Aspirin - Acetylsalicylic Acid
Aspirin - Acetylsalicylic Acid
Developed by German chemist Felix Hoffmann in 1897, acetylsalicylic acid or Aspirin as it is popularly known is a safe and effective treatment for many an ailment ranging from moderate fever to swelling or even blood clotting. This over-the-counter medication is probably one of the widest selling drugs.
Aspirin: Interestingly, Aspirin is a medicine that has found its way into the Guiness Book of Records. In the year 1950, aspirin recorded entry into the Guinness Book of Records as the highest selling drug product. People are familiar with a common adage which says 'take aspirin at bed time to cut heart attack risk in the morning'. This is a finding of a research that is popular amongst people but has not been published in a peer-reviewed medical journal.
World over, millions of people are familiar with Aspirin as a medicine to relieve pain, aches, fever and inflammation. In such instances, Aspirin is an anti-prostaglandin. Aspirin is also antiplatelet blood thinner medicine. It restricts the ability of the platelets to stick together which in turn reduces the risk of formation of blood clots.
Aspirin is used to treat headache, migraine, muscular pain, neuralgia and sore throat. Aspirin or acetylsalicylic acid has anti-coagulant properties as well as analgesic and antipyretic properties. This drug is a NSAID - non steroidal anti inflammatory drug. Prostaglandins - a family of chemicals are produced within the body's cells by the enzyme cyclo oxygenase (COX).
Further there are 2 kinds of COX enzymes - COX 1 and COX 2 which produce prostaglandins which in turn promote pain, inflammation and fever. Non steroidal anti inflammatory drugs - NSAIDS act by blocking the COX enzymes and reduce prostaglandins thereby reducing the pain, fever and inflammation. In this process of reducing the prostaglandins, NSAID promotes bleeding and may contribute to stomach ulcers. Aspirin is an unique NSAID in the sense that it inhibits clotting of blood for prolonged period - up to 4 to 7 days. It is used to reduce temperature and is commonly recommended for pain relief as in the case of dental pain. Aspirin works as a pain killer by working on the sensitivity of the nerves both at the site of the pain as well as the central nervous system. FDA has approved the use of aspirin in the following conditions:
Heart conditions : The FDA has approved the use of aspirin to reduce the risk of fatality in the event of a heart attack. Aspirin taken during a suspected heart attack can also lessen the damaging effects of the heart attack. Persons who have already suffered a heart attack or unstable angina are put on a course of aspirin to reduce the risk of another heart attack. Aspirin is also recommended for use in people who have suffered transient ischemic attack (TIA or mini-stroke). FDA has endorsed the use of low dose aspirin (75 and 325 mg) for lowering the risk of heart attack and strokes. Aspirin helps in improving blood flow through narrowed blood vessels.
Side Effects of Aspirin: Side effects from aspirin are relatively rare. If you are prone to heartburn or indigestion, ensure that you take aspirin after food. Some people experience rashes or vomiting or stomach pain after taking aspirin. Rarely are side effects such as ringing in the ears, dizziness or mental confusion noticed. In such a case, consult a doctor immediately. Recent research indicates that regular intake of Aspirin on a daily basis can increase the risk of age related Macular Degeneration. Rarely some men have reported blood in the semen - a condition called as Haematospermia.
Contraindications: Aspirin must not be taken on an empty stomach. Persons suffering from peptic ulcer must consult the doctor for the recommended dosage. Aspirin must not be taken along with alcohol. Aspirin and other salicylates should not be taken during the last 3 months of pregnancy or while breast-feeding. It is essential to keep the doctor informed if you are allergic to aspirin If you are taking medications for high blood pressure, diabetes or any anticoagulants, you must inform your physician before he prescribes aspirin.
Aspirin Resistance Blood Test
Close to 26 million Americans or 20% of adults in USA take low-dose Aspirin daily to prevent heart attacks and strokes. Doctors prescribe Aspirin in low doses to patients to lower the risk of heart attack or stroke, primary or secondary in nature. Aspirin benefits the heart in many ways.
Checks inflammation: Inflammation in the heart is a result of plaque build-up. Over time the plaque build-up narrows the arteries and restricts blood flow. There are chances of blood clot formation which can obstruct blood flow or break off the plaque. This can deeply affect the organ connected to the artery. There is also a possibility of the plaque to break off and cause an obstruction. Clogged arteries increase the chances of heart attack, stroke and sometimes even death. Low dose aspirin becomes essential.
