There is a safety margin for giving too much of albendazole, meaning that if a little too much over the correct dose is given, there won't be adverse effects.
https://en.wikipedia.org/wiki/Albendazole"Because of its low solubility, albendazole often cannot be absorbed in high enough quantities to be toxic.
[30] The oral LD50 of albendazole in rats was found to be 2,500 mg/kg.
[22] It takes 20 times the normal dose to kill a sheep, and 30 times the normal dose to kill cattle.
[1] Overdose affects the liver, testicles, and GI tract the most. It can manifest with lethargy, loss of appetite, vomiting, diarrhea, intestinal cramps, dizziness, convulsions, and sleepiness. There is no specified antidote.
[26]"
You'll want to keep a close eye on your rabbit to make sure he keeps eating and drinking normally. If he stops eating, then you may need to do assisted feedings.