Quantitative aspects of the degradation of mitomycin C in alkaline solution

Physicochemical stability of ready-to-administer mitomycin C solutions for intravesical instillation

OBJECTIVE

The aim of the study was to investigate the physicochemical stability of mitomycin-containing medicinal products for bladder instillation, formulated with urea as excipient (mito-medac®, Mitomycin medac). For comparison, the stability of reconstituted Urocin® and Mitem® bladder instillation was studied.

METHODS

Mitomycin-containing medicinal products were either reconstituted with the prepackaged 0.9% NaCl solution, nominal volume 20 mL (mito-medac®, Mitem®, Urocin®) or with 20 mL water for injection (Mitomycin medac, Mitem®, Urocin®) to a nominal concentration of 1 mg/mL and stored at room temperature (20-25°C). Samples were taken immediately after reconstitution and after 24 hours. Physicochemical stability was determined by reverse-phase high performance liquid chromatography with photodiode array detection, measurement of pH and osmolarity, and inspection for visible particles or colour changes.

RESULTS

The initial pH values of the test solutions reconstituted with prepackaged 0.9% NaCl (5.2-5.6) were significantly lower than those reconstituted with water for injection (6.6-7.4). Solutions reconstituted with 0.9% NaCl solutions rapidly degraded and concentrations fell below the 90% limit after 24 hours of storage. When reconstituted with water for injection, degradation was less rapid. Concentrations of Mitomycin medac and Urocin remained above the 90% limit after 24 hours.

CONCLUSIONS

The physicochemical stability of mitomycin 1 mg/mL bladder instillation prepared with prepackaged 0.9% NaCl in prefilled PVC bags is less than 24 hours at room temperature. Unfavourable pH values of the solvents cause rapid degradation of mitomycin. Mitomycin solutions reconstituted at the point of care should be administered immediately to avoid degradation and loss of efficacy. Urea added as excipient did not accelerate degradation.

Development and investigation of a novel device with gemcitabine for hyperthermic intravesical chemotherapy

PURPOSE

To evaluate the safety and efficacy of a novel hyperthermic intravesical chemotherapy (HIVEC) device in combination with gemcitabine.

MATERIALS AND METHODS

A pilot clinical trial was performed on patients with high-risk non-muscle invasive bladder cancer (NMIBC), who received HIVEC via the novel device (BR-PRG). Treatment regimen included eight weekly instillations of intravesical GEM (3 g in 150 mL normal saline [NS]) at a temperature of 45 °C for 60 min. Assessment of adverse events (AEs) was the primary objective of the trial. Disease recurrence and the thermal stability of GEM were also analyzed.

RESULTS

A total of 116 HIVEC treatments were delivered. Fifteen and eighteen patients were included in the effectiveness and safety analysis, respectively. Median follow-up was 12 months; five patients experienced a disease recurrence. One-year cumulative incidence of recurrence was 23.8% in EORTC intermediate risk group and 37.5% in high-risk group. Ten patients experienced at least one AE, with the most common being acute urinary tract infection, followed by urinary tract pain, and hematuria. Two patients experienced acute cystitis (grade 3 AE) and instillations were postponed until full recovery. Other AEs were minor, and no systemic toxicity was observed. The contents of GEM in solution of 0.9% NS or NS mixed with artificial urine were stable at 25 °C, 37 °C, 43 °C, 45 °C, 47 °C and 50 °C for 2 h.

CONCLUSION

GEM can be an ideal drug for use in HIVEC due to its good thermal stability. BR-PRG, combined with GEM was safe and effective in administering HIVEC.

Effects of Lidocaine on Mitomycin C Cytotoxicity

PURPOSE

Intra-Tenon or subconjunctival injection of a solution of mitomycin C (MMC) and 1% preservative-free lidocaine (as an anesthetic) has gained popularity for its use in trabeculectomy, a filtering surgery for glaucoma. To our knowledge, no studies have analyzed the impact of lidocaine on the cytotoxic effects of MMC in this setting. This study was conducted to evaluate in vitro fibroblast cytotoxicity to a solution of MMC (0.2 mg/ml) and 1% preservative-free lidocaine.

DESIGN

Experimental study.

PARTICIPANTS

Nonhuman subject research.

METHODS

Cultured human conjunctival fibroblasts were incubated in phosphate-buffered saline (PBS) (control), MMC (0.2 mg/ml), a mixture of 0.2 mg/ml MMC + 1% preservative-free lidocaine, or 1% preservative-free lidocaine. Samples were taken at 2, 5, 10, 30, and 60 minutes, and a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay with photoabsorbance testing was used to assess conjunctival cell viability.

MAIN OUTCOME MEASURE

Mean photoabsorbance.

