Epirubicin Hydrochloride

EPIRUBICIN HYDROCHLORIDE- epirubicin hydrochloride injection, solution
APP Pharmaceuticals, LLC

WARNING

  1. Severe local tissue necrosis will occur if there is extravasation during administration (see PRECAUTIONSsection). Epirubicin must not be given by the intramuscular or subcutaneous route.
  2. Myocardial toxicity, manifested in its most severe form by potentially fatal congestive heart failure (CHF), may occur either during therapy with epirubicin or months to years after termination of therapy. The probability of developing clinically evident CHF is estimated as approximately 0.9% at a cumulative dose of 550 mg/m2 , 1.6% at 700 mg/m2 , and 3.3% at 900 mg/m2. In the adjuvant treatment of breast cancer, the maximum cumulative dose used in clinical trials was 720 mg/m2. The risk of developing CHF increases rapidly with increasing total cumulative doses of epirubicin in excess of 900 mg/m2 ; this cumulative dose should only be exceeded with extreme caution. Active or dormant cardiovascular disease, prior or concomitant radiotherapy to the mediastinal/pericardial area, previous therapy with other anthracyclines or anthracenediones, or concomitant use of other cardiotoxic drugs may increase the risk of cardiac toxicity. Cardiac toxicity with epirubicin hydrochloride may occur at lower cumulative doses whether or not cardiac risk factors are present.
  3. Secondary acute myelogenous leukemia (AML) has been reported in patients with breast cancer treated with anthracyclines, including epirubicin. The occurrence of refractory secondary leukemia is more common when such drugs are given in combination with DNA-damaging antineoplastic agents, when patients have been heavily pretreated with cytotoxic drugs, or when doses of anthracyclines have been escalated. The cumulative risk of developing treatment-related AML or myelodysplastic syndrome (MDS), in 7110 patients with breast cancer who received adjuvant treatment with epirubicin-containing regimens, was estimated as 0.27% at 3 years, 0.46% at 5 years, and 0.55% at 8 years.
  4. Dosage should be reduced in patients with impaired hepatic function (see DOSAGE AND ADMINISTRATIONsection).
  5. Severe myelosuppression may occur.
  6. Epirubicin should be administered only under the supervision of a physician who is experienced in the use of cancer chemotherapeutic agents.

DESCRIPTION

Epirubicin hydrochloride injection is an anthracycline cytotoxic agent, intended for intravenous administration. Epirubicin hydrochloride injection is supplied as a sterile, clear, red solution and is available in vials containing 50 mg and 200 mg of epirubicin hydrochloride as a preservative-free, ready-to-use solution. Each milliliter of solution contains 2 mg of epirubicin hydrochloride. Inactive ingredients include sodium chloride, USP, and water for injection, USP. The pH of the solution has been adjusted to 3.0 with hydrochloric acid, NF.

Epirubicin hydrochloride is the 4-epimer of doxorubicin and is a semi-synthetic derivative of daunorubicin. The chemical name is (8S-cis )-10-[(3-amino-2,3,6-trideoxy-α-L-arabino -hexopy-ranosyl)oxy]-7,8,9,10-tetrahydro 6,8,11-trihydroxy-8-(hydroxyacetyl)-1-methoxy-5,12-naphthacene- dione hydrochloride. The active ingredient is a red-orange hygroscopic powder, with the molecular formula C27 H29 NO11 HCl and a molecular weight of 579.95. The structural formula is as follows:

Image from Drug Label Content

CLINICAL PHARMACOLOGY

Epirubicin is an anthracycline cytotoxic agent. Although it is known that anthracyclines can interfere with a number of biochemical and biological functions within eukaryotic cells, the precise mechanisms of epirubicin’s cytotoxic and/or antiproliferative properties have not been completely elucidated.

Epirubicin forms a complex with DNA by intercalation of its planar rings between nucleotide base pairs, with consequent inhibition of nucleic acid (DNA and RNA) and protein synthesis. Such intercalation triggers DNA cleavage by topoisomerase II, resulting in cytocidal activity. Epirubicin also inhibits DNA helicase activity, preventing the enzymatic separation of double-stranded DNA and interfering with replication and transcription. Epirubicin is also involved in oxidation/reduction reactions by generating cytotoxic free radicals. The antiproliferative and cytotoxic activity of epirubicin is thought to result from these or other possible mechanisms.

Epirubicin is cytotoxic in vitro to a variety of established murine and human cell lines and primary cultures of human tumors. It is also active in vivo against a variety of murine tumors and human xenografts in athymic mice, including breast tumors.

Pharmacokinetics

Epirubicin pharmacokinetics are linear over the dose range of 60 to 150 mg/m2 and plasma clearance is not affected by the duration of infusion or administration schedule. Pharmacokinetic parameters for epirubicin following 6 to 10 minute, single-dose intravenous infusions of epirubicin at doses of 60 to 150 mg/m2 in patients with solid tumors are shown in Table 1. The plasma concentration declined in a triphasic manner with mean half-lives for the alpha, beta, and gamma phases of about 3 minutes, 2.5 hours, and 33 hours, respectively.

