Simple ammonium salts acting on sigma-1 receptors yield potential treatments for cancer and depression.

Sigma-1 and sigma-2 receptors are emerging therapeutic targets. We have identified that simple ammonium salts bind to these receptors and are effective in vivo. Radioligand binding assays were used to obtain structure-activity relationships of these salts. MTS assays were performed to determine their effect on growth in MCF7 and MDA-MB-486 cells. Anticancer properties were tested in NMRI mice transplanted with a fragment of mouse adenocarcinoma (MAC13). Antidepressant activity was tested using the forced-swim test and tail suspension tests. Dipentylammonium (Ki 43 nM), tripentylammonium (Ki 15 nM) and trihexylammonium (Ki 9 nM) showed high affinity for the sigma-1 receptor. Dioctanoylammonium had the highest affinity (K50 0.05 nM); this also showed the highest affinity for sigma-2 receptors (Ki 13 nM). Dipentylammonium was found to have antidepressant activity in vivo. Branched-chain ammonium salts showed lower affinity. Bis(2-ethylhexyl)ammonium (K50 29 µM), triisopentylammonium (K50 196 µM) and dioctanoylammonium showed a low Hill slope, and fitted a 2-site binding model for the sigma-1 receptor. We propose this two-site binding can be used to biochemically define a sigma-1 receptor antagonist. Bis(2-ethylhexyl)ammonium and triisopentylammonium were able to inhibit the growth of tumours in vivo. Cheap, simple ammonium salts act as sigma-1 receptor agonists and antagonists in vivo and require further investigation.

Concentration Accuracy of Compounded Mitomycin C for Ophthalmic Surgery.

IMPORTANCE: Ophthalmologists rely on accurate concentrations of mitomycin C (MMC) to prevent scarring with trabeculectomy surgery. To our knowledge, the concentration accuracy and variability of compounded MMC are unknown. OBJECTIVE: To determine whether the measured concentration differs from the expected concentration of 0.4 mg/mL of MMC used in ophthalmic surgery. DESIGN, SETTING, AND PARTICIPANTS: Laboratory experimental investigation conducted in July 2013. We acquired 60 samples of 0.4 mg/mL of MMC from a spectrum of common compounding and storage techniques (refrigeration, freezing, and immediately compounded dry powder) and a variety of pharmacies (an academic hospital, a community hospital, and an independent Pharmacy Compounding Accreditation Board-accredited pharmacy). We used C18 reversed-phase high-performance liquid chromatography to measure the MMC concentration of all samples. We used pure MMC (Medisca Inc) to generate calibration curves and sulfanilamide as an internal standard. MAIN OUTCOMES AND MEASURES: We calculated MMC concentration using a calibration curve (range, 0.3-0.5 mg/mL) generated by dividing MMC peak area by internal standard peak area and plotting the area ratio against the calibrant concentrations. We compared the measured concentration against the expected 0.4 mg/mL concentration for all samples. RESULTS: Measurement of MMC using the high-performance liquid chromatography method demonstrated acceptable accuracy (92%-100%), precision (2%-6% coefficient of variation), and linearity (mean correlation coefficient of r2 = 0.99). The measured MMC concentration determined using the high-performance liquid chromatography method for all samples was 12.5% lower than the expected 0.4 mg/mL value (mean [SD], 0.35 [0.04] mg/mL; 95% CI, 0.34-0.36; P < .001) with a wide concentration range between 0.26 and 0.46 mg/mL. CONCLUSIONS AND RELEVANCE: Common compounding and storage techniques for MMC resulted in a lower accuracy and wider range of concentration than expected. These differences in concentration may result from compounding techniques and/or MMC degradation. Variability in MMC concentration could cause inconsistency in glaucoma surgical results, but the clinical relevance of such findings on glaucoma surgery outcomes remains unknown.

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%, ß=-0.1%/h, P<0.001) and shipment on-ice (93.1±1.8%, ß=-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.

Ketogenic diet prevents epileptogenesis and disease progression in adult mice and rats.

Epilepsy is a highly prevalent seizure disorder which tends to progress in severity and become refractory to treatment. Yet no therapy is proven to halt disease progression or to prevent the development of epilepsy. Because a high fat low carbohydrate ketogenic diet (KD) augments adenosine signaling in the brain and because adenosine not only suppresses seizures but also affects epileptogenesis, we hypothesized that a ketogenic diet might prevent epileptogenesis through similar mechanisms. Here, we tested this hypothesis in two independent rodent models of epileptogenesis. Using a pentylenetetrazole kindling paradigm in mice, we first show that a KD, but not a conventional antiepileptic drug (valproic acid), suppressed kindling-epileptogenesis. Importantly, after treatment reversal, increased seizure thresholds were maintained in those animals kindled in the presence of a KD, but not in those kindled in the presence of valproic acid. Next, we tested whether a KD can halt disease progression in a clinically relevant model of progressive epilepsy. Epileptic rats that developed spontaneous recurrent seizures after a pilocarpine-induced status epilepticus were treated with a KD or control diet (CD). Whereas seizures progressed in severity and frequency in the CD-fed animals, KD-fed animals showed a prolonged reduction of seizures, which persisted after diet reversal. KD-treatment was associated with increased adenosine and decreased DNA methylation, the latter being maintained after diet discontinuation. Our findings demonstrate that a KD prevented disease progression in two mechanistically different models of epilepsy, and suggest an epigenetic mechanism underlying the therapeutic effects.