Although one of my drugs co-crystal is showing high melting point in comparison to others but its dissolution rate is better than the other forms... is it possible... Usually we find lower the melting point better the dissolution profile.....
There is no relationship of melting point and dissolution profile of drug or cocrystals. If there's a relationship between them, than eutectic should have higher dissolution profile compared to cocrystals. So, we can't predict the dissolution profile on the basis of melting point.
Hello.
I don't have any examples for co-crystals, but the ideas below may help to explain what you are seeing. I apologize for the over-simplified examples, but they hopefully illustrate a basic concept that might be helpful to you.)
While there can be a relationship between melting points and dissolution or solubility, it is not universal. The melting point is a reflection of the lattice interactions between the solid-state molecules, while dissolution considers the lattice energy plus the hydration energies.
For instance, if you consider a molecule for which the lattice energies are strong compared to hydration energy, the solubility or dissolution is poor and increasing the melting temp (say by a different molecular arrangement that increases the strength of the lattice energy) would be expected to decrease the solubility or dissolution.
If another molecule has a hydration energy that is stronger relative to the lattice energy, increasing the lattice energy will likely have less of an effect on the solubility or dissolution.
The situation for a co-crystal is potentially more complicated because there are two molecules and two hydration energies to consider, which introduces variations that could (at least in theory) make it possible to have a higher melting temp and faster dissolution.
Food for thought!
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