Indomethacin

Common Uses

Indomethacin is primarily prescribed to manage symptoms associated with chronic and acute inflammatory conditions. It is commonly used for the following:

• Arthritis: It helps treat moderate to severe symptoms of rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis.
• Gout: It is used to manage the intense pain and inflammation associated with acute gouty arthritis.
• Shoulder Pain: It is used to treat acute painful shoulder conditions, specifically bursitis and tendinitis.

This medication works by reducing the production of substances in the body that cause inflammation and pain. It is often utilized when other treatments have not provided sufficient relief for joint stiffness and swelling.

Mechanism of Action

Indomethacin belongs to a group of medicines known as nonsteroidal anti-inflammatory drugs (NSAIDs). It works by stopping the body's production of certain natural chemicals called prostaglandins.

Prostaglandins are produced by the body in response to injury or certain diseases. These chemicals contribute to several physical responses, including:

• Inflammation: Causing swelling, redness, and heat in the affected area.
• Pain: Increasing the sensitivity of nerve endings.
• Fever: Signaling the brain to raise the body's temperature.

Indomethacin blocks the enzymes, specifically cyclooxygenase-1 and cyclooxygenase-2, that are responsible for making these prostaglandins. By lowering the levels of these chemicals, the medication helps to reduce swelling, stiffness, and pain associated with conditions such as arthritis, gout, and bursitis.

While indomethacin helps manage the symptoms of inflammation and pain, it does not cure the underlying condition causing those symptoms.

Common Side Effects

Indomethacin may cause several common side effects as the body adjusts to the medication. These typically include:

• Headache, dizziness, or drowsiness
• Nausea, vomiting, or stomach upset
• Diarrhea, constipation, or gas
• Ringing in the ears

Serious Side Effects

Seek medical attention immediately if you experience any of the following serious symptoms:

• Signs of an allergic reaction, such as hives, skin rash, or swelling of the face, lips, or throat
• Chest pain, shortness of breath, slurred speech, or sudden weakness on one side of the body
• Black, tarry, or bloody stools, or vomiting blood that looks like coffee grounds
• Unexplained weight gain or swelling in the legs, ankles, or feet
• Yellowing of the skin or eyes
• Painful or difficult urination
• Vision changes or sensitivity to light

If you are using rectal suppositories, you may also experience rectal irritation, redness, or a frequent urge to have a bowel movement.

Cardiovascular and Gastrointestinal Risks

Indomethacin may increase the risk of serious cardiovascular thrombotic events, such as heart attack and stroke, which can be fatal. This risk may occur early in treatment and may increase with longer use. It is contraindicated for the treatment of pain before or after coronary artery bypass graft (CABG) surgery.

This medication can also cause serious gastrointestinal (GI) adverse events, including inflammation, bleeding, ulceration, and perforation of the stomach or intestines. These events can occur at any time during use and without warning symptoms. Older adults and those with a history of peptic ulcer disease or GI bleeding are at higher risk.

Allergic Reactions and Respiratory Issues

Individuals with a history of asthma, hives, or other allergic-type reactions after taking aspirin or other NSAIDs should not use indomethacin. Severe, sometimes fatal, anaphylactic reactions have been reported in such patients.

Organ Function and Monitoring

• Kidney Health: Long-term use of NSAIDs can result in kidney injury. Patients with pre-existing kidney disease, heart failure, or liver dysfunction, and those taking certain medications like diuretics, are at increased risk.
• Liver Health: Elevations of liver enzymes may occur. In rare cases, severe hepatic reactions, including jaundice and fatal fulminant hepatitis, have been reported.
• Blood Pressure: Indomethacin can lead to the onset of new high blood pressure or the worsening of existing hypertension, which may contribute to cardiovascular events.

Pregnancy and Fertility

Use of indomethacin during pregnancy, particularly starting at 30 weeks gestation, should be avoided as it may cause premature closure of the fetal ductus arteriosus. Use around 20 weeks gestation or later may also lead to fetal kidney problems and low amniotic fluid. Additionally, NSAIDs may delay or prevent ovulation, potentially affecting fertility in females.

Other Precautions

Indomethacin may cause serious skin adverse events, such as exfoliative dermatitis, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Treatment should be discontinued at the first appearance of a skin rash or any other sign of hypersensitivity. The drug may also mask the usual signs and symptoms of infection.

Pregnancy

Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID). Taking NSAIDs around 20 weeks of pregnancy or later may cause rare but serious kidney problems in an unborn baby. This can lead to low levels of amniotic fluid, which is the liquid that surrounds the baby in the womb.

Healthcare providers typically advise against using indomethacin starting at 30 weeks of pregnancy. At this stage, the medication can cause the premature closure of a vital blood vessel in the baby's heart, known as the ductus arteriosus. This can lead to high blood pressure in the baby's lungs and other serious complications.

If you are pregnant or planning to become pregnant, it is important to discuss the risks and benefits of this medication with your healthcare provider. They will determine if the treatment is necessary or if a safer alternative is available.

Breastfeeding

Indomethacin passes into breast milk in small amounts. Because of the potential for side effects in a nursing infant, you should consult your doctor before breastfeeding while taking this medication. A healthcare professional can help you weigh the benefits of breastfeeding against any potential risks to the infant.

Oral Formulations

Indomethacin is commonly taken by mouth and is available in the following oral forms:

• Capsules: Standard immediate-release capsules.
• Extended-release capsules: These are designed to release the medication slowly over a longer period.
• Oral suspension: A liquid version of the medication.

Rectal Formulations

For patients who cannot take medication by mouth, indomethacin is available as a rectal suppository.

Injectable Formulations

Indomethacin is also available as a sterile powder that is reconstituted into a solution for intravenous injection. This form is typically administered by a healthcare professional in a hospital setting.

FDA Approval and Indications

Indomethacin is approved by the U.S. Food and Drug Administration (FDA) for the treatment of several inflammatory conditions. These include:

• Moderate to severe rheumatoid arthritis
• Moderate to severe osteoarthritis
• Moderate to severe ankylosing spondylitis
• Acute painful shoulder (bursitis and tendinitis)
• Acute gouty arthritis

Boxed Warning

The FDA requires a boxed warning for indomethacin, as with other nonsteroidal anti-inflammatory drugs (NSAIDs), due to the following serious risks:

• Cardiovascular Risk: NSAIDs may cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction (heart attack) and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use.
• Gastrointestinal Risk: NSAIDs cause an increased risk of serious gastrointestinal (GI) adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time during use and without warning symptoms. Elderly patients are at greater risk for serious GI events.

Safety Communications

The FDA has issued safety communications regarding the use of NSAIDs like indomethacin during pregnancy. It is recommended that pregnant women avoid using these medications around 20 weeks or later in pregnancy, as they may cause rare but serious kidney problems in an unborn baby, which can lead to low levels of amniotic fluid.

Dependence and Withdrawal

Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID) and is not considered habit-forming. It does not lead to physical dependence or addiction, so there is no specific withdrawal process required when you stop taking it.

Return of Symptoms

While there is no withdrawal syndrome, stopping indomethacin may cause the symptoms of the condition being treated to return or worsen. This may include:

• Increased joint pain or stiffness
• Return of swelling or inflammation
• Flare-ups of gout or arthritis

Medication Overuse Headaches

If indomethacin is used frequently to treat headaches, stopping the medication or using it too often can sometimes lead to medication overuse headaches, also known as rebound headaches. This occurs when the body becomes accustomed to the medication for pain relief, and the headache returns as the drug wears off.

It is important to follow your healthcare provider's instructions regarding how and when to stop taking this medication to ensure your condition remains managed.