I recommend Cremophor EL.

If the purpose why you use DMSO is to act as a vehicle for your drug, then you will have to give your normal. Control DMSO to cancel out DMSO effects in all groups. But I advice check if your drug may dissolve in other solvents such as normal saline, warm water etc

Often time 1 or 2% is mostly recommended for in vitro studies because of its toxicity. So, if you must use 5% DMSO as vehicle in vivo, I will advise you to run a preliminary study to confirm its toxicity in the animal. The concern is the duration of treatment in the animal. Because of that, it will be imperative to follow Emmanuel advice. Well done Arya!!!

The concentration of DMSO used for dissolution of extracts must be used same for controls. I advice you try lower concentrations to see the lowest percentage of DMSO that dissolves the highest concentration of the extract.

Worth considering the FDA recommendation for oral DMSO as an inactive ingredient - DIMETHYL PHTHALATE ORAL TABLET, SUSTAINED ACTION 131113 08X7F5UDJM 0.41MG

https://www.accessdata.fda.gov/scripts/cder/iig/index.cfm

Thanks for your helpful answers.

In response to Michael contribution using 10% dmso in vitro and 0.5% in vivo is confusing. Please clarify further... people can publish stuff but it is better to confirm it.

Dear Dharmendra

Why you need to solubilize the drug in 5% DMSO which may be toxic to rats when the intended route is oral. As per my suggestion you can use a suspending agent like gum acacia (1 to 5 %) to make a suspension which may be administered by oral gavage as vehicle control.

Hi

you must used DMSO at the same concentration of drug to exclude any effect of DMSO on biological function. but I advice you to decrease the amount of the solvent on both drug and control group if you can.