Hmm...the active ingredient is pyrantel pamoate but I see here it might be called something different in different parts of the world...
https://www.drugs.com/international/pyrantel.html
Panacur (fenbendazole, safe guard) is an excellent product and even kills tapeworm but yes, it is not appropriate for use until the pups are six weeks. Did your vet have a reccomendarion for a dewormer for pre six weeks?