Acetylsalicylic Acid fights inflammation by blocking the action of an enzyme called cyclooxygenase. By blocking this enzyme, the body finds it hard to produce prostaglandins, the chemicals that facilitate the inflammatory response.
Stalls blood clots: Aspirin interferes with and stalls the formation of blood clots. It blocks the action of chemicals that produce blood clots. With specific reference to the heart, blood clot formation can block the artery, the blood vessels that carry oxygen and nutrients to the heart muscle tissue. This increases the risk of heart attack and stroke. If Aspirin is taken, it prevents artery-blocking blood clot formation and the risk is considerably reduced.
Every patient who is prescribed Aspirin need not necessarily respond well and get the preventive benefits. In spite of a daily aspirin, patients with continued high levels of thromboxane are considered to be at increased risk of heart attack or stroke compared to patients without elevated levels. To determine and evaluate that the non-response is due to Aspirin resistance, a test is required. One way to determine is through Aspirin resistance blood test.
People who are likely to be categorized as Aspirin resistance include:
- If diagnosed with a disease such as peripheral vascular disease and other inflammatory processes that produce chemicals (thromboxane) that can reduce aspirin's beneficial effect.
- Those taking medications (such as ibuprofen, Naproxen) that interfere with the intended anti-clotting effect of aspirin.
- Those undergoing high levels of stress
- If genetically poor responders to NSAID therapy
- If the dosage is far too low
- Diabetic persons
- Overweight people
- Older adults.
A blood test using a specific device is used to diagnose Aspirin resistance. The test measures the thromboxane levels (higher levels indicate that aspirin is less effective). The purpose of the test is to determine if a patient is likely to benefit from aspirin. If the blood sample shows that aspirin doesn't inhibit blood clotting as it should, the patient is deemed aspirin resistant. Test results are available in less than 10 minutes.
Doctors prescribe medicines for varied reasons, to cure an ailment, to prevent or stop an infection, to ease symptoms, to reduce risks etc. But if there is one particular group of medicines where there is a need for rigorous monitoring regime when taken, it is blood thinners. Not without a reason. Though approved by the FDA, if not handled properly, prolonged use of blood thinners can be unsafe.
Need for Blood thinners
Blood thinners reduce the ability of the blood to clot. Blood thinners belong to a class of drugs called anticoagulants. Immediately after an injury, a scrape or a cut, the blood coagulates and seals the wound, forming a scab to protect from infection. The blood clots formed will be naturally dissolved in the body after the injury is healed. Here blood clotting is a saver and is essential for the body.
The mechanism is regarded as dangerous when blood clots form in the blood stream without an obvious injury and if the blood clot fails to dissolve naturally after the injury heals. The situation poses great risks as it can block circulation; the blood clot can travel to the arteries or veins in the brain, heart, kidneys, lungs and limbs. This in turn can lead to life-threatening conditions such as heart attack, stroke, damage body's organs and in extreme cases result in loss of life.
An updated (February 2014) American Academy of Neurology (AAN) guideline recommends people with an irregular heartbeat to take blood thinners to reduce the risk of stroke. As per doctor's prescription, every year around 2 million people take blood thinner medications every day. It is strongly recommended that blood thinner be taken only under medical supervision.
New vs. old blood thinners
Warfarin was introduced sixty years ago. It is regarded as the oldest anticoagulant blood thinner medication. For decades, Warfarin was the only blood thinner available to lower risks of stroke. There are new additions. A recent study has showed that new blood thinners might be more effective than older medications.
- Dabigatran (Generic name) approved by FDA in October 2010
- Rivaroxaban (Generic name) approved by FDA in October 2011
- Apixaban (Generic name) approved by FDA in December 2012.
Detailed studies comparing Warfarin with the new addition state the following:
- New drugs are similar or even better than warfarin in preventing stroke.
- As the optimal dose of Warfarin varies from patient to patient, blood levels of patients on Warfarin need to be checked periodically.
- New blood thinner medications are regarded as more convenient because the patients taking them do not need to have blood levels checked.
- A study on effectiveness reflected that new blood thinners were approximately 20% more effective in reducing the risk of stroke and 10 % more effective in reducing the risk of death when compared to warfarin.
- New blood thinners, in addition to being more convenient, are potentially more effective than and similar in safety to warfarin.
- New blood thinners are more expensive than Warfarin.
- Long-term safety and side effects of new blood thinners is not yet available.
