Iressa

Generic Name: Gefitinib
Class: Antineoplastic Agents
VA Class: AN900
Chemical Name: N-(3-chloro-4-fluorophenyl)-7-methoxy-6-[3-(4-morpholin)propoxy]-4-quinazolamine
Molecular Formula: C22H24ClFN4O3
CAS Number: 184475-35-2

Introduction

Antineoplastic agent; synthetic anilinoquinazoline.1 2 3 4

Uses for Iressa

Non-small Cell Lung Cancer (NSCLC)

Monotherapy for continued treatment of locally advanced or metastatic NSCLC after failure of both platinum-based and docetaxel regimens due to disease progression or unacceptable toxicity in patients who are benefiting or have benefited from gefitinib.1

No survival benefit demonstrated.1 Therefore, consider other agents that have been shown to prolong survival (e.g., erlotinib, docetaxel) for management of advanced NSCLC in patients who have received 1 or 2 previous chemotherapy regimens and have refractory disease or unacceptable toxicity.1 12

Slideshow: Flashback: FDA Drug Approvals 2013

Use of gefitinib currently is limited to patients already receiving and benefiting from the drug or who are enrolled in a clinical trial.11 12 13 (See Restricted Distribution Program under Dosage and Administration.)

No benefit from adding gefitinib to initial standard platinum-based chemotherapy in patients with NSCLC or as a component in combination chemotherapy in patients with advanced disease.1 3

Iressa Dosage and Administration

General

  • Consult specialized references for procedures for proper handling and disposal of antineoplastics.

Administration

Oral Administration

Administer orally once daily without regard to meals.1

For patients who have difficulty swallowing solids, prepare dispersion by placing tablet in a half glass of noncarbonated drinking water (do not use other liquids).1 Without crushing the tablet, stir water until tablet is dispersed (approximately 10 minutes).1 Drink liquid (containing dispersed tablet) immediately, then rinse glass with a half glass of water and drink remaining water.1 May also administer the aqueous dispersion through a nasogastric tube.1

Restricted Distribution Program

After September 15, 2005, available only through the Iressa Access Program.12 13 As part of this program, renewal prescriptions are dispensed through a mail order pharmacy for patients meeting specified criteria.13 Contact AstraZeneca at 800-601-8933 or consult the Iressa website () for additional information.13

Dosage

Adults

NSCLC
Oral

250 mg once daily.1 Higher dosages do not increase response and may increase toxicity.1

If used with potent CYP3A4 inducer, consider dosage adjustment.1 (See Interactions.)

Discontinue gefitinib if interstitial lung disease develops.1 (See Pulmonary Toxicity under Cautions.)

May interrupt therapy briefly (up to 14 days) if adverse dermatologic reactions or poorly tolerated diarrhea (sometimes with dehydration) occurs.1 Reinitiate at dosage of 250 mg once daily.1

Interrupt therapy if adverse ocular manifestations (e.g., pain, aberrant eyelash) develop; following resolution, make decision regarding reinitiation at dosage of 250 mg once daily.1

Special Populations

Hepatic Impairment

No dosage adjustments necessary in patients with moderate to severe hepatic impairment and liver metastases.1 9 (See Special Populations under Pharmacokinetics.)

Renal Impairment

No dosage adjustments necessary.1 9 (See Renal Impairment under Cautions.)

Cautions for Iressa

Contraindications

  • Known severe hypersensitivity to gefitinib or any ingredient in the formulation.1

Warnings/Precautions

Warnings

Pulmonary Toxicity

Interstitial lung disease, sometimes fatal, reported; described as interstitial pneumonia, pneumonitis, or alveolitis.1 7 Manifestations often include acute onset of dyspnea, sometimes associated with cough or low-grade fever, usually becoming severe within a short time and requiring hospitalization.1 8

Risk of increased mortality in patients with concurrent idiopathic pulmonary fibrosis whose condition worsens while receiving gefitinib.1

If acute onset or worsening of pulmonary symptoms (dyspnea, cough, fever) occurs, interrupt therapy, promptly evaluate patient, and institute appropriate therapy.1 If diagnosis of interstitial lung disease is confirmed, discontinue gefitinib and provide appropriate treatment.1

Fetal/Neonatal Morbidity and Mortality

May cause fetal harm; neonatal mortality soon after parturition, reduction in number of offspring born alive, and reduced fetal weight demonstrated in animals.1

Avoid pregnancy during therapy; if pregnancy occurs, apprise of potential fetal hazard or risk of pregnancy loss.1

Sensitivity Reactions

Hypersensitivity Reactions

Allergic reactions, including angioedema and urticaria, reported.1

Major Toxicities

GI Effects

Diarrhea, nausea, vomiting, anorexia, and weight loss reported.1

Dermatologic Effects

Rash, acne, and dry skin reported.1 Toxic epidermal necrolysis and erythema multiforme reported rarely.1

Ocular Effects

Ocular pain and corneal erosion or ulcer, sometimes in association with aberrant eyelash growth, reported.1 Corneal membrane sloughing, ocular ischemia, or ocular hemorrhage reported rarely.1

