a ‘reversible cholinesterase inhibitor’ because the enzyme can regain its function. There is an 81 per centrecovery of AChE after two hours and 100 per cent within 24 hours. By contrast, other AChE-inhibiting compounds, such as the organophosphate nerve gas sarin, bind permanently; eserine can therefore prevent sarin poisoning, if it is administered at the appropriate time, by temporarily blocking AChE until the body has had a chance to eliminate most of the sarin. Eserine is also more soluble in fats than many other AChE inhibitors, so is able to cross the blood-brain barrier to prevent damage to the brain in the event of poisoning by sarin or similar compounds.
As well as its use in cases of atropine and sarin poisoning, eserine was once suggested as a treatment for tetanus, 51 and as an antidote for strychnine and curare poisoning. The most successful of these treatments was with curare and the drugs derived from it. Curare is the plant-derived arrow poison Agatha Christie’s pharmacist Mr P. carried around in his pocket (see page here ), and along with its related compounds, it has found wide uses in medicine. These compounds cause the relaxation of muscles by blocking acetylcholine receptors, which is often very useful during surgical procedures.
The similarity between curare poisoning and an inherited condition, myasthenia gravis, led the physician Mary Broadfoot Walker (1888–1974) to test eserine on one of her patients. Myasthenia gravis produces fluctuating muscle weakness, with muscles becoming weaker with increased activity but improving after periods of rest. Symptoms can develop suddenly, and are intermittent. The muscles that control eye movements, facial expressions, chewing and swallowing are usually the worst affected, but movement of the limbs and the muscles that control breathing can also undergo periods of weakness. When Walker conducted her experiments in 1934, the cause of myasthenia was not known, but one theory heldthat patients were not producing enough acetylcholine to act on the receptors in the muscles. Injections of eserine produced a dramatic, though temporary, improvement in two patients, indicating that although the individuals were producing acetylcholine, it was failing to act on the muscles. Further studies have shown that myasthenia gravis patients produce antibodies circulating in the body that block acetylcholine receptors. Today the condition is treated by a combination of immunosuppressant drugs and anticholinesterases (such as neostigmine) that prevent the breakdown of acetylcholine and allow it to act on the receptors for a longer period of time.
Some real-life cases
Since the missionaries put a stop to ordeal trials in West Africa, deliberate eserine poisonings have been rare outside of Agatha Christie’s novels, which makes you wonder where she found her inspiration. The poison itself is difficult to obtain, and even if someone had a prescription for it, consuming a whole bottle would be unlikely to be fatal, though it might make them very ill. In 1968 a biochemistry student attempted suicide by swallowing 1g of eserine salicylate, which he had stolen from a laboratory. He developed severe abdominal pains after ten minutes, followed by terrifying hallucinations that induced him to seek help. Although atropine was administered it made his condition worse, as he did not display the characteristic slow heartbeat, and atropine only increased his heart rate. Atropine is not a true antidote for eserine poisoning because the compounds act on different sites in the body. He was subsequently given aldoximes, which reactivated the AChE enzymes that were inhibited by the eserine in his body. He went on to make a full recovery.
I have only managed to find one other case of deliberate eserine poisoning, but it is not clear who did the actual deed. The case was reported in Austria, long after the publication of Crooked House and Curtain . A man of around 50 years of age was
As well as its use in cases of atropine and sarin poisoning, eserine was once suggested as a treatment for tetanus, 51 and as an antidote for strychnine and curare poisoning. The most successful of these treatments was with curare and the drugs derived from it. Curare is the plant-derived arrow poison Agatha Christie’s pharmacist Mr P. carried around in his pocket (see page here ), and along with its related compounds, it has found wide uses in medicine. These compounds cause the relaxation of muscles by blocking acetylcholine receptors, which is often very useful during surgical procedures.
The similarity between curare poisoning and an inherited condition, myasthenia gravis, led the physician Mary Broadfoot Walker (1888–1974) to test eserine on one of her patients. Myasthenia gravis produces fluctuating muscle weakness, with muscles becoming weaker with increased activity but improving after periods of rest. Symptoms can develop suddenly, and are intermittent. The muscles that control eye movements, facial expressions, chewing and swallowing are usually the worst affected, but movement of the limbs and the muscles that control breathing can also undergo periods of weakness. When Walker conducted her experiments in 1934, the cause of myasthenia was not known, but one theory heldthat patients were not producing enough acetylcholine to act on the receptors in the muscles. Injections of eserine produced a dramatic, though temporary, improvement in two patients, indicating that although the individuals were producing acetylcholine, it was failing to act on the muscles. Further studies have shown that myasthenia gravis patients produce antibodies circulating in the body that block acetylcholine receptors. Today the condition is treated by a combination of immunosuppressant drugs and anticholinesterases (such as neostigmine) that prevent the breakdown of acetylcholine and allow it to act on the receptors for a longer period of time.
Some real-life cases
Since the missionaries put a stop to ordeal trials in West Africa, deliberate eserine poisonings have been rare outside of Agatha Christie’s novels, which makes you wonder where she found her inspiration. The poison itself is difficult to obtain, and even if someone had a prescription for it, consuming a whole bottle would be unlikely to be fatal, though it might make them very ill. In 1968 a biochemistry student attempted suicide by swallowing 1g of eserine salicylate, which he had stolen from a laboratory. He developed severe abdominal pains after ten minutes, followed by terrifying hallucinations that induced him to seek help. Although atropine was administered it made his condition worse, as he did not display the characteristic slow heartbeat, and atropine only increased his heart rate. Atropine is not a true antidote for eserine poisoning because the compounds act on different sites in the body. He was subsequently given aldoximes, which reactivated the AChE enzymes that were inhibited by the eserine in his body. He went on to make a full recovery.
I have only managed to find one other case of deliberate eserine poisoning, but it is not clear who did the actual deed. The case was reported in Austria, long after the publication of Crooked House and Curtain . A man of around 50 years of age was
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