Generally speaking, OD with antidepressants is not worth it at all. Most modern antidepressants have been made to at least hamper suicidal patients to use them.
That said, nortriptyline belong into trycyclic antidepressants which have short therapy index. According into Olson's Poisoning & Drug Overdose, doses of less than 10 times the therapeutic daily dose may produce severe intoxication. Since nortryptiline have therapeutic dose of 75–150 mg/kg, we can rough the number up into 750-1500 mg/kg. But in general, ingestion of 10–20 mg/kg of some tricyclic antidepressants is potentially life-threatening.
What are the symptoms? Here's how it goes:
A. Cardiovascular effects. Several mechanisms contribute to cardiovascular toxicity:
1. Anticholinergic effects and inhibition of neuronal reuptake of catecholamines result in tachycardia and mild hypertension.
2. Peripheral alpha-adrenergic blockade causes vasodilation and contributes to hypotension.
3. Membrane-depressant (quinidine-like) effects cause myocardial depression and cardiac conduction disturbances by inhibition of the fast sodium channel that initiates the cardiac cell action potential. Metabolic or respiratory acidosis may contribute to cardiotoxicity by further inhibiting the fast sodium channel.
B. Central nervous system effects. These effects result in part from anticholinergic toxicity (eg, sedation and coma), but seizures are probably a result of inhibition of reuptake of norepinephrine or serotonin in the brain or other central effects.
Tldr: It usually affects CNS and cardiovascular with dysfunction of the heart and coma if they're led long enough.
Here's a case report of this if you're interested:
Xanax (alprazolam) works extremely fast, around 15-30 minutes after ingesting it:
So yeah maybe you could try to experiment yourself. Imo there's a lot to prepare in terms of medication:
1. Know how your onset time of Xanax to be the more prepared. I'd suggest having a timer from the start of you drinking it up to the time you experience its effects. Might be more better if you record yourself from the start instead of a timer since you may experience drowsiness or outright sleeping after you experience Xanax.
2. Try which OTC painkiller is the best option for you in terms of availability and its effect. Usually OTC painkiller is weaker than prescription one. But also I'm from Indonesia so I can't really judge your medication availabiliy there.
3. Know the onset of your chosen painkiller. Do the same as to Xanax, but maybe test its painkilling effect by sh.
The problem is that imo there's a lot to prepare on hanging yourself. This maybe really OOT for this one, but I found a good topic of full suspension (and hanging in general) made by people in SaSu here. Here's the link:
Remember, if you plan to ctb, make sure to at least plan this as thorough as possible with the resource you have. Be quick and be painless on your ctb so that you don't regret it in the future.
