Allopurinol - Uses, Dosage, Side Effects, Precautions, and Warnings

What Is Allopurinol Used For?

Allopurinol is a class of medication that inhibits the activity of xanthine oxidase and treats gout and specific kidney stones. The drug is often used to manage leukemia, lymphoma, and malignancies which may cause elevated serum and uric acid levels. Allopurinol can manage patients with recurrent calcium kidney stones and elevated uric acid levels. Allopurinol is a Food and Drug Administration (FDA)-approved medication that prevents tumor lysis syndrome.

How Does Allopurinol Work?

Allopurinol helps to reduce uric acid production by inhibiting biochemical reactions. Allopurinol is metabolized in the liver into its active metabolite or oxypurinol. The oxypurinol inhibits the xanthine oxidase enzyme in the purine catabolism pathway and converts hypoxanthine to xanthine to uric acid. Allopurinol increases the reuse of hypoxanthine and xanthine for nucleotide and nucleic acid synthesis. This causes increased nucleotide concentration resulting in decreased urine and serum uric acid concentration. The half-life of Allopurinol is one to two hours, and oxypurinol is about 15 hours. Therefore, the kidney primarily eliminates Allopurinol and its metabolites.

How to Take Allopurinol?

Allopurinol is available as an oral tablet to be taken once or twice a day, preferably after a meal. The medicine should be taken at the same time each day. It is advised to take eight to ten glasses of fluid daily to reduce the risk of kidney stones. It may be required to have regular blood tests to monitor uric acid levels. There may be more gout attacks initially when Allopurinol is started, and it may take up to two to six weeks for symptoms of gout to reduce. When taken regularly, Allopurinol can lower the number of gout attacks and help to prevent damage to the joints.

What Is the Dosage of Allopurinol?

The recommended dose of Allopurinol is 100 mg to 300 mg a day. Allopurinol is usually started on a low dose. The duration and the dosage depend on

• Age.

• The condition that is being treated.

• The severity of the condition.

• Other medical conditions.

• Reaction to the first dose.

What Precautions to Be Taken When Taking Allopurinol?

• Allergies - Allopurinol can cause severe allergic reactions. The drug should be avoided if you have ever been allergic to Allopurinol or other similar medicines.

• Pregnancy and Breastfeeding - Allopurinol is a category C pregnancy drug and can cause adverse effects on the fetus. The drug passes into human breastmilk and may cause side effects in the child.

• Geriatrics - Kidney function deteriorates with age causing older adults to be more susceptible to side effects while taking Allopurinol.

• Children - Allopurinol should be given with caution in children as there can be an increased risk of side effects such as a rash, itchy skin, hives, fever with chills, or blood in urine or stool.

• Liver Disease - Allopurinol may cause changes in the liver function test results and liver disease, which may be fatal.

• Kidney Problems - Allopurinol should be administered cautiously in patients with kidney problems or a history of kidney disease. There can be an increase in the levels of Allopurinol in the body because of delayed clearing of the drug from the body.

• Alertness - Allopurinol can cause drowsiness and should not be taken when driving, handling machinery, or other activity that requires alertness.

• Alcohol - Drinking alcohol can increase the level of uric acid in the blood and can trigger an attack of gout.

What Are the Side Effects of Allopurinol?

Allopurinol can cause serious drug reactions that may affect many parts of your body.

Some of the side effects may include

• Rash.

• Drowsiness.

• Fever and chills.

• Nausea.

• Diarrhea.

• Joint pain.

• Painful urination.

• Easy bruising.

• Numbness, tingling, burning pain.

• Loss of appetite.

• Weight loss.

• Irritation of the eyes.

• Swelling of lips or mouth.

• Blood in urine or stool.

• Sore throat.

• Muscle aches.

• Little or no urination.

• Yellowing of the skin or eyes.

• Severe skin rash or redness can develop into a life-threatening skin condition called Stevens-Johnson syndrome, which may cause flu-like symptoms followed by red or purple rash or blister.

What Will Happen If You Stop Taking Allopurinol?

Allopurinol should not be stopped suddenly as there is an increased risk of worsening gout or serious side effects. The doctor will reduce the dose gradually.

What Are the Interactions of Allopurinol?

Drug Interactions:

• Azathioprine.

• Mercaptopurine.

• Chlorpropamide.

• Cyclosporine.

• Antibiotics such as Ampicillin or Amoxicillin.

• Anticoagulants such as Warfarin, Coumadin, or Jantoven.

• Diuretics such as Furosemide.

• Enalapril.

• Ramipril.

Food Interaction:

• Coffee - Drinking coffee in moderation can reduce the risk of gout as it can lower the rate at which uric acid is formed.

• Vitamin C - High vitamin C intake can increase plasma ascorbate in Allopurinol patients. Vitamin supplements or food rich in vitamin C can significantly reduce serum uric acid levels.

Interaction with Diseases:

• Bone Marrow Suppression - Therapy with Allopurinol should be administered with caution to patients with or predisposed to bone marrow suppression as it can cause suppression in these people as early as six weeks to as long as six years.

• Dehydration - It is important to be adequately hydrated during Allopurinol therapy to prevent the formation of xanthine calculi and renal precipitation of urates.

• Liver Disease - Therapy with Allopurinol should be administered cautiously in patients with liver disease as there can be asymptomatic elevated serum transaminase and alkaline phosphatase levels. Periodic monitoring of liver function is recommended in these patients during the early stages of therapy.

• Renal Dysfunction - Patients with decreased renal function may require a lower dose of Allopurinol. Individuals with preexisting renal disease should be monitored regularly with periodic renal function tests.

• Thyroid Problems - Increased thyroid-stimulating hormone levels can be observed in patients receiving long-term Allopurinol treatment.

Conclusion:

Allopurinol can be used for the long-term treatment of gout. It is important to monitor certain health issues like kidney and liver function tests and uric acid tests while taking Allopurinol to stay safe while taking this medicine. Eating a diet low in animal protein and oxalate-rich foods such as spinach, beets, celery, and green beans is recommended to check uric acid levels.