Try serum.

Hi Shambhu, thanks for the reply. But I am not sure what you mean by serum? I cannot add serum to the Ringer solution and in the cell culture medium I use, there is already 20% serum in it. Please let me know if you have some other trick to solubilize Cyclosporin A.

Hi Amit, did you ever find a way to dissolve the CsA in ACSF? I'm having the same problem! Hope the hear from you, thanks in advance!

Hi Aile, thanks for following up. I have tried various tricks for solubilizing CsA at the final concentration of 20 µM such as solubilization at high and low temperatures, at low pH (around 6.3), sonication or even adding a little bit of tween-80, etc. Until now I did not get any success in the complete solubilization of CsA in the aqueous solutions such as ACSF. So my strategy was to stir CsA in ACSF at the room temperature for 1-2 hours and use that solution for my physiology experiments. I had some CsA precipitates floating around in the solution; you can use the vacuum filter to get rid of them. Once dissolved and filtered, I didn't see CsA falling off from the solution. I am surprised that there are so many studies that use 20 µM CsA regularly and don't report about the solubility problem with this drug or if they have come up with some trick. Interestingly there is a paper that examined the solubility of CsA in aqueous solution (see attached paper by Ran et al., Solubilization of cyclosporin A.(2001)), and it seems they can get CsA solubilized at the final concentration of about 20 µM. However, their method didn't work out for me. I hope this is helpful, if you find a way to get CsA into the aqueous solution, please do share the protocol with the community.

Article Solubilization of cyclosporin A

Hi, I ran into the same problem of my cyclosporin dDMSO solution precipitating when I added it to ACSF used for brain-slice recordings.  It was solved by ordering the 1 mg/ml stock from Sigma, and diluting that appropriately. I used it at 1 uM in the internal recording solution (Li et al., 2003).

I came across the paper "unnusual solubility behaviour of cyclosporin A in aqueous media" which describes that Cyclosporin A is 10 times more soluble in an aqueous solution at 5 degrees compared to 37 degrees.

I made a 10 mM solution of Cyclosporin A in DMSO and did a 1/5 dilution (2 mM) in water, vortexed and put it in the fridge. After 1-2 hours the solution was soluble. Then I could make further dilutions in water and it was still soluble (did not percipitate). I then put it in PBS and CsA seemed to function. This might be helpfull to others :)

Thanks Helena for sharing your experience with CsA solubility. I will give it a try and will let you know about my experience.

Thanks a lot @ Helena Midtboe .. It worked so well for me...