No. This is a myth that has been passed along by drug addicts that have been trying to find unique ways of getting the necessary ingredients for illegal drugs like methamphetamine, also commonly known as crystal meth.
Medicated salt licks contain minerals and vitamins that are needed for a cow's normal productivity that are not found in or contain very small amounts in feed or in the grass/soil that are not enough to satisfy a cow's macromineral/micromineral needs. Such salt licks or loose salt mixes are not used on just cows, they are also great for young growing cattle like feeder/stocker steers/heifers, replacement heifers, young bulls, and mature bulls that have just come off of breeding season and need to gain some weight back that was lost during the time he was needed to chase after those frisky, horny cows. As for ephedrine salt licks, they don't exist.
They do not. This is a myth that has been spread around by meth-users in making recipes from certain things in their attempts and making the illegal narcotic crystal methamphetamine.
They are not and never have been. Ephedrine is not found in medicated salt blocks.
Nowhere. These type of blocks do not exist.
There are no salt or mineral nor medicated mineral blocks that contain any form of ephedrine in them. Sick animals are treated by antibiotics via injection, not by just giving them a "medicated" salt block.
None. No such salt block or loose mineral mix exists.
None because no such block exists.
None. There is no such thing as a medicated salt block, especially one that contains ephedrine that you can use to make crystal meth!!
None. No such salt block, medicated block nor loose mineral mix exists.
Nowhere because no such salt or mineral block exists.
There really is no such salt block or mineral mix. You can check with your veterinarian or those companies that make livestock salt blocks but it's highly likely you will not find such an ingredient in salt licks for cattle.
None. No salt licks, mineral blocks, medicated feed or any of that sort have ephedrine in them. This is a myth that has been tested and busted by various scientists that have tried to extract ephedrine from various animal-feed and chicken litter sources. Please see the related question below for more info.
Safe-Guard makes a medicated dewormer salt block, and Bovatec makes a medicated block made to increase average daily gain of pasture stocker, slaughter, feeder cattle and beef/dairy replacement heifers. However, no other manufacturer makes any type of medicated salt block that contains the mythical ephedrine that is claimed to be extracted and used for crystal meth.
NaCl. That's it: just plain table salt. And there really is no such thing as a "medicated" salt block.