RESULTS

Mean photoabsorbance across all time intervals was 0.680 for solutions incubated in PBS, 0.642 for MMC, 0.612 for MMC + 1% preservative-free lidocaine, and 0.605 for 1% preservative-free lidocaine. A 2-way analysis of variance analyzing solution, time, and solution-time interaction on photoabsorbance showed that PBS was least cytotoxic and an optimal control for this study. Tukey post hoc comparisons showed that MMC was more cytotoxic than PBS (P < 0.001). However, both MMC + 1% preservative-free lidocaine and 1% preservative-free lidocaine were more cytotoxic than MMC and PBS (P < 0.01 for all). No significant differences in cytotoxicity comparing lidocaine-containing solutions were observed.

CONCLUSIONS

In this in vitro study, we found an increase in cytotoxicity when MMC (0.2 mg/ml) was combined with 1% preservative-free lidocaine. We note that lidocaine did not inhibit MMC cytotoxicity and exhibited a significant cytotoxic effect on its own.

Coupling High-Performance Thin-Layer Chromatography with Bacterial Genotoxicity Bioreporters

We present an innovative technological platform for monitoring the direct genotoxicity of individual components in complex environmental samples, based on bioluminescent Escherichia coli genotoxicity bioreporters, sprayed onto the surface of a high-performance thin-layer chromatography (HPTLC) plate. These sensor strains harbor plasmid-borne fusions of selected gene promoters of the E. coli SOS DNA repair system to the Photorhabdus luminescens luxABCDE gene cassette, and mark by increased luminescence the presence of potentially DNA-damaging sample components separated on the plate. We demonstrate an "on plate" quantifiable dose-dependent response to several model genotoxicants (without metabolic activation). We further demonstrate the applicability of the system by identifying as genotoxic specific components of HPTLC-separated influent and effluent samples of wastewater treatment plants, thereby alleviating the need for a comprehensive chemical analysis of the sample.

Solubilization and Stability of Mitomycin C Solutions Prepared for Intravesical Administration

BACKGROUND

Mitomycin C (MMC) is an antitumor agent that is often administered intravesically to treat bladder cancer. Pharmacologically optimized studies have suggested varying methods to optimize delivery, with drug concentration and solution volume being the main drivers. However, these MMC concentrations (e.g. 2.0 mg/mL) supersede its solubility threshold, raising major concerns of inferior drug delivery.

OBJECTIVE

In this study, we seek to confirm that the pharmacologically optimized MMC concentrations are achievable in clinical practice through careful modifications of the solution preparation methods.

METHODS

MMC admixtures (1.0 and 2.0 mg/mL) were prepared in normal saline using conventional and alternative compounding methods. Conventional methodology resulted in poorly soluble solutions, with many visible particulates and crystallates. However, special compounding methods, which included incubation of solutions at 50 °C for 50 min followed by storage at 37 °C, were sufficient to solubilize drug. Chemical degradation of MMC solutions was determined over 6 h using high-performance liquid chromatography (HPLC) analytics, while physical stability was tested in parallel.

RESULTS

Immediately following the 50 min incubation, both MMC solutions exhibited approximately 5-7% drug degradation. Based on the measured concentrations and linear regression of degradation plots, additional storage of these solutions at 37 °C for 5 h retained chemical stability criterion (< 10% overall drug loss). No physical changes were observed in any solutions at any test time points.

CONCLUSION

We recommend that the described alternative preparation methods may improve intravesicular delivery of MMC in this urological setting, and advise that clinicians employing these changes should closely monitor patients for MMC toxicities and pharmacodynamics (change in clinical outcomes) that result from the potential enhancement of MMC exposure in the bladder.

Stability of Reconstituted and Diluted Mitomycin C Solutions in Polypropylene Syringes and Glass Vials

: Mitomycin C (MMC) is widely used in treatment of non-muscle invasive bladder cancer at a 1 mg/mL concentration, by intravesical instillation. MMC is also used as an ophthalmic procedure in glaucoma care mostly with 0.2 mg/mL concentration. To accelerate syringes provision, it could be interesting to demonstrate the stability of the drug, in order to be able to prepare the chemotherapeutic drug several hours before the chemotherapy administration.

: A stability indicating HPLC-UV method was developed and validated according to the ICH guidelines. Concentrations of the MMC stored at 25 °C and 60 % of relative humidity and protected from light in polypropylene syringes (1 mg/mL and 0.2 mg/mL) or glass vials (1 mg/mL) were evaluated for 96 h and compared to the initial observed concentrations.

