Moriarty the Patriot: A Study in Quinine

This week on Moriarty the Patriot, the show’s elusive criminal consultant orchestrates yet another grand homicide for the sake of the lower class. The gardener Burton and his wife Michelle have just lost their sick child because of the Viscount of Belfor’s refusal to let him be treated. Upon hearing their story, Moriarty provides them a plan to kill the Viscount, one that turns his own heart condition against him rather than endangering the lives of Burton and Michelle. So as long as they played their roles correctly, Burton and Michelle would finally be freed from their grief and remorse.

Even though I enjoy Moriarty’s nefarious schemes to take down the nobles, this one takes a special place in my heart because it’s medical-related. It is not a coincidence nor a contrived plot point that grapefruit juice is introduced as the crux to “kill” the Viscount. There is actual science behind the complex relationship of quinine and grapefruits that is still being discussed today, so let’s take a quick dive into it.

What actually is quinine? 

As described in the anime, quinine is an anti-malarial drug. The compound is a natural extract from the bark of the cinchona tree in Peru, and has been in circulation since the Jesuit missionaries brought it back to Europe in 1636. However, by the 1800s, the bitter-tasting quinine became lauded as a wonder drug in tonic waters to help with irregular heart palpitations and muscle cramps. It also has an “isomer,” which is a different structure or orientation of the compound that may result in vastly different properties. This isomer is quinidine and is known to also be anti-malarial and treat irregular heart conditions better than quinine.

How does all this tie in with grapefruit juice?

In Moriarty the Patriot, the Viscount ingested both the quinine and the grapefruit juice during a moment of panic that caused his heart palpitations. As it turns out, grapefruit juice contains a component known as furanocoumarins. This chemical can block the CYP3A4 in your body, an enzyme that metabolizes many medications today. Medical practitioners generally advise against drinking grapefruit juice in conjunction with prescribed medication to prevent contraindications. Unfortunately, the Viscount had no knowledge of this and upon drinking the grapefruit juice, he eventually died from untreated cardiac arrest. 

However, research has proven that grapefruit juice does nothing to quinine. A study in New Zealand showed that healthy patients who ingested 600 mg of quinine sulfate and 200 mL of grapefruit juice did not suffer from any adverse side-effects (P. C. Ho et. al). Additional research well into the 21st century continued to prove that quinine and grapefruit juice showed no adverse signs of drug-interactions (Kane & Lipsky 2000), if not any drug-interactions at all. 

Meanwhile, studies with quinidine and grapefruit juice indicated severe side-effects. The American Journal of Medicine reported a case of a 31-year-old woman with QT syndrome dying of torsade de pointes due to an excessive intake of grapefruit juice and tonic water with quinidine (Hermans et. al 2003). But that’s not all. Even in healthy male volunteers, oral doses of quinidine and an intake of grapefruit juice led to a delayed response in heartbeats (Min et. al 2006), emphasizing the risk of taking both substances.

So, why quinine instead of quinidine in Moriarty the Patriot

It’s possible that the Viscount’s medication contained varying concentrations of quinidine and quinine. Chemical isolation processes to separate compounds were a relatively new concept in Victorian England, so refining quinine for public use may have been quite shoddy. At the same time, it must have also been a misnomer that quinidine is quinine and they were falsely advertised under the same name for the sake of profit. Consumers don’t care what the name of a drug is or its respective side-effects — as long as the drug has a similar name, it’s considered the same. People will do anything for a wonder drug. 

Was it realistic for Moriarty to know about grapefruit juice’s side-effect?

There is absolutely no way that Moriarty would’ve known that grapefruit juice had adverse side-effects on medicinal tonics and oral tablets. The first scientific experiment of grapefruit juice with medicine was recorded in the 1980s and later publicized by a New York Times article in 2006. However, to perpetuate the fact that Moriarty is a criminal genius and possesses academic knowledge far beyond the scope of Victorian England, creative licenses need to be taken to give him this insight and construct him as the series’ most formidable character. I have to applaud the writers for introducing such a semi-realistic and fascinating method of assassination outside of the typical poison or toxic fumes. 

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