1.1 Gout Flares

Colchicine tablets, USP are indicated for prophylaxis and the treatment of acute gout flares.

• Prophylaxis of Gout Flares:

Colchicine tablets, USP are indicated for prophylaxis of gout flares.

• Treatment of Gout Flares:

Colchicine tablets, USP are indicated for treatment of acute gout flares when taken at the first sign of a flare.

1.2 Familial Mediterranean Fever (FMF)

Colchicine tablets, USP are indicated in adults and children four years or older for treatment of familial Mediterranean fever (FMF).

2.1 Gout Flares

Prophylaxis of Gout Flares

The recommended dosage of colchicine tablets, USP for prophylaxis of gout flares for adults and adolescents older than 16 years of age is 0.6 mg once or twice daily. The maximum recommended dose for prophylaxis of gout flares is 1.2 mg/day.

An increase in gout flares may occur after initiation of uric acid-lowering therapy, including pegloticase, febuxostat and allopurinol, due to changing serum uric acid levels resulting in mobilization of urate from tissue deposits. Colchicine tablets, USP are recommended upon initiation of gout flare prophylaxis with uric acid-lowering therapy. Prophylactic therapy may be beneficial for at least the first six months of uric acid-lowering therapy.

Treatment of Gout Flares

The recommended dose of colchicine tablets, USP for treatment of a gout flare is 1.2 mg (two tablets) at the first sign of the flare followed by 0.6 mg (one tablet) one hour later. Higher doses have not been found to be more effective. The maximum recommended dose for treatment of gout flares is 1.8 mg over a 1-hour period. Colchicine tablets, USP may be administered for treatment of a gout flare during prophylaxis at doses not to exceed 1.2 mg (two tablets) at the first sign of the flare followed by 0.6 mg (one tablet) one hour later. Wait 12 hours and then resume the prophylactic dose.

2.2 FMF

The recommended dosage of colchicine tablets, USP for FMF in adults is 1.2 mg to 2.4 mg daily.

Colchicine tablets, USP should be increased as needed to control disease and as tolerated in increments of 0.3 mg/day to a maximum recommended daily dose. If intolerable side effects develop, the dose should be decreased in increments of 0.3 mg/day. The total daily colchicine tablets, USP dose may be administered in one to two divided doses.

2.3 Recommended Pediatric Dosage

Prophylaxis and Treatment of Gout Flares

Colchicine tablets, USP are not recommended for pediatric use in prophylaxis or treatment of gout flares.

FMF

The recommended dosage of colchicine tablets, USP for FMF in pediatric patients 4 years of age and older is based on age. The following daily doses may be given as a single or divided dose twice daily:

• Children 4 to 6 years: 0.3 mg to 1.8 mg daily
• Children 6 to 12 years: 0.9 mg to 1.8 mg daily
• Adolescents older than 12 years: 1.2 mg to 2.4 mg daily

2.4 Dose Modification for Co-administration of Interacting Drugs

Concomitant Therapy

Co-administration of colchicine tablets, USP with drugs known to inhibit CYP3A4 and/or P-glycoprotein (P-gp) increases the risk of colchicine-induced toxic effects (Table 1). If patients are taking or have recently completed treatment with drugs listed in Table 1 within the prior 14 days, the dose adjustments are as shown in the table below [see Drug Interactions (7)].

Table 1. Colchicine Tablets, USP Dose Adjustment for Co-administration with Interacting Drugs if No Alternative Available*

Table 2. Colchicine Tablets, USP Dose Adjustment for Co-administration with Protease Inhibitors

Treatment of gout flares with colchicine tablets, USP is not recommended in patients receiving prophylactic dose of colchicine tablets, USP and CYP3A4 inhibitors.

2.5 Dose Modification in Renal Impairment

Colchicine, USP 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:

            [140-age (years) × weight (kg)]

Cl cr = ---------------------------------------- × 0.85 for female patients

             72 × serum creatinine (mg/dL)

Gout Flares

Prophylaxis of Gout Flares

For prophylaxis of gout flares in patients with mild (estimated creatinine clearance [Cl cr] 50 to 80 mL/min) to moderate (Cl cr 30 to 50 mL/min) renal function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. However, in patients with severe impairment, the starting dose should be 0.3 mg/day and any increase in dose should be done with close monitoring. For the prophylaxis of gout flares in patients undergoing dialysis, the starting doses should be 0.3 mg given twice a week with close monitoring [see Clinical Pharmacology (12.3), Use in Specific Populations (8.6)] .

