Strychnine poisoning is poisoning induced by strychnine. It can be fatal to humans and other animals and can occur by inhalation, swallowing or absorption through eyes or mouth. It produces some of the most dramatic and painful symptoms of any known toxic reaction, making it quite noticeable and a common choice for assassinations and poison attacks. For this reason, strychnine poisoning is often portrayed in literature and film, such as the murder mysteries written by Agatha Christie. The probable lethal oral dose in humans is 1.5 to 2 mg/kg. Similarly, the median lethal dose for dogs, cats, and rats ranges from 0.5 to 2.35 mg/kg.
Presentation in humans Ten to twenty minutes after exposure, the body's muscles begin to spasm, starting with the head and neck in the form of trismus and risus sardonicus. The spasms then spread to every muscle in the body, with nearly continuous convulsions, and get worse at the slightest stimulus. The convulsions progress, increasing in intensity and frequency until the backbone arches continually. Convulsions lead to lactic acidosis, hyperthermia and rhabdomyolysis. These are followed by postictal depression. Death comes from asphyxiation caused by paralysis of the neural pathways that control breathing, or by exhaustion from the convulsions. The subject usually dies within two to three hours after exposure. One medical student in 1896 described the experience in a letter to 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. [30 grains, about 2 grams] 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 that the symptoms were declining. I felt better, but my lower limbs were as cold as ice, and the calf muscles kept tense and were 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, 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.
Treatment There is no antidote for strychnine poisoning. Strychnine poisoning demands aggressive management with early control of muscle spasms, intubation for loss of airway control, toxin removal (decontamination), intravenous hydration and potentially active cooling efforts in the context of hyperthermia as well as hemodialysis in kidney failure (strychnine has not been shown to be removed by hemodialysis). Treatment involves oral administration of activated charcoal, which adsorbs strychnine within the digestive tract; unabsorbed strychnine is removed from the stomach by gastric lavage, along with tannic acid or potassium permanganate solutions to oxidize strychnine.
Activated charcoal Activated charcoal is a substance that can bind to certain toxins in the digestive tract and prevent their absorption into the bloodstream. The effectiveness of this treatment, as well as how long it is effective after ingestion, are subject to debate. According to one source, activated charcoal is only effective within one hour of poison being ingested, although the source does not regard strychnine specifically. Other sources specific to strychnine state that activated charcoal may be used after one hour of ingestion, depending on dose and type of strychnine-containing product. Therefore, other treatment options are generally favoured over activated charcoal. The use of activated charcoal is considered dangerous in patients with tenuous airways or altered mental states.
Other treatments Most other treatment options focus on controlling the convulsions that arise from strychnine poisoning. These treatments involve keeping the patient in a quiet and darkened room, anticonvulsants such as phenobarbital or diazepam, muscle relaxants such as dantrolene, barbiturates and propofol, and chloroform or heavy doses of chloral, bromide, urethane or amyl nitrite. If a poisoned person is able to survive for 6 to 12 hours subsequent to initial dose, they have a good prognosis. The sine qua non of strychnine toxicity is the "awake" seizure, in which tonic-clonic activity occurs but the patient is alert and oriented throughout and afterwards. Accordingly, George Harley (1829–1896) showed in 1850 that curare (wourali) was effective for the treatment of tetanus and strychnine poisoning.
Detection in biological specimens Strychnine is easily quantitated in body fluids and tissues using instrumental methods in order to confirm a diagnosis of poisoning in hospitalized victims or to assist in the forensic investigation of a case of fatal overdosage. The concentrations in blood or urine of those with symptoms are often in the 1–30 mg/L range.
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