Activity of dissolved mitomycin C after different methods of long-term storage

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.

Type 1 Diabetes: an Association Between Autoimmunity, the Dynamics of Gut Amyloid-producing E. coli and Their Phages

The etiopathogenesis of type 1 diabetes (T1D), a common autoimmune disorder, is not completely understood. Recent studies suggested the gut microbiome plays a role in T1D. We have used public longitudinal microbiome data from T1D patients to analyze amyloid-producing bacterial composition and found a significant association between initially high amyloid-producing Escherichia coli abundance, subsequent E. coli depletion prior to seroconversion, and T1D development. In children who presented seroconversion or developed T1D, we observed an increase in the E. coli phage/E. coli ratio prior to E. coli depletion, suggesting that the decrease in E. coli was due to prophage activation. Evaluation of the role of phages in amyloid release from E. coli biofilms in vitro suggested an indirect role of the bacterial phages in the modulation of host immunity. This study for the first time suggests that amyloid-producing E. coli, their phages, and bacteria-derived amyloid might be involved in pro-diabetic pathway activation in children at risk for T1D.

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.

The Degradation of Mitomycin C Under Various Storage Methods

PURPOSE

To compare the effects of common pharmacy preparation and storage conditions on the stability of mitomycin C (MMC) in solution.

METHODS

We used C18 reversed-phase high-performance liquid chromatography to determine the stability of 0.4 mg/mL MMC solutions, and liquid chromatography-electrospray ionization-mass spectrometry to identify degradation products. Conditions compared were: compounding and storage by refrigeration (1 and 2 wk), freezing (23 d), shipment "on-ice" (1 mo frozen followed by 1-wk refrigeration), and immediately compounding dry powder (Mitosol; Mobius Therapeutics LLC). We tested 3 samples for each storage method when samples reached room temperature (time 0), and then 1, 4, and 24 hours later. We used MMC peak area as a percentage of total (MMC plus degradants) area detected with high-performance liquid chromatography as a measure of stability.

RESULTS

We assessed MMC stability for 5 preparation and storage methods at 4 timepoints (with n=3 per timepoint). At time 0, we found similar stabilities for MMC (F=0.72, P=0.599) between all 5 storage methods: 1-week refrigerated (97.9±0.2%), dry powder (97.5±0.3%), 2-week refrigerated (96.9±0.2%), 23-day frozen (96.7±3.1%), and shipment on-ice (96.0±1.2%). However, MMC demonstrated significant degradation over a 24-hour period with 2-week refrigeration (95.7±0.3%, β=-0.1%/h, P<0.001) and shipment on-ice (93.1±1.8%, β=-0.1%/h, P=0.013). We identified small amounts (<3.2%) of 2 degradants, cis-hydroxymitosene and trans-hydroxymitosene, across all samples.

CONCLUSIONS

The different preparation and storage methods of MMC showed similar stability when used immediately upon reaching room temperature. However, degradation of MMC occurred with further storage at room temperature. The clinical implication of small amounts of MMC degradants is unclear.

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.

A review of the efficacy of mitomycin C in glaucoma filtration surgery

The success of trabeculectomy, which is considered the gold standard in the surgical treatment of glaucoma, depends on the wound healing response. The introduction of antiproliferative agents such as mitomycin C (MMC) has increased the success rates of trabeculectomy. However, complications due to these agents can be challenging to manage. Hence, it is important to determine the most efficacious dose and duration of exposure. Multiple studies suggest that many factors, including but not limited to MMC preparation, different concentrations, different exposure times, and method of application may affect success rate, and these factors were reviewed in this article. We concluded that lower concentrations of MMC that are prepared and applied in a standardized fashion, such as that using the Mitosol(®) kit (for 2-3 minutes) during trabeculectomy, could potentially provide trabeculectomy success rates similar to that reported with off-label preparations, and that such a treatment regime could result in in lower complication rates than higher doses of MMC.

Adjustable release of mitomycin C for inhibition of scar tissue formation after filtration surgery

The aim of this study is to demonstrate a drug delivery system with the capacity to adjust the release of mitomycin C (MMC), based on polymer composition, and inhibit fibroblast proliferation to a better effect than is currently used in glaucoma filtration surgery. The polymer used in this work is made from the oligosaccharide cyclodextrin, from which others and we have demonstrated adjustable release of small molecule drugs due to specific molecular interactions or "affinity" between drug and the cyclodextrin polymer. To adjust release rate, cyclodextrin polymers were synthesized in either dimethylformamide (DMF) or dimethyl sulfoxide, (DMSO) at a crosslinking ratio of 1:0.16 or 1:0:32 (molecule of glucose: molecule of crosslinker). The polymers were then loaded with mitomycin C, dried, and release evaluated in a physiological environment. Drug release was determined by visible spectroscopy. Released aliquots of mitomycin C were incubated with 3T3 fibroblast cells to determine cytotoxic or inhibitory effect through a cell proliferation assay. We show that by using affinity between drug and polymer, we can adjust MMC release rates to be slower and more sustained than from conventional, diffusion-only polymers, for both the DMF polymers (p = 0.00526) and the DMSO polymers (p = 0.0113). The incorporated and released MMC maintains inhibition of fibroblast proliferation much longer than is possible with a one-time application. Affinity polymers with 1:0.16 and 1:0.32 crosslink ratio showed significant inhibition of proliferation for up to 100 h (p = 0.018 and p = 0.014 respectively). The use of our controlled drug delivery technology applied after surgery could have a greater therapeutic impact than the current one-time applications of MMC.

Evaluation of the Stability of Extemporaneously Prepared Ophthalmic Formulation of Mitomycin C

Mitomycin C (MMC) is a cytostatic agent topically used in conjunctival neoplasms, secondary to glaucoma filtering, pterygium, and strabismus surgery to increase the success rate. The topical formulation of MMC for ocular use is always extemporaneously prepared. Our study evaluated the stability of extemporaneously prepared formulations of MMC at different concentrations (150, 300, & 600 microg/mL) kept at different temperatures (25 degrees , 4 degrees , and -70 degrees C) and at different pH range (6, 7, and 8). Aliquots from the above formulations were subjected for quantification of MMC on days 0, 7, 14, 21, and 28 using high-performance liquid chromatography. MMC stored at 25 degrees C for 6 months was also subjected to flow cytometry and compared to freshly prepared MMC. The results indicated that the degradation of MMC is very high in acidic pH at room temperature. Increasing the pH to 7 or 8 and keeping MMC at low temperatures significantly decreased the degradation of MMC. Interestingly, the flow cytometry data revealed that the 6-month-old MMC showed an antiproliferative effect compared to that of freshly prepared MMC. To conclude, the extemporaneously prepared MMC at pH between 7 and 8 and stored in the refrigerator can increase the duration of its stability. However, the antiproliferative study using flow cytometry revealed that degraded MMC retained its activity even after degradation.