Colchicine (10 brand names, 3 dosage forms, 1 route)
Available dosage forms: CAPSULE, TABLET, SOLUTION.
Routes of administration: ORAL.
Brand Names
- COL-PROBENECID
- COLBENEMID
- COLCHICINE
- COLCRYS
- GLOPERBA
- LODOCO
- MITIGARE
- PROBEN-C
- PROBENECID AND COLCHICINE
- PROBENECID W/ COLCHICINE
Dosage and Administration
The long-term use of colchicine is established for FMF and the prophylaxis of gout flares, but the safety and efficacy of repeat treatment for gout flares has not been evaluated. The dosing regimens for colchicine tablets are different for each indication and must be individualized. The recommended dosage of colchicine depends on the patient’s age, renal function, hepatic function, and use of coadministered drugs [see Dosage and Administration (2.4, 2.5, 2.6)]. Colchicine tablets are administered orally without regard to meals. Colchicine tablets are not an analgesic medication and should not be used to treat pain from other causes.
Contraindications
Patients with renal or hepatic impairment should not be given colchicine in conjunction with P-gp or strong CYP3A4 inhibitors (this includes all protease inhibitors except fosamprenavir). In these patients, life-threatening and fatal colchicine toxicity has been reported with colchicine taken in therapeutic doses.
Adverse Reactions
Prophylaxis of Gout Flares The most commonly reported adverse reaction in clinical trials of colchicine for the prophylaxis of gout was diarrhea. Treatment of Gout Flares The most common adverse reactions reported in the clinical trial with colchicine for treatment of gout flares were diarrhea (23%) and pharyngolaryngeal pain (3%). FMF Gastrointestinal tract adverse effects are the most frequent side effects in patients initiating colchicine, usually presenting within 24 hours, and occurring in up to 20% of patients given therapeutic doses. Typical symptoms include cramping, nausea, diarrhea, abdominal pain and vomiting. These events should be viewed as dose-limiting if severe, as they can herald the onset of more significant toxicity.
Drug Interactions
Colchicine is a substrate of the efflux transporter P-glycoprotein (P-gp). Of the cytochrome P450 enzymes tested, CYP3A4 was mainly involved in the metabolism of colchicine. If colchicine is administered with drugs that inhibit P-gp, most of which also inhibit CYP3A4, increased concentrations of colchicine are likely. Fatal drug interactions have been reported. Physicians should ensure that patients are suitable candidates for treatment with colchicine and remain alert for signs and symptoms of toxicities related to increased colchicine exposure as a result of a drug interaction. Signs and symptoms of colchicine toxicity should be evaluated promptly and, if toxicity is suspected, colchicine should be discontinued immediately. Table 4 provides recommendations as a result of other potentially significant drug interactions. Table 1 provides recommendations for strong and moderate CYP3A4 inhibitors and P-gp inhibitors. Table 4. Other Potentially Significant Drug Interactions Concomitant Drug Class or Food Noted or Anticipated Outcome Clinical Comment HMG-Co A Reductase Inhibitors: atorvastatin, fluvastatin, lovastatin, pravastatin, simvastatin Pharmacokinetic and/or pharmacodynamic interaction: the addition of one drug to a stable longterm regimen of the other has resulted in myopathy and rhabdomyolysis (including a fatality) Weigh the potential benefits and risks and carefully monitor patients for any signs or symptoms of muscle pain, tenderness, or weakness, particularly during initial therapy; monitoring CPK (creatine phosphokinase) will not necessarily prevent the occurrence of severe myopathy. Other Lipid-Lowering Drugs: fibrates, gemfibrozil Digitalis Glycosides: digoxin P-gp substrate; rhabdomyolysis has been reported
Mechanism of Action
The mechanism by which colchicine exerts its beneficial effect in patients with FMF has not been fully elucidated; however, evidence suggests that colchicine may interfere with the intracellular assembly of the inflammasome complex present in neutrophils and monocytes that mediates activation of interleukin-1β. Additionally, colchicine disrupts cytoskeletal functions through inhibition of β-tubulin polymerization into microtubules and consequently prevents the activation, degranulation and migration of neutrophils thought to mediate some gout symptoms.
Overdosage
The exact dose of colchicine that produces significant toxicity is unknown. Fatalities have occurred after ingestion of a dose as low as 7 mg over a four day period, while other patients have survived after ingesting more than 60 mg. A review of 150 patients who overdosed on colchicine found that those who ingested less than 0.5 mg/kg survived and tended to have milder toxicities such as gastrointestinal symptoms, whereas those who took 0.5 to 0.8 mg/kg had more severe reactions such as myelosuppression. There was 100% mortality in those who ingested more than 0.8 mg/kg. The first stage of acute colchicine toxicity typically begins within 24 hours of ingestion and includes gastrointestinal symptoms such as abdominal pain, nausea, vomiting, diarrhea and significant fluid loss, leading to volume depletion. Peripheral leukocytosis may also be seen. Life-threatening complications occur during the second stage, which occurs 24 to 72 hours after drug administration, attributed to multi-organ failure and its consequences. Death is usually a result of respiratory depression and cardiovascular collapse. If the patient survives, recovery of multi-organ injury may be accompanied by rebound leukocytosis and alopecia starting about one week after the initial ingestion. Treatment of colchicine poisoning should begin with gastric lavage and measures to prevent shock. Otherwise, treatment is symptomatic and supportive. No specific antidote is known. Colchicine is not effectively removed by dialysis [see Clinical Pharmacology (12.3)].