Table 1. Summary of Mean (±SD) Pharmacokinetic Parameters in Patients1 with Solid Tumors Receiving Intravenous Epirubicin 60 to 150 mg/m2
Dose2 (mg/m2)Cmax3 (mcg/mL)AUC4 (mcg.h/mL)t½ 5 (hours)CL6 (L/hour)Vss7 (L/kg)
1 Advanced solid tumor cancers, primarily of the lung 2 N=6 patients per dose level 3 Plasma concentration at the end of 6 to 10 minute infusion4 Area under the plasma concentration curve 5 Half-life of terminal phase 6 Plasma clearance 7 Steady state volume of distribution
605.7 ± 1.61.6 ± 0.235.3 ± 965 ± 821 ± 2
755.3 ± 1.51.7 ± 0.332.1 ± 583 ± 1427 ± 11
1209.0 ± 3.53.4 ± 0.733.7 ± 465 ± 1323 ± 7
1509.3 ± 2.94.2 ± 0.831.1 ± 669 ± 1321 ± 7

Distribution. Following intravenous administration, epirubicin is rapidly and widely distributed into the tissues. Binding of epirubicin to plasma proteins, predominantly albumin, is about 77% and is not affected by drug concentration. Epirubicin also appears to concentrate in red blood cells; whole blood concentrations are approximately twice those of plasma.

Metabolism. Epirubicin is extensively and rapidly metabolized by the liver and is also metabolized by other organs and cells, including red blood cells. Four main metabolic routes have been identified:

  1. reduction of the C-13 keto-group with the formation of the 13(S)-dihydro derivative, epirubicinol;
  2. conjugation of both the unchanged drug and epirubicinol with glucuronic acid;
  3. loss of the amino sugar moiety through a hydrolytic process with the formation of the doxorubicin and doxorubicinol aglycones; and
  4. loss of the amino sugar moiety through a redox process with the formation of the 7-deoxy-doxorubicin aglycone and 7-deoxy-doxorubicinol aglycone. Epirubicinol has in vitro cytotoxic activity one-tenth that of epirubicin. As plasma levels of epirubicinol are lower than those of the unchanged drug, they are unlikely to reach in vivo concentrations sufficient for cytotoxicity. No significant activity or toxicity has been reported for the other metabolites.

Excretion. Epirubicin and its major metabolites are eliminated through biliary excretion and, to a lesser extent, by urinary excretion. Mass-balance data from 1 patient found about 60% of the total radioactive dose in feces (34%) and urine (27%). These data are consistent with those from 3 patients with extrahepatic obstruction and percutaneous drainage, in whom approximately 35% and 20% of the administered dose were recovered as epirubicin or its major metabolites in bile and urine, respectively, in the 4 days after treatment.

Pharmacokinetics in Special Populations

Age. A population analysis of plasma data from 36 cancer patients (13 males and 23 females, 20 to 73 years) showed that age affects plasma clearance of epirubicin in female patients. The predicted plasma clearance for a female patient of 70 years of age was about 35% lower than that for a female patient of 25 years of age. An insufficient number of males >50 years of age were included in the study to draw conclusions about age-related alterations in clearance in males. Although a lower epirubicin starting dose does not appear necessary in elderly female patients, and was not used in clinical trials, particular care should be taken in monitoring toxicity when epirubicin is administered to female patients >70 years of age. (see PRECAUTIONSsection.)

Gender. In patients ≤50 years of age, mean clearance values in adult male and female patients were similar. The clearance of epirubicin is decreased in elderly women (see Pharmacokinetics in Special Populations – Age section).

Pediatric. The pharmacokinetics of epirubicin in pediatric patients have not been evaluated.

Race. The influence of race on the pharmacokinetics of epirubicin has not been evaluated.

Hepatic Impairment. Epirubicin is eliminated by both hepatic metabolism and biliary excretion and clearance is reduced in patients with hepatic dysfunction. In a study of the effect of hepatic dysfunction, patients with solid tumors were classified into 3 groups. Patients in Group 1 (n=22) had serum AST (SGOT) levels above the upper limit of normal (median: 93 IU/L) and normal serum bilirubin levels (median: 0.5 mg/dL) and were given epirubicin doses of 12.5 to 90 mg/m2. Patients in Group 2 had alterations in both serum AST (median: 175 IU/L) and bilirubin levels (median: 2.7 mg/dL) and were treated with an epirubicin dose of 25 mg/m2 (n=8). Their pharmacokinetics were compared to those of patients with normal serum AST and bilirubin values, who received epirubicin doses of 12.5 to 120 mg/m2. The median plasma clearance of epirubicin was decreased compared to patients with normal hepatic function by about 30% in patients in Group 1 and by 50% in patients in Group 2. Patients with more severe hepatic impairment have not been evaluated. (see WARNINGS and DOSAGE AND ADMINISTRATIONsections).

Renal Impairment. No significant alterations in the pharmacokinetics of epirubicin or its major metabolite, epirubicinol, have been observed in patients with serum creatinine <5 mg/dL. A 50% reduction in plasma clearance was reported in four patients with serum creatinine ≥5 mg/dL (see WARNINGS and DOSAGE AND ADMINISTRATIONsections). Patients on dialysis have not been studied.

Drug-Drug Interactions

Taxanes. Coadministration of paclitaxel or docetaxel did not affect the pharmacokinetics of epirubicin when given immediately following the taxane.

Cimetidine. Coadministration of cimetidine (400 mg twice daily for 7 days starting 5 days before chemotherapy) increased the mean AUC of epirubicin (100 mg/m2) by 50% and decreased its plasma clearance by 30% (see PRECAUTIONSsection).Drugs metabolized by cytochrome P-450 enzymes. No systematic in vitro or in vivo evaluation has been performed to examine the potential for inhibition or induction by epirubicin of oxidative cytochrome P-450 isoenzymes.

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