@Pompous Git - Re: Codeine
These days, over-the-counter* Lomotil (aka Co-phenotrope) does the same, it works wonders for the trots and fast, it has come to my aid on multiple occasions, especially when traveling. Lomotil has been around for many years and contains a cleaver combination of the reasonably powerful opiate diphenoxylate (the active ingredient) and a small amount of atropine.
Diphenoxylate, like laudanum/morphine and other opiates, works very effectively in slowing the intestines/stopping diarrhea but it's still an opiate, thus addictive. To overcome the problem of addiction (or being used as a substitute for morphine/heroin addicts), a precise amount atropine is added to the diphenoxylate. Taken in the correct dose, the Lomotil works wonders, but when it's taken in excess the atropine kicks in making the patient quite ill with nausea and tachycardia. Essentially, the addict cannot consume enough diphenoxylate for a 'high' before the atropine puts him out of action. This cleaver trick means ordinary non-addicted people aren't too inconvenienced when they need it.
BTW, Lomotil/diphenoxylate is much faster acting and of considerably shorter duration in its effect than that other anti-diarrhea drug loperamide (Imodium), 4-6h vs 24h. IMHO, Lomotil is a much better drug, Imodium takes far too long to kick in and often lasts much longer than necessary thus one ends up with constipation.
For years, when traveling to strange places, eating strange foods, diphenoxylate and the anti-nausea drug prochlorperazine; aka Stemetil, and the anti-tummy-bug drug metronidazole, aka Flagyl were and still are essential travel companions, in combination they often worked wonders.
* OTC depends where you live, sometimes it's script only, or script above a certain quantity,