Treatment of Gout Flares

For treatment of gout flares in patients with mild (Cl cr 50 to 80 mL/min) to moderate (Cl cr 30 to 50 mL/min) renal function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. However, in patients with severe impairment, while the dose does not need to be adjusted for the treatment of gout flares, a treatment course should be repeated no more than once every two weeks. For patients with gout flares requiring repeated courses, consideration should be given to alternate therapy. For patients undergoing dialysis, the total recommended dose for the treatment of gout flares should be reduced to a single dose of 0.6 mg (one tablet). For these patients, the treatment course should not be repeated more than once every two weeks [see Clinical Pharmacology (12.3), Use in Specific Populations (8.6)] .

Treatment of gout flares with colchicine tablets, USP is not recommended in patients with renal impairment who are receiving colchicine tablets, USP for prophylaxis.

FMF
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, USP. 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

Gout Flares

Prophylaxis of Gout Flares

For prophylaxis of gout flares in patients with mild to moderate hepatic function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. Dose reduction should be considered for the prophylaxis of gout flares in patients with severe hepatic impairment [see Use in Specific Populations (8.7)] .

Treatment of Gout Flares

For treatment of gout flares in patients with mild to moderate hepatic function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. However, for the treatment of gout flares in patients with severe impairment, while the dose does not need to be adjusted, a treatment course should be repeated no more than once every two weeks. For these patients, requiring repeated courses for the treatment of gout flares, consideration should be given to alternate therapy [see Use in Specific Populations (8.7)] .

Treatment of gout flares with colchicine tablets, USP is not recommended in patients with hepatic impairment who are receiving colchicine tablets, USP for prophylaxis.

FMF
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)] .

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.

6.1 Clinical Trials Experience in Gout

Because clinical studies are conducted under widely varying and controlled conditions, adverse reaction rates observed in clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not predict the rates observed in a broader patient population in clinical practice.

In a randomized, double-blind, placebo-controlled trial in patients with a gout flare, gastrointestinal adverse reactions occurred in 26% of patients using the recommended dose (1.8 mg over one hour) of colchicine compared to 77% of patients taking a non-recommended high dose (4.8 mg over six hours) of colchicine and 20% of patients taking placebo. Diarrhea was the most commonly reported drug-related gastrointestinal adverse event. As shown in Table 3, diarrhea is associated with colchicine treatment. Diarrhea was more likely to occur in patients taking the high-dose regimen than the low-dose regimen. Severe diarrhea occurred in 19% and vomiting occurred in 17% of patients taking the non-recommended high-dose colchicine regimen but did not occur in the recommended low-dose colchicine regimen.

Table 3. Number (%) of Patients with at Least One Drug-Related Treatment-Emergent Adverse Event with an Incidence of ≥2% of Patients in Any Treatment Group

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

8.1 Pregnancy

Risk Summary

Available data from published literature on colchicine use in pregnancy over several decades have not identified any drug associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Data). Colchicine crosses the human placenta. Although animal reproductive and developmental studies were not conducted with colchicine, published animal reproduction and development studies indicate that colchicine causes embryofetal toxicity, teratogenicity and altered postnatal development at exposures within or above the clinical therapeutic range.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Data

Human Data

Available data from published observational studies, case series, and case reports over several decades do not suggest an increased risk for major birth defects or miscarriage in pregnant women with rheumatic diseases (such as rheumatoid arthritis, Behcet’s disease, or familial Mediterranean fever (FMF) treated with colchicine at therapeutic doses during pregnancy. Limitations of these data include the lack of randomization and inability to control for confounders such as underlying maternal disease and maternal use of concomitant medications.

8.2 Lactation

Risk Summary

Colchicine is present in human milk (see Data). Adverse events in breastfed infants have not been reported in the published literature after administration of colchicine to lactating women. There are no data on the effects of colchicine on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for colchicine and any potential adverse effects on the breastfed child from colchicine or from the underlying maternal condition.

Data

Limited published data from case reports and a small lactation study demonstrate that colchicine is present in breastmilk. A systematic review of literature reported no adverse effects in 149 breastfed children. In a prospective observational cohort study, no gastrointestinal or other symptoms were reported in 38 colchicine-exposed breastfed infants.

8.3 Females and Males of Reproductive Potential

Infertility

Case reports and epidemiology studies in human male subjects on colchicine therapy indicated that infertility from colchicine is rare and may be reversible. A case report indicated that azoospermia was reversed when therapy was stopped. Case reports and epidemiology studies in female subjects on colchicine therapy have not established a clear relationship between colchicine use and female infertility. However, since the progression of FMF without treatment may result in infertility, the use of colchicine needs to be weighed against the potential risks [see Nonclinical Toxicology (13.1)] .

