Glucosamine based topical analgesics, in testing, has been shown to temporarily reduce pain in the direct area where applied as it penetrates the skin, but there is no real lasting effect.
Glucosamine capsules on the other hand, are better suited to reducing the pain over a long period of time and slowing the progression of osteoarthritis joint deterioration. Using pills, however, one is still not realizing the full potential of glucosamine. This is for two reasons.
First, many pills in the marketplace contain a great deal of fillers, binders, coatings, and disintegrants that do not provide any help with your problem and some may actually interfere with the absorption and bioavailability of the active ingredients of the product that you are trying to have your body absorb. If a company can sell you fillers and binders instead of more expensive active ingredients, they can pad their profits while reducing the benefits to you of using the product.