The reasons I prefer suspension or solution over capsules are multiple:
- Homogenization is much more readily achieved.
- Alterations in homogeneity are often visible with liquids; in contrast to active ingredients and capsule fillers which are often the same color
- Incremental dosing with accuracy is possible with liquid medications
- Medications are more rapidly and readily absorbed in liquid form
- The little bottles and syringe adapters are neat and unique to my products in the underground
Like most liquids, the suspension vehicle's viscosity will be altered by temperature. The vehicle is formulated to suspend particles at room temperature. I feel certain that some of the suspension property would change with decreased viscosity that commonly is associated with heating liquids.
Within reason, this suspension vehicle will return to its normal state after reaching room temperature following a period of higher temperature.
Now, this does not apply to excessive temperatures, such as boiling or near boiling. I'm sure that would alter the vehicle permanently; so I definitely would not recommend that. I can't fathom a reason for such an action either.
One person asked me about the stability of his suspension that was in the mailbox for a few hours during the day. I believe it will return to its original state upon reaching room temperature following a period of mild temperature increase like that. It would be safe to use.
Bioavailability is not affected by the suspension vehicle. For bioavailability of a medication to be altered, processes which change the absorption or chemical properties of the medication must be applied; or the route of administration must be changed.
These suspensions are identical to the vehicle that pediatric acetaminophen, and many other drugs are compounded in.
If you have young children, chances are you probably have filled a prescription for them that was in liquid form. Many medications are not commercially offered in suspension; so they are created by a compounding pharmacist. The compounding pharmacist will take the medication, often in tablet form; and pulverize it in a mortar and pestle. Then the powdered tablets are homogenized into suspension with the very same vehicle that I am using for my products. In fact, I pick it up from a place that does exactly that.
Yes, you have to shake them. There is nothing available that will defy the law of gravity. If left alone long enough, any medication will settle out of suspension. Even Children's Tylenol must be shaken prior to dosing. The R&D behind the suspension vehicles used today in compounding pharmacy has proven that shaking the container, after a period of being motionless, will redistribute the medication to nearly the same degree of homogeneity as when it was first compounded.
I hope that answers your questions.