8.4 Pediatric Use

The safety and efficacy of colchicine in children of all ages with FMF has been evaluated in uncontrolled studies. There does not appear to be an adverse effect on growth in children with FMF treated long-term with colchicine. Safety and effectiveness of colchicine in pediatric patients with gout has not been established.

8.5 Geriatric Use

Clinical studies with colchicine for prophylaxis and treatment of gout flares and for treatment of FMF did not include sufficient numbers of patients aged 65 years and older to determine whether they respond differently from younger patients. In general, dose selection for an elderly patient with gout should be cautious, reflecting the greater frequency of decreased renal function, concomitant disease or other drug therapy [see Dosage and Administration (2.4), Clinical Pharmacology (12.3)] .

8.6 Renal Impairment

Colchicine is significantly excreted in urine in healthy subjects. Clearance of colchicine is decreased in patients with impaired renal function. Total body clearance of colchicine was reduced by 75% in patients with end-stage renal disease undergoing dialysis.

Prophylaxis of Gout Flares

For prophylaxis of gout flares in patients with mild (estimated creatinine clearance Cl cr 50 to 80 mL/min) to moderate (Cl cr 30 to 50 mL/min) renal function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. However, in patients with severe impairment, the starting dose should be 0.3 mg per day and any increase in dose should be done with close monitoring. For the prophylaxis of gout flares in patients undergoing dialysis, the starting doses should be 0.3 mg given twice a week with close monitoring [see Dosage and Administration (2.5)] .

Treatment of Gout Flares

For treatment of gout flares in patients with mild (Cl cr 50 to 80 mL/min) to moderate (Cl cr 30 to 50 mL/min) renal function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. However, in patients with severe impairment, while the dose does not need to be adjusted for the treatment of gout flares, a treatment course should be repeated no more than once every two weeks. For patients with gout flares requiring repeated courses, consideration should be given to alternate therapy. For patients undergoing dialysis, the total recommended dose for the treatment of gout flares should be reduced to a single dose of 0.6 mg (one tablet). For these patients, the treatment course should not be repeated more than once every two weeks [see Dosage and Administration (2.5)] .

FMF

Although pharmacokinetics of colchicine in patients with mild (Cl cr 50 to  80 mL/min) and moderate (Cl cr 30 to 50 mL/min) renal impairment is not known, these patients should be monitored closely for adverse effects of colchicine. Dose reduction may be necessary. In patients with severe renal failure (Cl cr less than 30 mL/min) and end-stage renal disease requiring dialysis, colchicine may be started at the dose of 0.3 mg/day. Any increase in dose should be done with adequate monitoring of the patient for adverse effects of colchicine [see Clinical Pharmacology (12.3), Dosage and Administration (2.5)] .

8.7 Hepatic Impairment

The clearance of colchicine may be significantly reduced and plasma half-life prolonged in patients with chronic hepatic impairment compared to healthy subjects [see Clinical Pharmacology (12.3)] .

Prophylaxis of Gout Flares

For prophylaxis of gout flares in patients with mild to moderate hepatic function impairment, adjustment of the recommended dose is not required, but patients should be monitored closely for adverse effects of colchicine. Dose reduction should be considered for the prophylaxis of gout flares in patients with severe hepatic impairment  [see Dosage and Administration (2.6)] .

Treatment of Gout Flares

For treatment of gout flares in patients with mild to moderate hepatic function impairment, adjustment of the recommended colchicine dose is not required, but patients should be monitored closely for adverse effects of colchicine. However, for the treatment of gout flares in patients with severe impairment, while the dose does not need to be adjusted, the treatment course should be repeated no more than once every two weeks. For these patients, requiring repeated courses for the treatment of gout flares, consideration should be given to alternate therapy [see Dosage and Administration (2.6)] .

FMF
In patients with severe hepatic disease, dose reduction should be considered with careful monitoring [see Clinical Pharmacology (12.3), Dosage and Administration (2.6)] .

12.1 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.

12.3 Pharmacokinetics

Absorption

In healthy adults, colchicine is absorbed when given orally, reaching a mean C max of 2.5 ng/mL (range 1.1 to 4.4 ng/mL) in one to two hours (range 0.5 to 3 hours) after a single dose administered under fasting conditions.

