Steroids solubilisation

Table 6.11 Micellar solubilisation parameters for steroids in r>alkyl polyoxyethylene surfactants C E (where n = alkyl (C) chain length and m = polyoxyethylene (E) chain length) at 25°C°...

More specific mles can be formulated for particular series of solubilisates. For example, it is clear from studies of the effect of steroid stmcture on solubilisation by a series of surfactants that the more hydrophilic is the substituent in position 17 of the ring stmcture the lower is the quantity of surfactant required to effect solubilisation of the hormone. Thus the extent of solubilisation of hormones in sodium lauryl sulfate follows the series proges-... 

A relationship between the lipophilicity of the solubilisate, expressed by the partition coefficient between octanol and water, Poctanoi (see Chapter 5), and its extent of solubilisation has been noted for the soluhilisation of substituted barbituric acids by polyoxyethylene stearates, of substituted benzoic acids by polysorbate 20, and of several steroids by polyoxyethylene nonionic surfactants. An exhaustive survey of data for the solubilisation of some 64 dmgs by bile salt micelles revealed linear relationships between log (partition coefficient between micelles and water) and log Poctanoi ach of seven bile salts... 

The low solubility of steroids in water presents a problem in their formulation for ophthalmic use. The requirements of optical clarity preclude the use of oily solutions or suspension and there are many examples of the use of nonionic surfactants as a means of producing clear solutions which are stable to sterilisation. In most formulations, solubilisation has been achieved using polysorbates... 

Steroid Algebraic sum Projection sum Solubilisation at 20 (moles/mole of lysophosphatidylcholine) Solubility at 20° (/imoll )... 

Sterols are steroid-based alcohols, the most commonly employed of which is cholesterol (Fig. 28.6). Cholesterol when used in equimolar proportions with a phospholipid is known to condense the packing of the phospholipids in bilayers above Tq thereby reducing their permeability to encapsulated drags. However, it has been shown that the inclusion of cholesterol in the liposome significantly decreases the solubilisation of hydrophobic drugs in the inlayers. 

Figure 29.6 Possible routes of ethanol to cancer. This schematic diagram shows some of the ways in which it is suspected that ethanol may promote carcinogenesis. Although not carcinogenic itself, ethanol can solubilise organic carcinogens that can intercalate between the bases of DNA and cause it to be misread. The metabolism of alcohol generates large amounts of free radicals and reactive oxygen species. These cause peroxidation of lipids and the products of lipid peroxidation can form adducts with DNA and its repair enzymes. The acetaldehyde produced by alcohol oxidation can also do this, but can also induce cell proliferation in some tissues as well as altering the levels of steroid hormones upon which some tumours depend.

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