Yep. Glucosamine hydrochloride has greater bioavailability than glucosamine sulfate. Brands using the sulfate won't work as well.
Chondroitin sulfate is this huge molecule that's difficult for the body to absorb. The best sort is refined to a lower molecular weight. Unfortunately, the label won't tell you if the supplement is made with highly refined chondroitin or el-cheapo ground up shark bits.
All the actual studies reporting that glucosamine/chondriotin supplements work (for dogs, at least) were done using the 'Cosequin' brand, made by Nutramax labs. It is really expensive and has the chondriotin of the lowest molecular weight anybody can get, or so Nutramax claims.
Nutramax markets their veterinary-use supplements for dogs, cats, and horses under the name of 'Cosequin' but also offers a variant intended for humans, called 'Cosamin.' It's the same, except for the little bit of maganese being a slightly different level. 'Cosamin' for humans is cheaper than 'Cosequin' for dogs, and you can buy 'Cosamin' at Wal-Mart. (The shelf of glucosamine supplements at the Wal-Mart around here is huge and confusing, you will have to look hard. The "Cosamin" bottle comes in a box.)
Research says, glucosamine works best in a complex with chondriotin, and without adequate manganese in the diet (or included in the supplement) is less effective.
For dogs and cats, the difference between brands can be very noticable -- often what happens is that a dog-owner starts giving her dog a glucosamine supplement from the pet-store, and this works well for a while, but as the dog ages it becomes less effective. We'll suggest they try the top-shelf 'Cosequin' brand and very often the dog's performance-levels will improve again, often better than it did when the original pet-store supplement was working at its best. Something of a pity, really, one wonders how well the dog would be doing if he'd been on the higher-quality supplement the whole time.
http://vm.cfsan.fda.gov/%7Edms/ds-savvy.html is a little blurb from the FDA about how to choose a good supplement. SusanK knows what she's talking about. The trouble is, sometimes, like in this case, reading the label might not help, because you don't know what you're reading for. Who knows all this stuff about glucosamine besides people like me, where it's our job to know? If you've got a doctor you can ask, ask her. And visit the websites of the manufactuers and find out what they say about their quality-controls, and if they do chemical analysis breakdowns for herbals, and bioavailability assays for everything.
