you can also get spot on droncit ... i also thought the droncit injection didnt last as long as previously stated so away to look it up now. (ps droncit inj has been on the go for as long as i can remember and i'd also say it would work within the 24-48 period aswell)
Droncit® Spot-On
Droncit® Spot-On (20 mg praziquantel) is a tapeworm treatment for cats applied directly to the skin on the back of the neck.
The application to the skin makes it ideal for use in fractious cats, helping avoid having a fight on your hands. It is also for hunting cats which require frequent treatment. It is effective against all the common tapeworms found in cats in the UK, and also the fox tapeworm that is prevalent in mainland Europe.