You can levamisole in a measured amount from Charles ;
http://www.inkmkr.com/Fish/ItemsForSale.html
Here is the directions for use ,note Charles uses a larger dose then what most follow on the loach pages that actually use Charles as a source of info in their bibliography ..
http://www.inkmkr.com/Fish/CamallanusTreatment/
When I used levamisole years back on swordtails I got infected from a breeder I used the 1 gram per 20g of water without any problems ..
He also sells flubendazole ..