Following oral administration of colchicine given as 1.8 mg colchicine over one hour to healthy, young adults under fasting conditions, colchicine appears to be readily absorbed, reaching mean maximum plasma concentrations of 6.2 ng/mL at a median 1.81 hours (range: 1 to 2.5 hours). Following administration of the nonrecommended high-dose regimen (4.8 mg over six hours), mean maximal plasma concentrations were 6.8 ng/mL, at a median 4.47 hours (range: 3.1 to 7.5 hours).

After ten days on a regimen of 0.6 mg twice daily, peak concentrations are 3.1 to 3.6 ng/mL (range 1.6 to 6 ng/mL), occurring 1.3 to 1.4 hours post dose (range 0.5 to 3 hours). Mean pharmacokinetic parameter values in healthy adults are shown in Table 5.

Table 5. Mean (%CV) Pharmacokinetic Parameters in Healthy Adults Given Colchicine

 In some subjects, secondary colchicine peaks are seen, occurring between three and 36 hours post dose and ranging from 39% to 155% of the height of the initial peak. These observations are attributed to intestinal secretion and reabsorption and/or biliary recirculation.

Absolute bioavailability is reported to be approximately 45%.

Administration of colchicine with food has no effect on the rate of colchicine absorption but does decrease the extent of colchicine by approximately 15%. This is without clinical significance.

Distribution

The mean apparent volume of distribution in healthy young volunteers is approximately 5 to 8 L/kg.

Colchicine binding to serum protein is low, 39 ± 5%, primarily to albumin regardless of concentration.

Colchicine crosses the placenta (plasma levels in the fetus are reported to be approximately 15% of the maternal concentration). Colchicine also distributes into breast milk at concentrations similar to those found in the maternal serum [see Use in Specific Populations (8.1, 8.2)] .

Metabolism

Colchicine is demethylated to two primary metabolites, 2-O-demethylcolchicine and 3-O-demethylcolchicine (2- and 3-DMC, respectively) and one minor metabolite, 10-O-demethylcolchicine (also known as colchicine). In vitro studies using human liver microsomes have shown that CYP3A4 is involved in the metabolism of colchicine to 2- and 3-DMC. Plasma levels of these metabolites are minimal (less than 5% of parent drug).

Elimination/Excretion

In healthy volunteers (n=12), 40% to 65% of 1 mg orally administered colchicine was recovered unchanged in urine. Enterohepatic recirculation and biliary excretion are also postulated to play a role in colchicine elimination. Following multiple oral doses (0.6 mg twice daily), the mean elimination half-lives in young healthy volunteers (mean age 25 to 28 years of age) is 26.6 to 31.2 hours. Colchicine is a substrate of P-gp.

Extracorporeal Elimination

Colchicine is not removed by hemodialysis.

Special Populations

There is no difference between men and women in the pharmacokinetic disposition of colchicine.

Pediatric Patients

Pharmacokinetics of colchicine was not evaluated in pediatric patients.

Elderly

A published report described the pharmacokinetics of 1 mg oral colchicine tablet in four elderly women compared to six young healthy males. The mean age of the four elderly women was 83 years (range 75 to 93), mean weight was 47 kg (38 to 61 kg) and mean creatinine clearance was 46 mL/min (range 25 to 75 mL/min). Mean peak plasma levels and AUC of colchicine were two times higher in elderly subjects compared to young healthy males.

A pharmacokinetic study using a single oral dose of one 0.6 mg colchicine tablet was conducted in young healthy subjects (n=20) between the ages of 18 and 30 years and elderly subjects (n=18) between the ages of 60 and 70 years. Elderly subjects in this study had a median age of 62 years and a mean (±SD) age of 62.83 ± 2.83 years. A statistically significant difference in creatinine clearance (mean ± SD) was found between the two age groups (132.56 ± 23.16 mL/min for young vs. 87.02 ± 17.92 mL/min for elderly subjects, respectively). The following pharmacokinetic parameter values (mean ± SD) were observed for colchicine in the young and elderly subjects, respectively: AUC 0-inf (ng/hr/mL) 22.39 ± 6.95 and 25.01 ± 6.92; C max (ng/mL) 2.61 ± 0.71 and 2.56 ± 0.97; T max (hr) 1.38 ± 0.42 and 1.25 ± 0.43; apparent elimination half-life (hr) 24.92 ± 5.34 and 30.06 ± 10.78; and clearance (mL/min) 0.0321 ± 0.0091 and 0.0292 ± 0.0071.

