For many years doctors have argued about the preventative effects of low dose acetylsalicylic acid or aspirin. With the possibility of Covid-19 and an association with stroke in young and middle-aged adults, the possible prophylactic effect may be reviewed.
History of aspirin
Aspirin is one of the most widely used medications globally, with an estimated 40,000 tonnes (44,000 tons- about 100 Billion tablets) consumed each year.
Medicines made from the Willow tree and other salicylate rich plants appear from earlier than 3000 BC as well as ancient Egypt. Hippocrates referred to their use of salicylic tea to reduce fevers around 400 BC and were part of the pharmacopoeia of Western medicine in Greece and in the middle ages.
Willow bark extract became recognized for its specific effects on fever, pain and inflammation in the mid-eighteenth century and by the 19th century pharmacists were experimenting with and prescribing a variety of chemicals related to salicylic acid, the active part of the Willow extract.
In 1853, chemist produce acetylsalicylic acid for the first time and in the second half of the century, other academic chemists established the compound’s chemical structure and devised more efficient methods of synthesis.
In 1897, scientists at the German drug and dye firm, Bayer began investigating acetylsalicylic acid as a less-irritating replacement for standard common salicylate medicines and identified a new way to synthesize it and by 1899, Bayer had named this drug Aspirin.
Although the word Aspirin was Bayer’s brand name, their rights to the trademark were lost or sold in many countries.
Aspirin’s popularity grew over the first half of the twentieth century leading to fierce competition, but its popularity declined after the development of acetaminophen (paracetamol) 1956 and Ibuprofen in 1962.
From the 1960s through the 80s Dr. (Later Sir) John Vane and others discovered the basic mechanism of aspirin’s effects established aspirin’s efficacy as an anti-clotting agent that reduces the risk of clotting diseases.
Aspirin and the Prevention of Heart Attacks
The initial large studies on the use of low-dose aspirin to prevent heart attacks that were published in the 1970s and 1980s.
Aspirin sales revived considerably in the last decades of the twentieth century and remain strong in the twenty-first with widespread use as a preventive treatment for heart attacks and strokes. It is also believed to play a role in the possible prevention of colorectal cancer.
The action of aspirin
Aspirin’s effect on homeostasis is well-known. Low-dose aspirin (acetylsalicylic acid, 81 mg) inhibits the enzyme Cox-1, which produces thromboxane A-2, necessary for platelet aggregation (the ‘plug effect of haemostasis).
The primary effect of aspirin as an anticoagulant is thought to involve platelet function; however, aspirin is also an anti-inflammatory, less clear however are other methods by which aspirin acts as an anticoagulant.
Studies of microvascular injury models have demonstrated that aspirin at a daily dose of 30 mg administered for one-week decreased thrombin formation in healthy patients.
Researchers suggested that there is enough evidence to conclude that aspirin affects blood coagulation on many levels, not simply platelet function.
Aspirin may reduce thrombin formation and subsequently affect fibrin production. It may also affect acetylate fibrinogen, resulting in increased clot permeability and lysis, according to the researchers.
As well as the clotting mechanism, platelet function is also highly variable, so it is not surprising that differential protective effects of aspirin are observed over the entire population.
It must be remembered that serious bleeding may occur with excessive doses/overdose. Also in cases where other blood thinners are used.
Aspirin and its preventative effects on heart attack and stroke.
Aspirin is an important part of the treatment of those who have had a heart attack, but generally not recommended for routine use by people with no other health problems, including those over the age of 70.
Positional papers in the US for 2016, recommend initiating low-dose aspirin use for the primary prevention of cardiovascular disease and colon cancer in adults aged 50 to 59 years who have a 10% or greater 10-year cardio vascular disease (CVD) risk, are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years.
Aspirin and those at lower risk.
In those with no previous history of heart disease, aspirin decreases the risk of a non-fatal myocardial infarction but increases the risk of bleeding and does not change the overall risk of death. Specifically, over 5 years it decreased the risk of a cardiovascular event by 1 in 265 and increased the risk of bleeding by 1 in 210.
Aspirin appears to offer little benefit to those at lower risk of heart attack or stroke—for instance, those without a history of these events or with pre-existing disease. studies recommend aspirin on a case-by-case basis, while others have suggested the risks of other events, such as gastrointestinal bleeding, were enough to outweigh any potential benefit.
Some therefore recommend against its use for that purpose.
Aspirin’s possible use during Covid-19
As an anti-inflammatory and pain killer, it has been used for years for colds and flu. In the case of Covid-19, where a viral infection is involved, antibiotics are only useful in secondary infection. Initially treatment may be symptomatic as is post treatment recovery.
There have been reports regarding the possible causation of ischaemic (obstructive) stroke from the Covid-19 virus. Physicians may recommend aspirin for those with the active disease – your physician should be consulted first.
Clearly at times of pandemic outbreak such as this it is difficult to take a totally objective view as there is being learned as time passes and patients are treated. It is not to be considered a treatment for Covid-19.
The consideration of Aspirin’s possible use during Covid-19
This however appears as a possible adjunctive approach to be reviewed. Several other medications may also be considered.
Important note regarding Aspirin’s possible use during Covid-19
Always ask your doctor or pharmacist before taking or changing medications of any kind.
The above is a question posed by me. It is based on a hypothetical connection which is based on the present prophylactic use of aspirin – as has been used in the past. Every individual should discuss any medication changes with their medical healthcare professional.
Stephen Bray 2020