Why are the ingredients in most pills WHITE in color?
Many have a colored covering but the ingredients are usually white. I even suspect that many ingredients start out white but are tinted for identification purposes. (Rx Valium is yellow, while generic is pink.) It seems like medicinal chemicals would come in a variety of colors.
I imagine that in most of the cases, most of the pill isn’t actually composed of the medicine. There’s probably only very small amounts, mixed in with some sort of binder, and the binder is white.
The fact is, most organic compounds are white. The reality is that organic compounds that absorb in the visible range are a special case where electronic transitions are made low enough energy that they absorb in the visible range. Usually, the compounds that do absorb in the visible range, tend to be rigid and flat which is not a common configuration to fit in the active site of some protien receptor or whatever. So they don’t usually make good drugs.
Chromophores almost always arise in one of two forms: conjugated pi systems and metal complexes. Most useful drugs do not have extended stretches of conjugated double bonds, and are not metal complexes.
Right, and conjugated pi systems tend to be rigid and flat.
And just to demonstrate that nothing that’s been said here is strictly true cisplatin is both a metal complex and rigid and flat. But it’s not a conjugated pi system. I’m not sure of it’s color. I’ve got more experience with platinum metal complexes than most and I can say similar compounds are colorless.
According to a Discovery show I was watching a while back (I think it was How It’s Made), titanium dioxide is commonly added to pills to ensure a uniform colouring.
Another reason not to have coloured pills is to stop kiddies thinking they are sweets. Also it is a slight complication when compounding the pill to add colour, so why bother? Also adults tend to associate white with medicine, so blue pills may make them suspicious
Not ALL blue pills, obviously…
Yeah, my wife’s always going on about how “somebody” needs the “little blue pill.” What’s that all about?
On a related note, I was recently wondering why ibuprofen makers tend to go for brightly colored coatings on their pills. Nuprin is bright yellow, Motrin is bright orange …
Viagra is a little blue pill. Sometimes pills are colored, I think, to make them easy for the pharmacist to identify. I know of one case where the slow release form is slightly blue and the quick release form is slightly pink. At least I think that is the way it was. The medication itself is almost always white.
The small particle size aof any of the ingredients in a tablet (pharma manufacturere dont’ make pills anymore) is very small. This allows for precise ,measuring, blending and better compaction. Anything of a small enough particle size appears white. Think ice cube, vs crushed ice. There is enough refraction and reflection to show all colors.
Ther is no commercial reason to color the inside of a coated tablet. Just the outside.
I understand what you are saying here, but this is only true for compounds that don’t significantly absorb in the visible range. It just happens, that most compounds don’t. Water does not absorb in the visible range, but I don’t care how finely you grind a merocyanine dye, it will never be white. A dye will not reflect or refract what it absorbs.