http://circ.ahajournals.org/cgi/content/full/99/16/2164 describes a vehicle for rapamycin injection consisting of a rapamycin suspension in 0.2% carboxymethyl cellulose and 0.25% polysorbate-80. They don't say how the suspension was done; one way is to thoroughly agitate or grind the rapamycin in the vehicle. Another way, probably better and easier, is to dissolve the rapamycin at high concentration in DMSO, dimethylformamide or dimethylacetamide, then dilute into the aqueous vehicle--this should give a very fine suspension if agitation is good during addition of the DMSO solution. Injection was i.m. Gallo, R., et al. "Inhibition of Intimal Thickening After Balloon Angioplasty in Porcine Coronary Arteries by Targeting Regulators of the Cell Cycle." Circulation 99: 2164-2170 (1999).
http://www.pnas.org/cgi/reprint/96/15/8657.pdf describes a similar protocol; these workers dissolved the rapamycin in dimethylacetamide, then added it in 1:24 proportion to a vehicle of (final conc.'s) 10% polyethylene glycol (MW avg. = 400) and 17% polyoxyethylene sorbitan monooleate. Injection was i.p. in mice, total vol. of 100 µl. Rivera, V.M., et al. "Long-term regulated expression of growth hormone in mice after intramuscular gene transfer." Proc. Natl. Acad. Sci. USA 96: 8657-8662 (1999).
http://ajpendo.physiology.org/cgi/content/full/279/5/E1080 used 0.75 mg/kg rapamycin in 5% dimethyl sulfoxide, for injection into pigs via jugular vein catheter. Kimball, S.R., et al. "Feeding stimulates protein synthesis in muscle and liver of neonatal pigs through an mTOR-dependent process." Am. J. Physiol. Endocr. Metab. 279: E1080-E1087 (2000).
http://www.bloodjournal.org/cgi/content/full/100/3/1084 injected rapamycin in 51% wt/vol polyethylene glycol 300 (PEG300), 2.5% wt/vol polysorbate 80, 10% vol/vol ethanol, i.p. Hackstein, H., et al. "Rapamycin inhibits macropinocytosis and mannose receptor-mediated endocytosis by bone marrow-derived dendritic cells." Blood 100: 1084-1087 (2002).
http://cancerres.aacrjournals.org/cgi/content/full/62/24/7291 injected rapamycin i.p. in mice by diluting an ethanol stock solution of rapamycin first into sterile 10% PEG400/8% ethanol and then that solution was further diluted into an equal volume of sterile 10% Tween 80 for a final concentration of 20 µg rapamycin/100 µl. (Most of this information is in the Materials and Methods section of the paper, but the "ethanol stock solution" is mentioned under the Cell Culture and Antibodies section, and the additional details are found in the Regrowth Delay Assay section.) Eshleman, J.S., et al. "Inhibition of the Mammalian Target of Rapamycin Sensitizes U87 Xenografts to Fractionated Radiation Therapy" Cancer Res. 62: 7291-7297 (2002).