Colchicine (Page 2 of 6)

2.5 Dose Modification in Renal Impairment

Colchicine dosing must be individualized according to the patient’s renal function [see Use in Specific Populations(8.6)]. Cl cr in mL/minute may be estimated from serum creatinine (mg/dL) determination using the following formula:

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Caution should be taken in dosing patients with moderate and severe renal impairment and in patients undergoing dialysis. For these patients, the dosage should be reduced [ see Clinical Pharmacology (12.3)]. Patients with mild (Cl cr 50 to 80 mL/min) and moderate (Cl cr 30 to 50 mL/min) renal impairment should be monitored closely for adverse effects of colchicine tablets. Dose reduction may be necessary. For patients with severe renal failure (Cl cr less than 30 mL/min), start with 0.3 mg/day; any increase in dose should be done with adequate monitoring of the patient for adverse effects of colchicine [ see Use in Specific Populations(8.6)].For patients undergoing dialysis, the total recommended starting dose should be 0.3 mg (half tablet) per day. Dosing can be increased with close monitoring. Any increase in dose should be done with adequate monitoring of the patient for adverse effects of colchicine [ see Clinical Pharmacology (12.3), Use in Specific Populations(8.6)].

2.6 Dose Modification in Hepatic Impairment

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Patients with mild to moderate hepatic impairment should be monitored closely for adverse effects of colchicine. Dose reduction should be considered in patients with severe hepatic impairment [see Use in Specific Populations( 8.7)].

3 DOSAGE FORMS AND STRENGTHS

Tablets: 0.6mg colchicine — purple, film-coated, capsule-shaped tablets debossed with ‘G 02’ on one side and scored on the other side.

4 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.

5 WARNINGS AND PRECAUTIONS

5.1 Fatal Overdose

Fatal overdoses, both accidental and intentional, have been reported in adults and children who have ingested colchicine [ see Overdosage (10)].Colchicine should be kept out of the reach of children.

5.2 Blood Dyscrasias

Myelosuppression, leukopenia, granulocytopenia, thrombocytopenia, pancytopenia and aplastic anemia have been reported with colchicine used in therapeutic doses.

5.3 Drug Interactions

Colchicine is a P-gp and CYP3A4 substrate. Life-threatening and fatal drug interactions have been reported in patients treated with colchicine given with P-gp and strong CYP3A4 inhibitors. If treatment with a P-gp or strong CYP3A4 inhibitor is required in patients with normal renal and hepatic function, the patient’s dose of colchicine may need to be reduced or interrupted [see Drug Interactions (7)]. Use of colchicine in conjunction with P-gp or strong CYP3A4 inhibitors (this includes all protease inhibitors except fosamprenavir) is contraindicated in patients with renal or hepatic impairment [ see Contraindications (4)].

5.4 Neuromuscular Toxicity

Colchicine-induced neuromuscular toxicity and rhabdomyolysis have been reported with chronic treatment in therapeutic doses. Patients with renal dysfunction and elderly patients, even those with normal renal and hepatic function, are at increased risk. Concomitant use of atorvastatin, simvastatin, pravastatin, fluvastatin, lovastatin, gemfibrozil, fenofibrate, fenofibric acid or benzafibrate (themselves associated with myotoxicity) or cyclosporine with colchicine may potentiate the development of myopathy [ see Drug Interactions (7)]. Once colchicine is stopped, the symptoms generally resolve within one week to several months.

6 ADVERSE REACTIONS

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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.

6.2 Postmarketing Experience

Serious toxic manifestations associated with colchicine include myelosuppression, disseminated intravascular coagulation and injury to cells in the renal, hepatic, circulatory and central nervous systems.
These most often occur with excessive accumulation or overdosage [ see Overdosage (10)].
The following adverse reactions have been identified with colchicine. These have been generally reversible upon temporarily interrupting treatment or lowering the dose of colchicine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.


Neurological: sensory motor neuropathy
Dermatological: alopecia, maculopapular rash, purpura, rash
Digestive: abdominal cramping, abdominal pain, diarrhea, lactose intolerance, nausea, vomiting
Hematological: leukopenia, granulocytopenia, thrombocytopenia, pancytopenia, aplastic anemia
Hepatobiliary: elevated AST, elevated ALT
Musculoskeletal: myopathy, elevated CPK, myotonia, muscle weakness, muscle pain, rhabdomyolysis Reproductive: azoospermia, oligospermia

7 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:

Pharmacokinetic and/or pharmacodynamic

interaction: the addition of one drug to a stable long-term regimen of the other has resulted in myopathy and

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:

P-gp substrate; rhabdomyolysis has been reported

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