ok - did some more googling
sodium formaldehyde sulfoxylate/procaine hydrochloride - can both be a problem for any species - but in fairly high doses
lecithin is present in muscle tissue anyhow it seems
methylparaben can be mildly irritating to the skin so be sure you are subq with doseage
propylparaben - not a likely problem in rabbits - kidneys and liver get rid of it easily
Tween 40 - found nothing of use on this ingredient
Span 40 - seems to be a vitamin d complex ... lemme come back to this.. seems to be a good thing - helps with calcification issues - so perhaps is there to help counter other ingredients
sodium citrate - be cautious in using a young rabbit - it does affect fracture healing - which suggests it affects calcium ..
sodium carboxymethylcellulose - seems to cause issues in high amounts but as the last listed ingredient there may be very little of it present ...
I should ask is the intention to consume this rabbit eventually? some antibioitcs are prohibited for human consumption - even if they fdo the rabbit no harm
also consider age and condition of rabbits you want to use it on - old young pregnant and lactating does need more caution of course
I'm not a vet so can't (and won't) advise anyone on what to do however it seems that normal bicillan works fine on rabbits - I suppose on thing I would do is weight the pros and cons of taking a bit of a chance on this drug - what was I treating? how many rabbits could be harmed by it?
then if the balance is ok - I'd probably try it too