Deadly Grapefruit

part four

"Furanocoumarins!" Sherlock yelled, shocking John awake. Hours had passed and after exhausting every scientific test Sherlock could attempt in his kitchen, he moved to St. Bartholomew's Hospital to use their machines and equipment. It was now into the early hours of the morning and John had fallen asleep with his head resting on his hand at a counter to the side. Until, of course, he was woken up by Sherlock's screaming.

Groaning and squinting his tired eyes, John stretched his back and arms and checked his watch. "It's two thirty in the morning," he deflates. "Oh god, two thirty. Sherlock, it's two thirty in the bloody morning, what the hell is so important that you had to shout?"

"Furanocoumarins, John," Sherlock answers. John furrows his brows and heaves himself off his stool, coming to stand beside the detective. He doesn't try to hide his half-asleep confusion.

"I found grapefruit in Mr Rudkin's stomach," Sherlock began his explanation. "Furanocoumarins are chemicals within grapefruit. They inhibit an enzyme in the stomach called cytochrome P450 3A4. What cytochrome does is inactivate approximately half of any drug. Without the enzyme, every prescribed drug becomes twice as concentrated as the recommended dose."

John still looked confused, but Sherlock carries on, "Lestrade was right, the man's heart was perfectly healthy because he was taking verapamil for his high blood pressure."

"Okay? And? How does- hold on," John's tired mind caught up and registered what Sherlock had said. "So, by eating some grapefruit, it made his medication twice as strong?"

"He didn't eat it. He had Eggs Benedict for breakfast and there wasn't a side plate at the table. He drank it," Sherlock emphasised, thinking it obvious. John gave him a scowl. "The contents of his drinking glass, test came back with 100% grapefruit juice. I'd hazard a guess and say it was freshly squeezed that morning and we'll find the old grapefruits in the house's bin." Sherlock looked smug.

"So, he died of an overdose?" John asks.

"Not quite. He died of complete heart block, caused by an overdose." Sherlock reaches over and angles his laptop to show John the screen, displaying an article titled 'Prescription drugs and grapefruit a 'deadly mix''. "It's happened before."

"Huh," John mutters, raising his eyebrows at the article. "So, what now? We know how he died but we don't know who did it or why?"

"That all depends on what Lestrade has found out from Mr. Rudkin's staff," Sherlock replies, collecting his coat and turning to leave.