: MMC stability was demonstrated in syringes and glass vials at 1 mg/mL only for 8 h in water for injections and for 10 h at 0.2 mg/mL in 0.9 % sodium chloride solutions, because relative concentrations (95 % confidence interval of the mean of 3 samples) were systematically over 90 % of the initial concentrations. After 96 h the relative concentrations were found below 80 % as compared to initial concentrations, thus indicating instability of these solutions. Degradation products were observed and remained below 3 %.

: This study confirms that MMC solutions for ophthalmic application at 0.2 mg/mL or vesical instillation at 1 mg/mL have to be formulated extemporaneously to maintain the desired concentration.

Sensitive and convenient high-performance liquid chromatographic method for the determination of mitomycin C in human plasma

An improved high-performance liquid chromatographic assay for the cytostatic drug mitomycin C in plasma is presented. The principal steps are precipitation of plasma proteins with acetonitrile, lyophilization of the supernatant and reversed-phase chromatography on a Hypersil ODS 5 microm column with 0.01 M NaH2PO4 buffer (pH 6.5)-methanol (70:30, v/v) in isocratic mode. At a flow-rate of 1.3 ml/min a column pressure of 180-220 bar resulted. Porfiromycin served as internal standard. UV detection was performed at 365 nm. Quantitation limit based on a coefficient of variation <10% in intra- and inter-day assay was 5 microg/l mitomycin C, detection limit based on a signal-to-noise ratio of 3 was 1 microg/l. Recovery was 100% and linearity was shown for the whole range of concentration (1-500 microg/l). None of the five drugs used during chemoembolisation interfered with the assay in vitro. The assay meets the requirements for pharmacokinetic studies of mitomycin C in patients as regards sensitivity and ease of use.

Effect of cyclodextrins on the chemical stability of mitomycins in alkaline solution

The effects of cyclodextrins on the chemical stability of several mitomycin antibiotics in an alkaline medium have been investigated. A stability-indicating high-performance liquid chromatographic method was used to determine the overall degradation rate constants. The influence of various parameters such as structural variations of the cyclodextrins and mitomycins, temperature and pH was studied. It appears that complexation is most favourable with gamma-cyclodextrin. All mitomycin-gamma-cyclodextrin complexes degrade at lower rates than those of the free drugs. Moreover, it was shown that gamma-cyclodextrin influences the equilibrium between mitomycin C and its zwitterion mesomer.

Stability after freezing and thawing of solutions of mitomycin C in plastic minibags for intravesical use

Solutions of 0.6 mg/ml mitomycin C (Mutamycin) in NaCl solution 0.9% in plastic minibags for intravesical use were stored at -20 degrees C and -30 degrees C and thawed by microwave radiation. Both unbuffered solutions and solutions buffered to approximately pH 7.5 were investigated. Concentrations were measured with HPLC. During freezing and storage at -20 degrees C sometimes crystallization of mitomycin C occurred. However, both buffered and unbuffered solutions could be frozen at -30 degrees C during at least four weeks and subsequently thawed without loss of content. Unbuffered mitomycin C solutions could be refrozen at -30 degrees C for another four weeks. Also buffered and unbuffered solutions of another brand of mitomycin C (Mitomycin-C Kyowa) could be frozen at -30 degrees C during four weeks without significant deterioration.

Degradation kinetics and mechanism of N6-[(dimethylamino)methylene]mitomycin C in aqueous solutions

The degradation of N6-[(dimethylamino)methylene]mitomycin C, a semisynthetic analogue of mitomycin C, was studied in aqueous solution. The compound degraded rapidly and followed pseudo-first-order kinetics in both acidic (pH less than 5) and basic pH greater than or equal to 9) media. In the near-neutral pH region, however, biphasic kinetics were observed. At the pH of maximum stability (6.5), 10% activity was lost after approximately 6 h at 22 degrees C. Citrate and phosphate species were catalytic at pH 6.5. Spectrophotometric and HPLC methods were used to elucidate the degradation mechanism at pH 7-9. Under these conditions, equilibrium addition of one water molecule into the amidine side chain occurred, followed by parallel formation of mitomycin C and N6-(formyl)mitomycin C. The latter compound subsequently hydrolyzed to mitomycin C.

Mitomycin antitumour agents: A review of their physico-chemical and analytical properties and stability

The review enumerates the physico-chemical and analytical properties of mitomycin antitumour antibiotics, of which mitomycin C is the most important representative. After a short overview of the position of the compounds in oncology the following subjects will be discussed: structural features, prototropic properties, spectroscopy (UV-VIS, ORD, CD, IR, NMR, MS), chromatography and electrochemistry. The chemical stability and aspects of the mechanism of action of the compounds are also discussed. The last part of the review surveys the analysis of mitomycin C in biological fluids.