I have been prescribed for my own ringworm piggies: 0.05 ml per every 100g of body weight. That makes 0.5 ml for 1 kilo once a day.
The concentration on the leaflet with the itrafungol says that it is a concentration of 10mg of itraconazole (the actve ingredient) for each ml of the solution. Please check that. If necessary, call the clinic and ask them to look up the concentration of their product for you. Perhaps your vet has upped the dosage because of the severity of the ringworm in some places?
Not all piggies in a group will necessarily develop acute ringworm but they can act as carriers of spores and can cause a new break out; I had ringworm carried in once by a new piggy that was not affected but had gone through quarantine with their affected family.
The itrafungol will make sure that all ringworm spores directly on the body (acute or latent) are killed off; please use it on all piggies living together.
Additionally you will have to bathe them all at the same time as you conduct a thorough deep clean with F10 disinfectant on the cage and any hard furnishing and a 60 C/140 F wash on any fabrics in contact with ringworm. This is to ensure that no spores sitting loosely in the coat can be carried across and cause a new outbreak.
Be aware that you and your own clothing can act as the transmissor of shed spores so you need to wash any fabric in direct contact at a higher temperature and wash/disinfect your hands/arms between handling each piggy; be aware that the spores often cause an infection on your neck or face in the areas you touch without noticing.
Always start with the unaffected piggies in order to minimise the risk of transmission you yourself pose. I did cause a new outbreak once this way a good decade ago before itrafungol came on scene and I also had carried that batch of ringworm into my group by a piggy that had been with ringworm piggies but had not been affected. Our advice is based on lessons learned the hard way.
Please take the time to read the very detailed hygiene advice in our ringworm guide link below very carefully. It does really work when you thoroughly close off any potential transmission angles. We have learned our tips the hard way but have seen since often enough that our advice does do the trick. The problem with ringworm is its high contagion and the fact that the invisibly tiny spores can stay live for around 2 years and can cause a new outbreak or transmit to humans and other pets at any time if those spores are passed on directly or indirectly. It can really turn into a long running saga.
Topical treatments do work but they do not necessarily address the problem of the spore shedding; especially just creaming. in those cases secondary ringworm patches from picked up spores usually appear all over the body.
However, in my last outbreak 5 years ago (in a guinea pig that had been a vet surrender because of a very advanced case of ringworm due to incorrect treatment) I was able to keep the outbreak confined to the one acutely affected piggy with a single ringworm spot in a room with 31 piggies at the piggies; I also treated their companion so there was no risk that they would ever develop acute symptoms and prolong treatment and quarantine.
I deep cleaned my whole room from top to bottom while my affected pair was in quarantine outside in my hospital cage in an area I would wipe down very easily until 2 weeks after the end of treatment with itrafungal and after one last bath. It was a pain but it did the trick. Ringworm is something you really want to throw the hygiene kitchen sink at. I've never had any more ringworm issues since then in my piggies and my ringworm boy lived for another 4 years totally free of it.
Please never underestimate the spores; the big blind spot with oral treatment are the spores in the coat that have been picked up directly from an acute mate, from the bedding or your clothing or that are left over from an acute outbreak but that are not in direct contact with the skin and can therefore not be reached by the medication. This is a transmission angle that is all too often overlooked. All it takes is just a single spore to restart it all again. At least one bath at the end of any oral treatment in order to wash any spores off is necessary.
Here is the guide link:
Ringworm: Hygiene, Care And Pictures
All the best. You
can get on top of it.