var get's metabolized primarily outside of the liver, so it stresses the liver to a lesser degree than other orals. i think, ironically, anadrol is the next oral on the list of less harsh orals, even though drol seems to destroy most people with the other sides. on the other side of the coin, superdrol and m1t would be at the very top of the list liver toxic orals.
oral primo isn't methylated at all, so lacking a methyl group means it's not toxic to the liver, but also that the liver will destroy a significant portion of the drug. also, the fact that orally administered drugs have a lower bioavailability and that primo is inherently a less potent steroid, you need to take a ton of oral primo a day in order to see any benefit from it. considering that primo is also very expensive, and the most faked steroid, it makes it much less viable to run an oral primo cycle unless you are wealthy.
i would opt for primo-enanthate if i were to go the primo route, and only use oral primo if you wanted to see how you handled the drug (really no sides except hairloss and prostate hypertrophy in some people).