Ok, so Arranda or other MX vet brand, prob at concentration of 60-65mg/ml, for about 6-6.5g total. It's kind of a borderline amount, a little less than half what is currently used at Dignitas etc. I'd recommend looking into supplementing with phenytoin sodium (e.g. Dilantin) (2-3g), mixed into water consumed right before N (helps induce cardiac failure), and following up with a few glasses of a strong liquor of your choice (neat or on the rocks, no fancy cocktails). With that amount I would also strongly advise minimum 24h (longer even better) alone and uninterrupted to account for potential longer time to death.
Btw D previously sold a stronger concentration closer to 20g/bottle prior to the 6g concentration, hence my asking brand/concentration. If you have that stronger variant you can disregard the phenytoin and go lighter on or even skip the alcohol.