Dissolution rates and apparent solubilities for synthetic hydroxyapatite in acetate buffers containing phosphate and strontium ions in the range of 10-3 to 10-2 M were determined under various pH and buffer conditions. Critical examination of the role of strontium with a physical model suggests that a calcium-strontium apatite surface complex may govern the driving force of the dissolution reaction.

In contrast to earlier studies on aliphatic amines,23'27 this indicates that ion energetics can be a useful tool in characterizing the structural isomers of CaHeN"1'.In the cases of C2H5O4• isomer II and isomer III in both sets, it is seen that gaseous ion properties obtained from ion-molecule reaction chemistry studies are most useful in the interpretation of ion energetics data.

These findings indicate that to formulate DTM HCl into a hydroxypropyl methylcellulose gel the enhancers of choice should be polysorbate 80, myristic acid, DMSO, NMP, and IPM or combinations thereof.

Dissolution of human dental enamel and of synthetic hydroxyapatite pellets in completely unsaturated acetate buffer solutions was previously shown to follow a model in which a single dissolution site was employed. The present investigation reports similar studies carded out under the clinically more relevant conditions of dissolution into solutions partially saturated with respect to hydroxyapatite, and it is shown that under these conditions the dissolution kinetics may be described by a site which has properties different from the site responsible for dissolution into completely unsaturated solutions. The properties of this second site were consistent with experiments in which bulk solution conditions (degree of partial saturation, Ca/P ratio) and effective diffusion layer thickness were varied. Thus, dissolution kinetics studies indicate that hydroxyapatite crystals have at least two different types of sites that are important in dissolution.

Of the 73 drugs evaluated, 64 were compatible and 7 were incompatible with ceftaroline fosamil 2.22 mg/mL in 3 standard infusion solutions. Nine drugs in 23 admixtures were observed to exhibit signs of incompatibility with ceftaroline fosamil within four hours of mixing; those drugs should not be simultaneously administered via a Y-site with ceftaroline preparations.