Dear Madhavan,

The answer is yes. Please read the following text and for more details see the attached file:

CRYSTAL SUSPENSIONS OF INSULIN

DERIVATIVES, PROCESSES FOR THEIR

PREPARATION AND THEIR USE

The crystallization of insulin is an intensively re searched ?eld, both in respect of work on structural analysis (Adams et al., Nature 224, 491 (1969), The Peking Insulin Structure Research Group, Sc. Sinica XVIII, 152-118 (1974)) and in respect of pharmaceutical applications (Schlichtkrull, Insulin-Kristalle (Insulin Crystals) (1961)). For therapeutic use as a delayed action form of insulin, a crystal size which can be de?ned as far as possible and usually should not exceed about 30

um, so that there is a direct and reproducible relation ship between the surface and the absolute amount of insulin, is of chief importance here. De?ned redissolv

ing kinetics are to be expected with such so-called monodisperse suspensions.

Examples of insulin crystal suspensions which are used therapeutically and have such properties are suspensions of rhombohedral zinc-insulin crystals which are about 25 pm in size, are stable in the presence of 0.8 to 2.5% of zinc (based on the weight of insulin) at a neutral pH value and exhibit a delayed action, and isophane insulin protamine crystals which are used in delayed action products in the form of small rods about 10 um long and about 1 pm thick. A few other crystal modi?cations of insulin are furthermore known, but these have hitherto been of interest only for X-ray structure analysis. Thus, zinc-free orthorhombic and monoclinic crystals have been obtained under acid pH conditions (Einstein, Low, Acta Cryst. 15, 32-34 (1962)). Smaller rhombic dodecahedra, which are to be classi?ed in the cubic space group, have been obtained at the isoelectric point, also in the ab sence of zinc (Schlichtkrull, Insulin-Kristalle (Insulin Crystals) (1961)). Finally, a monoclinic crystal form of insulin has also been described, likewise by Schlicht krull, which has been obtained above the isoelectric point in the presence of zinc and in the presence of phenol or phenol derivatives. These crystals grow to a considerable size (up to 3 mm) within a few days and have sharp edges. Interestingly, these crystals have been found only on glass surfaces and not on the free surface of the solution (Schlichtkrull, Insulin-Kristalle (Insulin Crystals), pages 57-60, (1961)).

Hoping this will b e helpful,

Rafik

Unfortunately, none of these provide concrete answers to my query.