ABSTRACT: Objective: Review the magnitude and clinical relevance of drug-drug interactions between a new formulation of colchicine, used to treat gout, and antibiotics.Setting and Practice Description: Relevant to community and institutional pharmacists servicing patients with gout.Practice Innovation: Pharmacists have clear roles for the identification of drug-drug interactions, providing recommendations for alternative therapy or dose adjustments/modifications, and monitoring for interactionrelated adverse events.Main Outcome Measures: Colchicine is metabolized via cytochrome P450 3A4 (CYP3A4); therefore, coadministration with agents that inhibit this isoenzyme can produce elevated colchicine plasma concentrations, resulting in severe and sometimes fatal adverse events. Knowledge of the potential for drug-drug interactions involving antibiotics (e.g., macrolide antibiotics, azole antifungals) allows pharmacists to help patients avoid serious adverse events.Results: Pharmacokinetic studies have demonstrated that the maximum plasma concentration (Cmax) and drug exposure (as assessed by area under the plasma concentration time curve [AUC]) of colchicine are increased by 277% and 282%, respectively, after coadministration with clarithromycin. Similarly, coadministration with ketoconazole increases colchicine Cmax and AUC by 102% and 212%, respectively. Other antibiotics that are strong CYP3A4 inhibitors include itraconazole and telithromycin, whereas erythromycin and fluconazole are moderate inhibitors of the isoenzyme CYP3A4. Coadministration of CYP3A4 inhibitors (particularly clarithromycin) and colchicine has resulted in acute colchicine toxicity manifested by severe gastrointestional toxicity, bone marrow suppression, multiorgan failure, and death.Conclusion: Pharmacist awareness of potentially clinically significant interactions between colchicine and antibiotics that inhibit CYP3A4 can help to ensure the efficacy of colchicine is realized while mitigating serious toxicities and minimizing the risk of adverse events.
The Consultant pharmacist: the journal of the American Society of Consultant Pharmacists 03/2013; 28(3):176-83.
ABSTRACT: The labeling for colchicine (indicated for acute gout flares or prophylaxis) includes strict advisories regarding drug-drug and drug-food interactions, including warnings against consuming grapefruit or grapefruit juice during treatment. Two of the furocoumarins in grapefruit juice and Seville orange juice can inhibit intestinal cytochrome P450 (CYP) isozyme 3A4 and P-glycoprotein (involved in colchicine metabolism and transport). Severe toxicities in patients consuming these juices while taking other drugs metabolized through these pathways have been reported.
Two Phase I studies assessed the effects of multiple daily consumptions of Seville orange juice or grapefruit juice on the pharmacokinetic properties of colchicine in healthy volunteers.
Healthy volunteers were enrolled in 2 open-label, Phase I studies. Undiluted juice (240 mL) was administered twice daily for 4 days. Pharmacokinetic data were obtained following a single 0.6-mg dose of colchicine before the administration of juice and again following a single 0.6-mg dose of colchicine on the final day of juice administration. In each study, blood samples for pharmacokinetics were collected before dosing with colchicine and at 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, and 24 hours postdose. All subjects were monitored for adverse events (AEs) throughout the confinement portion of the study and were queried at the outpatient visits. AEs were coded according to corresponding MedDRA-coded system organ classes.
Forty-four subjects received either grapefruit juice (72.7% male; 90.9% white) or Seville orange juice (62.5% female; 100% white). Although it is considered to be a moderate concentration-dependent CYP3A4 inhibitor, grapefruit juice did not significantly affect the pharmacokinetic parameters of colchicine. When colchicine was administered with Seville orange juice, a moderate inhibitor, C(max) and AUC were decreased by ∼24% and ∼20%, respectively. Seville orange juice also caused, on average, a 1-hour delay in T(max). Colchicine in combination with grapefruit or Seville orange juice was well tolerated. There were no significant treatment-related AEs reported, and the most likely AEs were general gastrointestinal events.
