Over 75,673 people died from opioid-related overdoses the year before last in the US alone. And that's not even counting non-opioid related overdoses. Compare that with the 40,000 something suicide deaths alone. F kills people like flies, but it's just the tip of the iceberg. More potent analogues, such as some of the Etazines (x10,000 more powerful than Morphine) are cheap and easily sourced on the DN. Fent is also on the DN, vendors just label it "White China" to get around the DN market fent ban. Search around diligently enough, and you'll find it. Where there's a will, you'll find the way.
I'm CBTing with a concoction of barbiturates, RC Opioids and SN with Baclofen (antispasmodic) and an antianemic in some remote, uninhabited part of a forest.
Because of barbiturates' dangerous safety profile and respiratory arresting properties, benzodiazepines were hence commercialized as a safer replacement. Barbiturates comprise the de facto lethal injection drugs, specifically phentobanatroll, which is easily sourced from the DN. Barbiturates combined with opioids are a near-guaranteed lethal concoction, by any measure. Each critically inhibits respiratory suppression independently, and when combined, these effects are multiplicatively compounded.
Encapsulation in eccentric coated capsules would enable the drugs to pass through the stomach in-tact, and begin dissolving past the duodenum in the lower intestine, where regurgitation is no longer an object.
Profonol, is another one. A powerful lethal anesthetic. The vials are only used in hospitals under the extreme care of anesthesiologists because of its lethal dose threshold. Profonol is the drug that killed Michael Jackson, which is also sourcable if you know where to look.
Antianemics only inhibit regurgitation in part. Antispasmodics inhibit the ephosphical contractions which are essential for vomiting. If your esophageal muscles can't contract, you can't vomit.