Hello Monique
Chloroquine isn't used much in the USA or in the UK, I think mainly because it has the reputation of a greater risk of eye damage. Actually I haven't heard of anybody in the UK taking chloroquine, brand name Aralen.
Since they are very similar it is unlikely that someone who doesn't tolerate Plaquenil would be OK with Aralen, certainly not as far as eye toxicity goes. there is an alternative antimalarial which is different enough to be a highly acceptable option, called Mepacrine in the UK & Quinacrine in the USA.
It was used for anti malarial prophylaxis known as Atabrine, but Plaquenil replaced it and it has to be obtained from a compounding pharmacist
As it happens I take chloroquine instead of Plaquenil as being more potent, in combination with the Mepacrine. A very effective combination in certain cases. I take 500mgs a day with 100 Mepacrine.
My USA doctor said that chloroquine's reputation for eye toxicity was unmerited and dates from the time when it was used in much higher doses.
The chloroquine was very cheap in the USA compared with Plaquenil and I guess that might be the case in the UK. I don't know because I am old enough to get my meds free

I guess I wouldn't know anyway unless I asked since I don't think the price is usually on packaging here we just pay the prescription cost.
Cheers
Clare