- With Warfarin, it is easier to reverse the blood thinning effect if a patient is bleeding or needs urgent surgery.
Types of blood thinners
It is chemical formulations that contribute to preventing clotting in various ways. Broadly blood thinner medications are classified into anticoagulant and anti platelet blood thinners.
Anticoagulant blood thinners
Anticoagulant blood thinner medications help decrease the tendency of blood clot formation. There are two ways to decrease the formation of blood clots in the body. Anticoagulants can interfere with platelets or block the body's production of clotting substances. Anticoagulant blood thinners are prescribed for people who have had a condition caused by a blood clot or are at risk of developing one.
Anticoagulant blood thinners are usually given by mouth. In some cases anticoagulants are given intravenously or by injecting them just under the skin (subcutaneously).
Warfarin: Warfarin is the generic drug. In the US, Warfarin is sold under the brand names Coumadin and Jantoven. Doctors prescribe Warfarin for two reasons, to prevent the formation of harmful blood clots or treat an existing blood clot. Some conditions for which Warfarin is prescribed include:
- Atrial fibrillation
- After a heart attack
- Clotting disorder
- Heart valve disease or heart valve replacement
- Treatment or prevention of Deep Venous Thrombosis (blood clots in the veins) and/or pulmonary embolism (blood clots in the lungs).
Patients prescribed Warfarin ought to know how Warfarin works. Knowing helps limit the intake of vitamin K rich foods like dark green vegetables such as broccoli, spinach, turnip greens, green peas etc. At any time, the blood needs certain proteins to clot. These proteins are made in the liver. To enable the liver in the process, Vitamin K is required.
When Warfarin is administered, it reduces the liver's ability to use Vitamin K. Warfarin and Vitamin K work against each other. Thus, the formation of blood clot becomes harder. The interaction between Warfarin and Vitamin K explains the need to partake a diet that is constant in Vitamin K while on Warfarin. The dosage of Warfarin may vary from person to person. A blood test may be recommended to determine the dosage. This blood test, Prothrombin Time or International Normalized Ratio is required to monitor the body's response to Warfarin. Based on test results, Warfarin dose will be determined.
Side effects of Warfarin
Warfarin or Heparin, a common side effect of any anticoagulant medication is the risk of excessive bleeding. As these medicines prolong or lengthen or makes blood clot formation harder, it increases the time for formation of blood clots. If the time taken is too long, there is a possibility of excessive bleeding. There are other symptoms to look out for which are more common with Warfarin. Patients on Warfarin should immediately seek medical attention for any these common Warfarin side effects.
- passing blood in your urine or feces (stools)
- passing black feces
- severe bruising
- prolonged nosebleeds for more than 10 minutes
- bleeding gums
- blood while throwing up (vomiting)
- coughing up blood
- unusual headaches
- sudden severe back pain
- difficulty breathing or chest pain
Women who take Warfarin should contact health care provider if they experience heavy or increased bleeding during menstruation or any other bleeding from the vagina.
Irrespective of the gender, some patients may experience rashes, diarrhea, nausea, hair loss while on Warfarin. These are not common side effects but are termed as additional side effects of Warfarin.
Doctors do advice patients to seek help if the patient is involved in a major accident, experiences a significant blow to the head and finds it difficult to stop bleeding, if any. As Warfarin can interact with many other medicines, so do inform the doctor about all the medications being taken.
Warfarin during pregnancy: Warfarin should be avoided during pregnancy and women with certain health conditions like high blood pressure, ulcer in the digestive tract should not take Warfarin as it can lead to severe health complications.
Long terms risks of using Warfarin: Extensive research on prolonged use of Warfarin suggests that the risk increases with age. The patient is at risk of serious or even fatal bleeding including internal bleeding. In particular the risks are:
- Bleeding strokes, or brain strokes (hemorrhage strokes)
- Calcium build-up in the arteries and narrowing of the aortic valve that goes from the heart and carries oxygen to the body (aortic valve stenosis)
Heparin: Heparin is the generic name. In US, Heparin is available under the brand names Lipohepin, liquaemin and Panheparin. Heparin decreases the clotting ability of the blood and also prevents existing clots from getting larger. Thereby, the normal body systems dissolve the clots that are already formed. Heparin is usually administered as an injection. Heparin can be injected subcutaneously or as an intravenous infusion. The advantage of IV is that it can be turned off quickly for safety reasons. Heparin is prescribed for conditions such as:
- Deep venous thrombosis
- Arterial embolism
- Pulmonary embolism
- Prevention of blood clot during heart surgery, dialysis or blood transfusions
- Peripheral artery obstruction by a foreign substance or a blood clot
- Treatment to prevent peripheral artery thrombo-embolism.
