effects of immunological and hematological parameter in mice exposed to mixture of volatile organic compounds

Exposure to some kinds of volatile organic compounds (VOCs) leads to immune system disorders, liver and kidney damage, hematological change. However, there is little information about the effect of VOCs mixture on immune system and hematological parameter. In this study, 50 Kunming male mice were exposed in five similar chambers, 0 (control) and four different doses of VOCs mixture (G1–4) for consecutively 10 days at 2?h/day. The concentrations of VOCs mixture were as follows: formaldehyde, benzene, toluene and xylene 1.0?+ 1.1?+ 2.0?+ 2.0, 3.0?+ 3.3?+ 6.0?+ 6.0, 5.0?+ 5.5?+ 10.0?+ 10.0 and 10.0?+ 11.0?+ 20.0?+ 20.0?mg/m³, respectively, which corresponded to 10, 30, 50 and 100 times of indoor air quality standard in china. One day following VOCs exposure, spleen T lymphocyte subpopulation, serum biochemical markers and peripheral blood cells in mice were analyzed, respectively. VOCs exposure decreased significantly erythrocyte count (RBC), platelet (PLT) in peripheral blood in mice. While aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), alkaline phosphatase (ALP) and creatinine (CREA) in serum increased significantly in G4 mice versus controls. Flow cytometry analysis showed that the number of splenic lymphocyte subpopulation cells decreased significantly in G2, 3 and 4 mice in comparison with normal Kunming mice. These results indicate inhalation of VOCs mixture affects CD4/8 subpopulations, liver, kidney function and some hematological parameters in mice.     

A preformulation study on the kinetics of HI-6 in concentrated solution

The degradation kinetics of HI-6 have been investigated at various temperatures and at different pHs at a concentration of 200 mg/ml. Both aqueous and other hydrophilic solvents (glycols and glycerol-water mixtures) have been used. The degradation of HI-6 follows pseudo-first-order kinetics with respect to HI-6. The observed rate seems to depend on a hydroxyl ion-catalyzed reaction (k_OH) and an un/water catalyzed reaction (k₀) which show influence at pH below 3. The pH profile shows a positive slope less than one, which seems to depend on an error in the determination of the rate constants at higher pH. k_OH was determined to be 1 · 10⁹ andk₀ to be 0 · 011 h⁻¹ at 60° C. The observed rate seems to be independent of the dielectric constant of the solvent. The activation energy k₀ has been determined to be 82.0 kJ mol⁻¹. Based upon these data the predicted shelf life (t_90%) at pH 0 will not be long than 13 days at 25 ° C and 9 months at 0°C. Thus, the systems studied seem to be unsuitable to formulate a stable intramuscular formulation of HI-6.     

Stability of Diluted Adenosine Solutions in Polyolefin Infusion Bags

Background:

Intravenous or intracoronary adenosine is used in the cardiac catherization lab to achieve maximal coronary blood flow and determine fractional flow reserve.

Objective:

To determine the stability of adenosine 10 and 50 µg/mL in either 0.9% sodium chloride injection or 5% dextrose injection in polyolefin infusion bags stored at 2 temperatures, refrigeration (2°C-8°C) or controlled room temperature (20°C-25°C).

Methods:

Adenosine 10 µg/mL and 50 µg/mL solutions were prepared in 50 mL polyolefin infusion bags containing 0.9% sodium chloride injection or 5% dextrose injection and stored at controlled room temperature or under refrigeration. Each combination of concentration, diluent, and storage was prepared in triplicate. Samples were assayed using stability-indicating, reversed-phase high-performance liquid chromatography immediately at time 0 and at 24 hours, 48 hours, 7 days, and 14 days. Stability was defined as retaining 90% to 110% of the initial adenosine concentration. The samples were also visually inspected against a light background for clarity, color, and the presence of particulate matter.

Results:

After 14 days, all samples retained 99% to 101% of the initial adenosine concentration. No considerable change in pH or visual appearance was noted. The stability data indicated no significant loss of drug due to chemical degradation or physical interactions during storage.

Conclusion:

Adenosine solutions of 10 and 50 µg/mL were stable for at least 14 days in 50 mL polyolefin infusion bags of 0.9% sodium chloride injection or 5% dextrose injection stored at controlled room temperature and refrigerated conditions.     

Stability of Azacitidine in Sterile Water for Injection

Background:

The product monograph for azacitidine states that once reconstituted, the drug may be held for only 30 min at room temperature or 8 h at 4°C. Standard doses result in wastage of a portion of each vial, and the cost of this wastage is significant, adding about $156 000 to annual drug expenditures at the authors’ institution.

Objective:

To evaluate the stability of azacitidine after reconstitution.

Methods:

Vials of azacitidine were reconstituted with sterile water for injection. At the time of reconstitution, the temperature of the diluent was 4°C for samples to be stored at 4°C or −20°C and room temperature for samples to be stored at 23°C. Solutions of azacitidine (10 or 25 mg/mL) were stored in polypropylene syringes and glass vials at room temperature (23°C), 4°C, or −20°C. The concentration of azacitidine was determined by a validated, stability-indicating liquid chromatographic method in serial samples over 9.6 h at room temperature, over 4 days at 4°C, and over 23 days at −20°C. The recommended expiry date was determined on the basis of time to reach 90% of the initial concentration according to the fastest observed degradation rates (i.e., lower limit of 95% confidence interval).

Results:

Azacitidine degradation was very sensitive to temperature but not storage container (glass vial or polypropylene syringe). Reconstitution with cold sterile water reduced degradation. At 23°C, 15% of the initial concentration was lost after 9.6 h; at 4°C, 32% was lost after 4 days; and at −20°C, less than 5% was lost after 23 days.

