Hi All,
I just prepare 50 mg/ml furosemide in NaOH, then try to adjust pH with HCL. We hope the pH for this buffer is around 7, well we also accept 8 or 9. however, when pH drop a little bit lower than 10, many white furosemide was coming out and didn't dissove any more. and pH 10 is too high for our animal study. Is there any buffer I can try for prepare furosemide and let it pH become lower?
Thanks
Yiyun
Looks like the furosemide molecule has several sites that can protonate/deprotonate -- your problem is likely to be that at pH 7 it's (functionally) neutral, hence not very soluble (the carboxylate will be deprotonated, but the secondary amine will be protonated, hence net neutral). You might try chelating it with a cyclodextrin. You can't cheat nature on pH issues, really. Depending on the administration route, could you use a co-solvent to increase solubility, perhaps, or if slower release is acceptable, load it as a suspension (by gavage, or subcutaneous depot injection)?
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