In contrast to label warnings based on the literature, grapefruit juice did not affect the pharmacokinetics of colchicine. Seville orange juice paradoxically reduced absorption of colchicine and increased T(max), but the clinical significance of this is unknown. Contrary to the expected effects of inhibiting the enzymes that metabolize colchicine, neither juice increased exposure to colchicine. However, the absence of a positive control in these studies dictates that caution should be used when applying these results clinically. ClinicalTrials.gov identifiers: NCT00960193 and NCT00984009.
Clinical Therapeutics 08/2012; 34(10):2161-73. · 2.32 Impact Factor
ABSTRACT: Colchicine and cyclosporine are often administered together, particularly in patients who have undergone solid-organ transplantation. However, the potential for drug-drug interactions between these agents resulting in colchicine toxicity is high.
This study sought to determine the effect of cyclosporine (100-mg capsule) on the pharmacokinetics of the US Food and Drug Administration-approved formulation of colchicine (0.6-mg tablet) after single oral-dose administration in 24 healthy subjects under fasted conditions in a phase 1, single-sequence, 2-period drug-drug interaction trial.
Coadministration of cyclosporine increased colchicine maximum observed plasma concentration, area under the plasma concentration-time curve to the last measurable time point, and area under the plasma concentration-time curve to time infinity on average by 224%, 216%, and 215% (ie, almost doubled), respectively, and decreased colchicine oral clearance on average by 72% (from 48.24 to 13.42 L/h), indicating substantially higher colchicine exposures when combined with cyclosporine, compared with colchicine alone.
The dose of colchicine should be reduced by ≥ 50% when colchicine and cyclosporine are administered concurrently for treatment and prophylaxis of gout flares or treatment of patients with familial Mediterranean fever. Health care professionals should be vigilant for potential adverse events during colchicine/cyclosporine coadministration, notably in patients who have undergone solid-organ transplantation.Trial registration: www.ClinicalTrials.gov identifier NCT00983931 (http://clinicaltrials.gov/ct2/show/NCT00983931).
Postgraduate Medicine 07/2012; 124(4):189-96. · 1.78 Impact Factor
ABSTRACT: The objective of this study was to compare the relative bioavailability of the US Food and Drug Administration-approved formulation of colchicine after a single 0.6 mg dose in young (18-30 years of age) and elderly (≥60 years of age) healthy subjects to determine whether dosing adjustments are required in elderly patients.
A single-dose, single-drug, parallel-group study was performed in 20 young subjects with normal renal function (defined as creatinine clearance [CrCl] ≥80 mL/min) and 18 elderly subjects with normal or mild renal impairment (CrCl ≥50 mL/min) in otherwise good health. Blood samples were collected for up to 72 hours postdose and analyzed for colchicine using a validated liquid chromatography/tandem mass spectrometry method. Noncompartmental pharmacokinetic parameters were compared using analysis of variance methods.
There were no statistically significant (P < 0.05) differences in mean colchicine pharmacokinetic parameters between young and elderly subjects, including peak plasma concentration (C(max)) (2.53 vs. 2.56 ng/mL), time to C(max) (1.25 vs. 1.25 hours), area under the plasma concentration-time curve to infinity (22.29 vs. 25.01 ng/h/mL), elimination half-life (25.4 vs. 30.1 hours), oral clearance (0.40 vs. 0.35 L/h/kg), and apparent volume of distribution (14.3 vs. 14.8 L/kg), respectively.
The lack of any significant differences in colchicine pharmacokinetic parameters between young and elderly healthy subjects, with some of the latter including mild renal impairment, suggests that dose modification of colchicine may not be necessary in healthy elderly patients. However, when evaluating the use of colchicine dosing in an elderly patient, the confounding effect on overall exposure and safety from comorbid conditions, the use of concomitant medications, and the administration of multiple doses should be considered.
Advances in Therapy 06/2012; 29(6):551-61. · 2.11 Impact Factor