did you crush or chew the albendazone? This is important, as albendazone is poorly absorbed in the gut.It could be that the acid in grapefruit and other foods dissolved the tablets, increasing absorption. The more research i do on my own, the more i appreciate ICU's posts, as credible, peer reviewed literature confirms all that he/she has posted. She did all the hard work for us and gave us the necessary heads up :) .
Also, fat is also needed for bioavailability of albendazone. You said you hadn't taken it with fat before, so that might be another big factor that lead to its failure in treating you.
Also, you forget to answer me about if you were constipated or not.
"For humans, several strategies were studied to enhance albendazole bioavailability. When combined with a fatty meal, administration of albendazole sulfoxide (ABZSX) increased the maximum concentration of drug in serum (Cmax) 4.5- to 9-fold"