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Drug Administration, in vivo - Advice on choosing an injection vehicle (May/16/2007 )

I'm planning an experiment where I'll be injecting a Hedgehog agonist drug (Purmorphamine) into rats to study the effects of this drug on bone growth. I'm not sure what solvent to use that will allow systemic availability (as opposed to local only). All of the ring groups suggest (at least to to me, the neophyte) that it is fairly hydrophobic, and it is reported to be cell permeable, and small (520 Da) so I'm considering using 2-hydroxypropyl-b-cyclodextrin (45% w/v, in saline), as it is the vehicle for a similarly sized steroidal-alkaloid drug I'm testing in parallel.

The vendor for the compound only suggests solubility in DMSO (up to 200mg/ml), which I use for in vitro studies, but does not suggest any other solvent in the product insert or MSDS Web: <>. I can't seem to find any literature suggesting this compound has been used in vivo before. It's a relatively new compound, so the breadth of solvents which may be useful are not well known, but I was hoping that someone with a more extensibe background in drug development/pharmacy may have an opinion based on the structure/formula aspect. Thanks in advance for any suggestions!


deciding a vehicle for your drug takes a whole lot of your time.
since ur drug is lipophillic, i would recommend several solvents like PEG 400, cremophor EL mixed with ethanol and water. for e.g drug dissolved in ethanol:cremophor el: water in the ratio 1:1:9. this make some sort of micelles and before injection(IP) make sure you vortex the suspension. there are several papers listing variety of vehicles if you search for them.
hope this helps


It certainly might be a viable choice since you are already looking at the vehicle in other application.

Don't overlook the addition of pH control. I recently worked with a compound in HBC that required additional pH control to 2.8 to get it into solution. it remained stable over several weeks.

Once into solution, be sure to trial stability at room and 4 degree temps. I do not accept anything that does not stay stable over 3 hours.

One hint for bringing up compounds dissolved first in DMSO is to add your excipient very slowly in a close to drop wise fashion and to not vortex or mix / shake strongly. It can contribute to instability.

The process of developing skills in formulation is a long one of trail and error. Best skill I learned at my last job was getting client novel compounds into solution for in-vivo work.