The untold story of 81 mg aspirin

Wersquore all used to prescriptions right Headache Take a single 500 mg tablet of Paracetamol Travellerrsquos diarrhoea Knock it out with 400 mg capsules of Norfloxacin twice a day for three days By any chance accidentally exposed to anthrax The doctor prescribes Doxycycline 100 mg capsule twice a day for 60 daysNotice something Theyrsquore all round numbers Sometimes you get a number ending in 5 like when a person has rheumatoid arthritis Then it would be 325 mg of sulfasalazine Note though that itrsquos still divisible by fiveIf you conclude that figuring out a drugrsquos dosage is an approximate science you would not be far off the mark A doctor will usually arrive at the best dosage for you by factoring in your age height body mass drug allergies and other medications you may be onThis might explain why after they put a stent into my heart some years ago and prescribed exactly 81 mg of aspirin daily I sat upAspirin generally regarded as a miracle drug is best known as a headachekiller but also as an antipyretic meaning it brings down fever One of its effects that cardiologists exploit is its ability to inhibit blood clotting by preventing platelets from sticking together It is normal for a person who has undergone any cardiac procedure or surgery to be placed on a lifelong daily regimen of aspirinExactly 81 mg of aspirinHow did they arrive at such an odd and precise number Logic says that they must have found 80 mg ineffective and 82 mg deadly But is that how pharmacists determine dosage milligram by milligramI took the question to the Internetrsquos idiot savant ChatGPT throwing in Claude AI and Googlersquos Gemini AI for good measure One piece of pharmaceutical propaganda that floated out was ldquoThe 81 mg dosage for aspirin as a blood thinner is not an arbitrary number but rather based on extensive clinical research and evaluation Specifically the 81 mg dosage was found to provide the optimal balance between efficacy and safety This dose was enough to inhibit platelet aggregation and prevent clot formation but it minimised the risk of excessive bleeding compared to higher dosesrdquoBullshit I thoughtChatGPT put on its reading glasses and pronounced that the prescription of 81 mg was based on ldquopharmacological principles and clinical evidencerdquo and that slight deviations from this might have different effectsGooglersquos Gemini AI told me to suck it up and not question science because the choice of 81 mg was based on ldquoa large amount of research datardquoSo I shut up But only for a whileThe truth behind 81 mg can be traced back to what the British and French loved to drink when the sun set a nice wellaged whiskey Specifically it goes back to the grain most popular among the Scots and the Irish in the Middle Ages for brewing whiskey barleycorn They were so nuts about barleycorn grains that apothecariesmdashor pharmacists in plain Englishmdashbased their system of weights and measures on itThe basic unit of weight was a single grain of barleycorn unsurprisingly called a grain and abbreviated to gr In modern terms a grain would be 648 gm In England 20 grains equalled one scruple and not a reflection on the moral standards of the doctor or the patientThe French never a nation to follow the British meekly decided that in their country 24 grains not 20 would be one scrupleIn both countries though three scruples made a dram eight drams made an ounce and 12 ounces thatrsquos correct not 16 made a poundQuite overwhelmed by their own cleverness the British decided that the whiskey grain could also be used to define lengths They lined up three mediumsized barleycorn grains end to end and thought inch might be a nice name for it Fortunately the barleycorn inch was more or less equal to the inch as we know it todayIn 1790 French scientists upset the applecart by coming up with a new measurement protocol the metric system The kilogram was defined as the mass of one cubic decimeter of water at four degrees Celsius Pretty soon England went metric tooHowever the apothecary system refused to go away like a stubborn stain After repeated outcries from physicians both systems were deemed legal in Britain till 1898 when the barleycornbased system was kicked out and the metric system became the law of the landAmerica too allowed the two systems to run in parallel though even as late as the turn of the century only six per cent of American prescriptions were written in the metric systemIn the thick of this merry dance of numbers and units three medicines have been prescribed since the Middle Ages always in grains aspirin codeine and morphine The standard adult aspirin dose was five grains Its metric equivalent 324 mg rounded off to 325 remains the prescribed dose for analgesia today Lowdose aspirin was a quarter of the standard dose or 125 grains and has remained unchanged until nowDo the math A quarter of 324 mg is 81 mgYou can reach C Y Gopinath at cygopigmailcomSend your feedback to mailbagmiddaycomThe views expressed in this column are the individualrsquos and donrsquot represent those of the paper