Conclusions:

More than 90% of the initial azacitidine concentration will be retained, with 97.5% confidence, if, during the life of the product, storage at 23°C does not exceed 2 h, storage at 4°C does not exceed 8 h, and storage at −20°C does not exceed 4 days. These expiry dates could substantially reduce wastage and cost where the time between doses does not exceed 4 days.     

SERUM CONCENTRATIONS OF DIGOXIN ENTRAPPED IN LIPOSOMES AFTER INTRAVENOUS ADMINISTRATION IN DOGS

1. Digoxin was associated into phosphotidylcholine liposomes at concentrations of 28–33 mol% in Hank's Buffer, pH 7.4 at 28°C. 2. Digoxin-liposomes (digoxin concentration 0.022 mg/kg per dog per day) administered intravenously in five adult male dogs attained therapeutic serum concentrations (0.7–3.0 ng/ml) beginning with day 1 of administration. 3. Digoxin serum concentrations obtained by intravenous digoxin-liposomes compared favorably with normal oral digoxin administration (0.022 mg/kg per dog per day) in all 5 dogs monitoring serum digoxin levels for 7 days showed no significant (P<0.05) differences in mean serum digoxin concentrations ± s.e.m. on 6 of 7 days of treatments.     

Stability of stored methacholine solutions: study of hydrolysis kinetic by IP-LC

Methacholine chloride is a powerful cholinergic bronchoconstrictor agent used during bronchial airway hyper-responsiveness diagnosis. Methacholine is susceptible to hydrolysis in aqueous solutions in acetic acid and β-methylcholine. In the present work, kinetics of hydrolysis with different solvents (water and phosphate-buffered saline (PBS) pH 7.4) at different temperatures have been studied using a newly developed high-performance liquid chromatography. At 4°C, kinetic determination of hydrolysis in methacholine chloride solutions (50 mg/ml) shows no hydrolysis in either aqueous or phosphate-buffered solutions over a 40-day period. At 30°C, concentration of unbuffered methacholine chloride solutions remained unchanged, but buffered methacholine chloride solutions have degradation up to 5.5% over a 40-day period. At 40°C, concentration of unbuffered methacholine chloride has degradation up to 5% and buffered methacholine chloride solutions have degradation up to 10% over a 40-day period. Methacholine chloride solutions are susceptibly to be used in hospital pharmacy at different concentrations. We have studied pH and osmolality for methacholine solutions prepared with different diluents potentially used in hospital pharmacies, i.e. deionized water, 0.9% NaCl and PBS pH 7.4. We have demonstrated that methacholine solutions prepared with deionized water at 50 mg/ml and diluted with PBS pH 7.4 from 5 to 40 mg/ml are isoosmotic and potentially available for inhalation tests to measure non-specific bronchial hyper-responsiveness.     

Shelf lives of aseptically prepared medicines--stability of netilmicin injection in polypropylene syringes

There is no published information on the stability of netilmicin solutions in prefilled syringes. The purpose of this study was to evaluate the stability of netilmicin in polypropylene syringes and to determine the optimum validated shelf life so that they may be prepared in bulk in appropriately licensed facilities.

The syringes containing netilmicin 10 or 100 mg/ml were stored at 7 °C, room temperature in the light (RTL) and 25 °C/60% relative humidity for up to 300 days.

Netilmicin concentration was determined by reversed phase high performance liquid chromatography (RP-HPLC) of the isoindole derivative formed with o-phthalaldehyde (OPA). The shelf lives were calculated using the maximum rate method applied to the netilmicin analytical data. At 7 °C 10 and 100 mg/ml solutions were stable for 90 days falling to 30 days at 25 °C and 60% RH. At RTL the 10 mg/ml solution was stable for 9 days.     

Stability of Ertapenem 100 mg/mL in Manufacturer’s Glass Vials or Syringes at 4°C and 23°C

Background:

Prophylactic administration of ertapenem as a single 1-g IV dose has been shown to reduce sepsis after prostate biopsy.

Objective:

To evaluate the stability of ertapenem after reconstitution with 0.9% sodium chloride to a final concentration of 100 mg/mL and storage in the manufacturer’s original glass vials or polypropylene syringes.

Methods:

On study day 0, 100 mg/mL solutions of ertapenem were retained in the manufacturer’s glass vials or packaged in polypropylene syringes and stored at 4°C or 23°C without protection from fluorescent room light. Samples were assayed periodically over 18 days using a validated, stability-indicating liquid chromatographic method with ultra-violet detection. A beyond-use date was determined as the time for the concentration to decline to 90% of the initial (day 0) concentration, based on the fastest degradation rate, with 95% confidence.

Results:

Reconstituted solutions stored in the manufacturer’s glass vials or polypropylene syringes exhibited a first-order degradation rate, such that 10% of the initial concentration was lost in the first 2.5 days when stored at 4°C or within the first 6.75 h when stored at room temperature (23°C). Analysis of variance showed differences in the percentage remaining due to temperature (p < 0.001) and study day (p < 0.001) but not type of container (p = 0.98). When a 95% CI for the degradation rate was calculated and used to determine a beyond-use date, it was established that more than 90% of the initial concentration would remain for 2.35 days at 4°C and for 0.23 day (about 5 h, 30 min) at room temperature.

Conclusions:

A 100 mg/mL ertapenem solution stored in the manufacturer’s glass vial or a polypropylene syringe will retain more than 90.5% of the initial concentration when stored for 48 h at 4°C and for an additional 1 h at 23°C.