Panacur is not licensed for use in Poultry in the UK. It is a wormer that is commonly used for cats and dogs but is a broad spectrum wormer that many vets will prescribe for poultry, often because they don't stock Flubenvet.
If you take your chickens to the vets for worming they will probably be given Panacur.
Used to treat: Large roundworm, caecal worm, gapeworm, hairworm and gizzard worm in poultry and the Taenia species of tapeworm.
Dosage: Varies according to the vet's advice. Usually between 10mg and 50mg per Kg of weight. Repeated 7 to 10 days later.
Active ingredient: Fenbendazole.
Egg withdrawal for chickens: Intervet (who make Panacur) advised 7 days following the last day of treatment.
Slaughtering for meat for human consumption: 7 days after the last treatment
Length of treatment: 7 to 10 days (dosage is repeated after 7 to 10 days).
Storage: In tightly closed original container below 25ºC and out of reach of children.
Further information can be found on NOAH Compendium of Animal Medicines
The advice given here is that of the authors and should not be considered as professional advice. Where there is conflicting information, you should always follow the advice of your vet.