It helps to know how heparin works. Heparin ensures that an anti-clotting protein which is present in the body works better, thus decreasing the clotting ability of the blood.
Available in different strengths, the doctor must prescribe the strength depending on the purpose for which it is prescribed. During the course of treatment, the doctor may increase or decrease the dosage.
Side effects of heparin
A unique possible side effect of Heparin is that several weeks after stopping the injection, bleeding episodes may occur. If the patient notices bruising or unusual bleeding such as a nosebleed, blood in the urine or stools, black or tarry stools or any other bleeding that doesn't cease, contact your healthcare provider.
Besides the common side effects of anticoagulant medications, Heparin's other side effects are visible at that point where the solution is injected.
Herparin during pregnancy: FDA category for Heparin is C meaning there isn't established information that proves whether Heparin affects the fetus. It is best for pregnant women as well as breast-feeding mothers to use Heparin only if the medicine is prescribed by the doctor.
Long term risks of using Heparin
Prolonged use of Heparin particularly in the elderly may cause osteoporosis, a condition in which the bones become weak and may break easily.
Antiplatelet blood thinners
Antiplatelet blood thinner medications work to prevent the platelets (small cells in the blood) from clumping together to form a blood clot. This happens by inhibiting the production of thromboxane, a chemical that signals other platelets to come together. By inhibiting the production of thromboxane, platelets cease to come together to form the blood clot.
Thromboxane's role is helpful for a normal healthy individual who has suffered a wound. It acts as a self-sealing material. But, in the case of a stroke survivor, thromboxane's ability to bind and form a blood clot is potentially life-threatening. Hence, the need to use an antiplatelet blood thinner which are usually available in the form of tablets only.
Doctors prescribe antiplatelet Aspirin to patients who have had a stroke or TIA (transient ischemic attack) so as to reduce the risk of having another stroke. This is possible with Aspirin as it interferes with the blood's clotting action. The dosage varies from patient to patient and is largely guided by the patient's health condition.
Though Aspirin is available OTC (over the counter), doctors recommend low doses of Aspirin for patients with the following medical history.
- Patients who have had prior heart attacks
- Patients who have had prior strokes
- Patients with exertional and unstable angina
- Patients with TIAs (transient ischemic attack called mini-stroke)
- Patients at risk of atherosclerosis.
Aspirin is prescribed to patients who are considered to be at risk of having heart attack or stroke. Anyone with high cholesterol, high blood pressure, diabetic and smoke aggressively are regarded to be at risk of having heart attack or stroke.
Side effect of Aspirin
Most common side effect of taking low doses of Aspirin (100 mg dose) is heartburn and stomach upset. Seldom has there been a very serious side effect related to taking Aspirin as a blood thinner medication. However it is best to be aware of possible serious side effects such as bruising/bleeding, difficulty hearing, ringing in the ears, and change in urine amount, persistent or severe nausea /vomiting, unexplained tiredness, dizziness, dark urine, yellowing of eyes or skin.
Aspirin during pregnancy
The FDA has not assigned formally a pregnancy category. Aspirin is not recommended for use during pregnancy and while breast-feeding as it excretes into breast milk in small amounts.
Other antiplatelet blood thinners
Besides Aspirin, other antiplatelet medicines that are prescribed to prevent the platelets from sticking together include the following. Doctors prescribe a specific antiplatelet blood thinner taking into account the specific health condition and relative effectiveness of the blood thinner medicine. New drugs are continually added to the list with FDA approval.
- Aspirin plus clopidogrel (brand name Plavix) is prescribed for patients who are diagnosed with coronary syndrome such as unstable angina or have had a heart attack, if stent is implanted or if the patient has had a stroke or mini stroke.
- Aspirin plus extended dipyridamole (brand name Aggrenox) is prescribed for patients who have had a stroke or mini stroke (TIA).
- Clopidogrel (brand name Plavix) is recommended by doctors if Aspirin is not suitable for a patient who has been diagnosed with acute coronary syndrome or had a stent implanted.
Long term risks of using Aspirin
Daily use of aspirin can have serious side effects including internal bleeding. Prolonged use of aspirin at higher doses (> 500 mg) can cause stomach ulcers, and can also prolonged bleeding.