What is the Difference Between Allopurinol and Colchicine

The key difference between Allopurinol and Colchicine is that allopurinol is a medication commonly used to treat gout by inhibiting the xanthine oxidase enzyme, while colchicine is a nonsteroid anti-inflammatory agent primarily used to treat acute gout attacks within 24 hours of the onset by downregulating inflammatory responses.

A gout is a painful form of inflammatory arthritis characterized by a reduction in renal uric acid excretion and an increase in the articular deposition of monosodium urate crystals. Allopurinol is a xanthine oxidase inhibitor used to treat gout by reducing the uric acid crystals in the joints. In contrast, colchicine is a nonsteroid anti-inflammatory agent (NSAID) used to treat gout by preventing immune cell migration to the affected joints, thereby lowering the inflammation and pain related to gout. Both medications should be prescribed and taken under the guidance of a professional healthcare provider.

CONTENTS

1. Overview and Key Difference
2. What is Allopurinol 
3. What is Colchicine
4. Similarities – Allopurinol and Colchicine
5. Allopurinol vs Colchicine in Tabular Form
6. Summary – Allopurinol vs Colchicine

What is Allopurinol?

Allopurinol, chemically known as 4-hydroxypyrazolo (3,4-d) pyrimidine (4-HPP), is a first-line medication frequently used to treat acute gout. It inhibits the purine breakdown pathway of the xanthine oxidase, preventing the conversion of hypoxanthine to xanthine and xanthine to uric acid. The inhibition of the purine breakdown pathway by allopurinol lowers uric acid levels in the serum and tissues, making it effective against gout. This drug has been approved for doses up to 800 mg/d in gout treatment by the US Food and Drug Administration (FDA). However, the suggested starting dose for treating gout is 100 mg/d, increasing to 100 mg daily until the uric acid level becomes 6 mg/d. The common side effects of allopurinol include skin rash, liver abnormalities, and gastrointestinal (GI) intolerance, such as nausea and diarrhoea, and the effect is dose-dependent.

The most common form of allopurinol is oral administration. After the administration, the drug is well absorbed with the peak plasma concentration within 1-2 hours and widely distributed in the body. Allopurinol is metabolized in the liver to an active metabolite called oxypurinol and is eliminated through the kidneys via urine. The half-life of allopurinol is relatively shorter, from 1-2 hours. Nevertheless, the half-life of oxypurinol is much longer, ranging from 18-30 hours.

What is Colchicine?

Colchicine is a tricyclic lipid-soluble alkaloid derived from Colchicum autumnale and belongs to the drug class of nonsteroid anti-inflammatory agents (NSAID) used to treat acute gout conditions. The mechanism of action of low-dose colchicine (0.5 mg/d) is associated with the inhibition of NOD-like receptor proteins (NLRP3) inflammasome to block the release of Interleukin-1 beta (IL-1β), inhibition of cyclooxygenase 2, and suppression of the expression of genes involved in cell regulation. According to the American College of Rheumatology guidelines for the management of gout, it is recommended to use colchicine within 24 hours of the onset of the disease. Colchicine can also be used as a preventive measure to reduce the frequency and intensity of gout attacks.

Colchicine is available in tablet and capsule form, is typically taken orally, and is absorbed in the jejunum and ileum. After the intake, the serum concentration of colchicine reaches a maximum within hours and rapidly binds with the serum albumin. The hepatic P450 cytochrome (CYP3A4) metabolizes the absorbed colchicine in the liver or is directly cleared by the kidneys through glomerular filtration.

What are the Similarities Between Allopurinol and Colchicine?

• Allopurinol and colchicine are commonly used to treat gout.
• They can also be used as preventive measures to decrease the occurrence of gout attacks.
• Both medications are often prescribed for long-term use in gout management.
• Both allopurinol and colchicine are prescription drugs, meaning that they require authorization from healthcare professionals.

What is the Difference Between Allopurinol and Colchicine?

Both allopurinol and colchicine are primarily used for managing gout. However, there is a significant difference between Allopurinol and Colchicine. Allopurinol is a long-term medication for gout prevention and works by inhibiting the xanthine oxidase inhibitor that reduces uric acid production. In contrast, colchicine is a nonsteroidal anti-inflammatory agent used to treat acute gout attacks by inhibiting the functions of immune cells.

 Allopurinol is typically administered once daily, whereas colchicine is taken orally at the onset of an attack. Therefore, allopurinol reduces uric acid levels within days, while colchicine relieves pain within 18 to 24 hours. Moreover, the half-life of allopurinol is 1-2 hours, whereas colchicine has a half-life of 27-31 hours. Allopurinol is associated with side effects such as skin rash and liver function abnormalities, while colchicine commonly causes gastrointestinal symptoms. Allopurinol has additional indications for conditions like kidney stones and certain cancer treatments, while colchicine is also used for familial Mediterranean fever and pericarditis management

Below is a summary of the difference between Allopurinol and Colchicine in tabular form for side-by-side comparison.

Summary – Allopurinol vs Colchicine

In summary, allopurinol and colchicine are commonly used to treat gout. Allopurinol is a xanthine oxidase inhibitor that lowers uric acid levels in the body. In contrast, colchicine is a nonsteroidal anti-inflammatory agent that reduces inflammation and relieves pain associated with gout attacks. Allopurinol is taken long-term for gout prevention, while colchicine is used primarily to treat acute gout attacks. The dosages, administration, half-life, onset of action, and side effects of the two medications differ. Understanding the difference between Allopurinol and Colchicine is important for properly using and managing these medications in treating gout and related conditions.

Reference:

1. Sahu, Sunil Kumar, et al. “DNA Extraction Protocol for Plants with High Levels of Secondary Metabolites and Polysaccharides without Using Liquid Nitrogen and Phenol.” ISRN Molecular Biology, vol. 2012, 2012, pp. 1–6.
2. Slobodnick, Anastasia, et al. “Update on Colchicine, 2017.” Rheumatology, vol. 57, no. suppl_1, 2017, pp. i4–i11.

Image Courtesy:

1. “Allopurinol V.1” By Jü – Own work (Public Domain) via Commons Wikimedia
2. “Colchicin” (Public Domain) via Commons Wikimedia