I'm due to start Acyclovir and from researching it seems most antivirals cause some degree of Mitochondrial Toxicity. Is there a way to avoid or negate these toxicity side effects?
The single best way to avoid mitochondrial toxicity from a direct-acting antiviral (DAA) is to simply choose a DAA that doesn't come with mitochondrial toxicity. Newer DAA's are tested early on in the development process for mitochondrial toxicity, so the newer DAA's generally don't have any mitochondrial toxicity at the established doses.
In your table it shows AZT and ddC, which are old HIV drugs with significant mitochondrial toxicity. For this reason, AZT and ddC are no longer prescribed by doctors. And for this reason, newer DAA's are always first tested for mitochondrial toxicity, often using multiple methods.
But your table also lists acyclovir, which is not known to cause significant mitochondrial toxicity at the established doses. There may be a theoretical risk of mitochondrial toxicity, but thanks to its very short half-life, it probably don't have much time to cause non-reversible damage. (Mitochondria can typically recover from minor, short-term damage.) Perhaps at much higher doses with more frequent dosing, you might see some significant toxicity from acyclovir.
But it probably couldn't hurt to use some mitochondrial support nutrients, such as B vitamins or glutathione precursors.
I hope this helps.