Apparently glycerine is used as a non polar IV solvent.
Thanks for bumping this thread. I have way more info than that, but I forgot to post it. I was going to post it in response to Solipsis's post. Here are several studies in which THC, et al, were administered to humans intravenously, all of which detail the formulas used. One study is about water-soluble chemical modifications to cannabinoids.
DOWNLOAD
Contents:
Intravenous injection in man of 9 -tetrahydrocannabinol and 11-OH- 9 -tetrahydrocannabinol. Perez-Reyes M, Timmons MC, Lipton MA, Davis KH, Wall ME. Science. 1972 Aug 18;177(4049):633-5.
A comparison of the pharmacological activity in man of intravenously administered delta9-tetrahydrocannabinol, cannabinol, and cannabidiol. Perez-Reyes M, Timmons MC, Davis KH, Wall EM. Experientia. 1973 Nov 15;29(11):1368-9
Oral and parenteral formulations of marijuana constituents. Rosenkrantz H, Thompson GR, Braude MC. J Pharm Sci. 1972 Jul;61(7):1106-12
Development and pharmacokinetic characterization of pulmonal and intravenous delta-9-tetrahydrocannabinol (THC) in humans. Naef M, Russmann S, Petersen-Felix S, Brenneisen R. J Pharm Sci. 2004 May;93(5):1176-84
Pharmacological characterization of novel water-soluble cannabinoids. Martin BR, Wiley JL, Beletskaya I, Sim-Selley LJ, Smith FL, Dewey WL, Cottney J, Adams J, Baker J, Hill D, Saha B, Zerkowski J, Mahadevan A, Razdan RK. J Pharmacol Exp Ther. 2006 Sep;318(3):1230-9. Epub 2006 Jun 6.
And here are books on the preparation of water-insoluble drugs. I had originally come across a preview of the first one when I was Googling to understand more about the preparation of water-insoluble drugs; wasn't able to download it, but came across a full copy of another one listed; and eventually was able to download the first one on bookfi.org and came across even more books on the topic via their search and eventually downloaded all the ones listed below. I recommend
http://libgen.org because it searches BookFi and it's a bigger operation (the highlight is the scientific articles search engine). Best source for ebooks I've come across is the invite-only
http://ebook.farm btw (includes academic books).
Formulating Poorly Water Soluble Drugs (AAPS Advances in the Pharmaceutical Sciences Series). Robert O. Williams III, Alan B. Watts and Dave A. Miller (2011)
Water-Insoluble Drug Formulation. Rong Liu (2008)
Microemulsions: Properties and Applications. Monzer Fanun (2008)
Handbook of Microemulsion Science and Technology. Promod Kumar & K.L. Mittal (1999)
Microemulsions: Background, New Concepts, Applications, Perspectives. Cosima Stubenrauch (2008)
Good definition of emulsion, the type of formula used for IV cannabinoids.
Source:
http://pharmlabs.unc.edu/labs/emulsions/intro.htm
Introduction
An emulsion is a thermodynamically unstable two-phase system consisting of at least two immiscible liquids, one of which is dispersed in the form of small droplets throughout the other, and an emulsifying agent. The dispersed liquid is known as the
internal or discontinuous phase, whereas the dispersion medium is known as the
external or continuous phase. Where oils, petroleum hydrocarbons, and/or waxes are the dispersed phase, and water or an aqueous solution is the continuous phase, the system is called an oil-in-water (o/w) emulsion. An o/w emulsion is generally formed if the aqueous phase constitutes > 45% of the total weight, and a hydrophilic emulsifier is used. Conversely, where water or aqueous solutions are dispersed in an oleaginous medium, the system is known as a water-in-oil (w/o) emulsion. W/O emulsions are generally formed if the aqueous phase constitutes < 45% of the total weight and an lipophilic emulsifier is used.
Emulsions are used in many routes of administration. Oral administration can be used, but patients generally object to the oily feel of emulsions in the mouth. But some times, emulsions are the formulation of choice to mask the taste of a very bitter drug or when the oral solubility or bioavailability of a drug is to be dramatically increased.
More typically, emulsions are used for topical administration. Topical emulsions are
creams which have emollient properties. They can be either o/w or w/o and are generally opaque, thick liquids or soft solids. Emulsions are also the
bases used in lotions, as are suspensions. The term "lotion" is not an official term, but is most often used to describe fluid liquids intended for topical use. Lotions have a lubricating effect. They are intended to be used in areas where the skin rubs against itself such as between the fingers, thighs, and under the arms.
Emulsions are also used
a ointment bases and intravenously administered as
part of parenteral nutrition therapy. Their formulation and uses in these roles will be covered in the appropriate chapters.
The consistency of emulsions varies from easily pourable liquids to semisolid creams. Their consistency will depend upon:
the internal phase volume to external phase volume ratio [*]in which phase ingredients solidify [*]what ingredients are solidifying
Stearic acid creams (sometimes called vanishing creams) are o/w emulsions and have a semisolid consistency but are only 15% internal phase volume. Many emulsions have internal phases that account for 40% - 50% of the total volume of the formulation. Any semisolid character with w/o emulsions generally is attributable to a semisolid external phase.
W/O emulsions tend to be immiscible in water, not water washable, will not absorb water, are occlusive, and may be "greasy." This is primarily because oil is the external phase, and oil will repel any of the actions of water. The occlusiveness is because the oil will not allow water to evaporate from the surface of the skin. Conversely, o/w emulsions are miscible with water, are water washable, will absorb water, are nonocclusive, and are nongreasy. Here water is the external phase and will readily associate with any of the actions of water.
Emulsions are, by nature, physically unstable; that is, they tend to separate into two distinct phases or layers over time. Several levels of instability are described in the literature.
Creaming occurs when dispersed oil droplets merge and rise to the top of an o/w emulsion or settle to the bottom in w/o emulsions. In both cases, the emulsion can be easily redispersed by shaking.
Coalescence (breaking or cracking) is the complete and irreversible separation and fusion of the dispersed phase. Finally, a phenomenon known as
phase inversion or a change from w/o to o/w (or vice versa) may occur. This is considered a type of instability by some.