Clinical studies with colchicine prophylaxis and treatment of gout flares and for treatment of FMF did not include sufficient numbers of patients aged 65 years and older to determine whether they respond differently than younger patients. In general, dose selection for an elderly patient with gout should be cautious, reflecting the greater frequency of decreased renal function, concomitant disease or other drug therapy [see Dosage and Administration (2.4), Use in Specific Populations (8.5)] .

Renal Impairment

Pharmacokinetics of colchicine in patients with mild and moderate renal impairment is not known. A published report described the disposition of colchicine (1 mg) in young adult men and women with FMF who had normal renal function or end-stage renal disease requiring dialysis. Patients with end-stage renal disease had 75% lower colchicine clearance (0.17 vs. 0.73 L/hr/kg) and prolonged plasma elimination half-life (18.8 vs. 4.4 hours) as compared to subjects with FMF and normal renal function [see Dosage and Administration (2.5), Use in Specific Populations (8.6)] .

Hepatic Impairment

Published reports on the pharmacokinetics of IV colchicine in patients with severe chronic liver disease, as well as those with alcoholic or primary biliary cirrhosis and normal renal function suggest wide interpatient variability. In some subjects with mild to moderate cirrhosis, the clearance of colchicine is significantly reduced and plasma half-life prolonged compared to healthy subjects. In subjects with primary biliary cirrhosis, no consistent trends were noted [see Dosage and Administration (2.6), Use in Specific Populations (8.7)] . No pharmacokinetic data are available for patients with severe hepatic impairment (Child-Pugh C).

Drug Interactions

In Vitro Drug Interactions

In vitro studies in human liver microsomes have shown that colchicine is not an inhibitor or inducer of CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 or CYP3A4 activity.

In Vivo Drug Interactions

The effects of co-administration of other drugs with colchicine on C max, AUC and C min are summarized in Table 6 (effect of other drugs on colchicine) and Table 7 (effect of colchicine on other drugs). For information regarding clinical recommendations, see Table 1 in Dose Modification for Co-administration of Interacting Drugs [see Dosage and Administration (2.4)] .

Table 6. Drug Interactions: Pharmacokinetic Parameters for Colchicine Tablets in the Presence of the Co-Administered Drug

Estrogen-containing oral contraceptives: In healthy female volunteers given ethinyl estradiol and norethindrone (Ortho-Novum 1/35) co-administered with colchicine (0.6 mg twice daily × 14 days), hormone concentrations are not affected.

In healthy volunteers given theophylline co-administered with colchicine (0.6 mg twice daily × 14 days), theophylline concentrations were not affected.

Table 7. Drug Interactions: Pharmacokinetic Parameters for Co-Administration of Drug in the Presence of Colchicine Tablets

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

Two year studies were conducted in mice and rats to assess the carcinogenic potential of colchicine. No evidence of colchicine-related tumorigenicity was observed in mice or rats at colchicine oral doses up to 3 and 2 mg/kg/day, respectively (approximately six and eight times, respectively, the maximum recommended human dose of 2.4 mg on a mg/m 2 basis).

Mutagenesis

Colchicine was negative for mutagenicity in the bacterial reverse mutation assay. In a chromosomal aberration assay in cultured human white blood cells, colchicine treatment resulted in the formation of micronuclei. Since published studies demonstrated that colchicine induces aneuploidy from the process of mitotic nondisjunction without structural DNA changes, colchicine is not considered clastogenic, although micronuclei are formed.

Impairment of Fertility

No studies of colchicine effects on fertility were conducted with colchicine. However, published nonclinical studies demonstrated that colchicine-induced disruption of microtubule formation affects meiosis and mitosis. Reproductive studies also reported abnormal sperm morphology and reduced sperm counts in males, and interference with sperm penetration, second meiotic division and normal cleavage in females when exposed to colchicine. Colchicine administered to pregnant animals resulted in fetal death and teratogenicity. These effects were dose-dependent, with the timing of exposure critical for the effects on embryofetal development. The nonclinical doses evaluated were generally higher than an equivalent human therapeutic dose, but safety margins for reproductive and developmental toxicity could not be determined.

16.1 How Supplied

Colchicine tablets, USP, 0.6 mg, are purple, capsule-shaped, film-coated tablets, scored on one side and debossed with ”A10” on the other side.

They are available as:

NDC 50268-187-15 (10 tablets per card, 5 cards per carton).

For Institutional Use Only. Dispensed in Unit Dose Package.

16.2 Storage

Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Protect from light.

DISPENSE IN TIGHT, LIGHT-RESISTANT CONTAINER.