A cup of strychnine can be nice

Caffeine is a molecularly similar to strychnine and acts upon the same neural receptors, which cause the latter's lethality. Oddly this makes them both in low doses stimulates.

Strychnine was taken to revise for exams, aid endurance in Olympic Marathons and prescribed by doctor as a tonic. It was the Victorian caffeine and high-energy tonic. 

That is not odd: strychnine and caffeine are similar molecules. They both block glycine receptors. The difference apart from strength–caffeine is much weaker is that caffeine also blocks another group of receptors – those for adenosine. But similarity of its stimulant effects with strychnine suggests that its stimulant actions might also be due to its actions upon glycine receptors.

Strychnine was an ingrediant of tonics such as Easton's tablets, Wampole's Preparation and Fellows’s Syrup of Hypophosphites. As recently as 1981 Brent Smith found that 41 commerical products in the US were available for human consumption including proprietary analgesics, digestive aids, cold remedies, cathartics, tonics, vitamins, stimulants, and sedatives. One of the tonics taken by Hitler contained strychnine. As Ronald McGarry and Pamela McGarry note

Another commonly prescribed medication, nux vomica (essence of bachelor button), contained strychnine, a highly toxic central nervous system stimulant. Given that “the bitters”was prescribed for a multitude of ailments, one wonders how many cases of strychnine poisoning there were.

Research by the famous psychologist Karl Lashley in 1917 found it enhanced the training done by rats in mazes. Medical students used it as a pick me up while revising with occasional problems as one Leondard Sandall, recalled in 1896 in a letter to the The Lancet.

Three years ago I was reading for an examination, and feeling " run down" I took 10 minims of strychnia solution (B.P.) with the same quantity of dilute phosphoric acid well diluted twice a day. On the second day of taking it, towards the evening, I felt a tightness in the "facial muscles " and a peculiar metallic taste in the mouth. There was great uneasiness and restlessness, and I felt a desire to walk about and do something rather than sit still and read. I lay on the bed and the calf muscles began to stiffen and’ jerk. My toes drew up under my feet, and as I moved or turned my head flashes of light kept darting across my eyes.. I then knew something serious was developing, so I crawled off the bed and scrambled to a case in my room and got out (fortunately) the bromide of potassium and the chloral. I had no confidence or courage to weigh them, so I guessed the quantity-about 30 gr. bromide of potassium and 10 gr. chloral-put them in a tumbler with some water, and drank it off. My whole body was in a cold sweat, with anginous attacks in the precordial region, and a feeling of "going off." I did not call for medical aid, as I thought the symptoms declining. I felt better, but my lower limbs. were as cold as ice and the calf muscles kept tense and, jerking. There was no opisthotonos, only a slight stiffness at the back of the neck. Half an hour later, as I could judge, I took the same quantity of bromide of potassium and chloral, and a little time after I lost consciousness and fell into a " profound sleep," awaking in the morning with no unpleasant symptoms, no headache, &c., but a desire " to be on the move " and a slight feeling of stiffness in the jaw. These worked off during the day. 28 March 1896. "AN OVERDOSE OF STRYCHNINE." The Lancet, 147(3787):887.

The mention of bromide is interesting because in Agatha Christie's first novel, The Mysterious Affair at Styles, the poisoning happens by the addition of bromide to a normally safe strychnine containing medicine to precipitate  to the bottom of a bottle where they get taken in a single, lethal dose.The medical student presumably took it to precipitate in the strychnine in his gut to stop further absorption.

It was one of the original performance enhancing sport’s drugs. At the 1904 Olympic Marathon, the US runner Thomas Hicks after 30 kilometer his manager following in a car administered 1/60th grain (approximately 1 mg) of sulphate of strychnine and repeated this a few kilometers later when Hicks tried to lie down. He finished the race in first place and then collapsed.

Caffeine and strychine molecules
caffeine strychnine

Duan L, Yang J, Slaughter MM. Caffeine inhibition of ionotropic glycine receptors. J Physiol. 2009 Aug 15;587(Pt 16):4063-75.

Doyle D. Adolf Hitler's medical care. J R Coll Physicians Edinb. 2005 Feb;35(1):75-82.

McGarry RC, McGarry P. Please pass the strychnine: the art of Victorian pharmacy. CMAJ. 1999 Dec 14;161(12):1556-8.

Pain S. Marathon madness. New Scientist. 7 August 2004. 46–7.

Lashley KS (1917) The effect of strychnine and caffeine upon rate of learning. Psychobiology 1:141–170

Smith BA. Strychnine poisoning. J Emerg Med. 1990 May-Jun;8(3):321-5. Jackson G, Diggle G. Strychnine-containing tonics. Br Med J. 1973 Apr 21;2(5859):176-7.