Other Adverse Effects

Hemorrhage (e.g., epistaxis, hematuria) reported.1 Pancreatitis reported rarely.1

General Precautions

Hepatotoxicity

Asymptomatic elevations of hepatic aminotransferase concentrations reported.1

Consider periodic monitoring of liver function (aminotransferase, bilirubin, alkaline phosphatase concentrations); if severe elevations of test results occur, consider discontinuance.1

Specific Populations

Pregnancy

Category D.1 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Lactation

Gefitinib and its metabolites are distributed into milk in rats; not known whether distributed into human milk.1 Women receiving gefitinib should not breast-feed.1

Pediatric Use

Safety and efficacy not established in children <18 years of age; therefore, not indicated for use in pediatric patients.1 9 CNS hemorrhage and death reported in pediatric patients receiving gefitinib alone or with radiation for primary CNS tumors.1

Geriatric Use

No substantial differences in safety and efficacy relative to younger adults.1

Hepatic Impairment

Possible increased exposure.1 (See Special Populations under Pharmacokinetics.)

Renal Impairment

Not studied in patients with severe renal impairment; use with caution.1

Common Adverse Effects

Diarrhea, rash, acne, dry skin, nausea, vomiting, pruritus, anorexia, asthenia.1

Interactions for Iressa

Metabolized principally by CYP3A4.1 Does not inhibit CYP isoenzymes 1A2, 2C9, or 3A4 in vitro, but may inhibit 2C19 and 2D6 at high drug concentrations.1

Drugs Affecting Hepatic Microsomal Enzymes

CYP3A4 inhibitors: Potential pharmacokinetic interaction (decreased gefitinib metabolism, increased plasma gefitinib concentrations).1 2 3 Possible increased risk of adverse effects.1 Use with caution.1

CYP3A4 inducers: Potential pharmacokinetic interaction (increased gefitinib metabolism, decreased plasma gefitinib concentrations).1 If used concomitantly with potent CYP3A4 inducer, consider increasing gefitinib dosage to 500 mg daily in the absence of severe adverse effects.1

Drugs Affecting Gastric Acidity

Possible pharmacokinetic interaction (decreased plasma gefitinib concentrations, possible reduction in gefitinib efficacy) with drugs that cause substantial, sustained gastric pH elevation.1 10

Specific Drugs

Drug

Interaction

Comments

Antifungals, azoles (e.g., itraconazole, ketoconazole)

Decreased metabolism and increased plasma concentrations of gefitinib; possible increased risk of adverse effects1

Use with caution1

Histamine H2-receptor antagonists

Possible decreased plasma gefitinib concentrations and reduction in gefitinib efficacy1

Metoprolol

Increased systemic exposure to metoprolol1

Phenytoin

Increased metabolism and decreased plasma concentrations of gefitinib1

Consider increasing gefitinib dosage to 500 mg daily in the absence of severe adverse effects1

Proton-pump inhibitors

Possible decreased plasma gefitinib concentrations and reduction in gefitinib efficacy1 10

Rifampin

Increased metabolism and decreased plasma concentrations of gefitinib1

Consider increasing gefitinib dosage to 500 mg daily in the absence of severe adverse effects1

Vinorelbine

Possible exacerbation of vinorelbine-induced neutropenia1

Warfarin

Possible INR elevations and/or bleeding1

Monitor regularly for changes in PT or INR1

Iressa Pharmacokinetics

Absorption

Bioavailability

Slowly absorbed following oral administration, with peak plasma concentrations attained within 3–7 hours.1 Mean bioavailability is 60%.1

Food

Food does not substantially alter bioavailability.1

Distribution

Extent

Extensively distributed throughout the body.1

Crosses placenta.1 Gefitinib and its metabolites are distributed into milk in rats; not known whether distributed into human milk.1

Plasma Protein Binding

90% in vitro (albumin and α1-acid glycoprotein).1

Elimination

Metabolism

Extensively metabolized in liver, principally by CYP3A4.1 Five metabolites identified; only O-desmethyl gefitinib has exposure comparable to that of gefitinib, but potency is only 1/14 that of gefitinib.1

Elimination Route

Excreted in feces (86%) and urine (4%).1

Half-life

About 48 hours.1

Special Populations

In patients with hepatic impairment, systemic exposure to gefitinib may be increased, since drug is cleared principally by liver.1 However, in patients with moderate to severe elevations of hepatic enzymes and liver metastases, pharmacokinetic profile was similar to that in patients without hepatic abnormalities;1 9 effect of hepatic impairment unrelated to cancer not evaluated to date.1

Effect of severe renal impairment on pharmacokinetics not determined.1

Stability

Storage

Oral

Tablets

20–25°C.1

Actions

  • Inhibits intracellular phosphorylation of numerous tyrosine kinases associated with transmembrane cell surface receptors, including epidermal growth factor receptor (EGFR) tyrosine kinase;1 2 3 4 activation of EGFR tyrosine kinase may initiate cascade of intracellular signaling events leading to cell proliferation and influencing processes critical to cell survival and tumor progression (e.g., angiogenesis, apoptosis, metastasis).2 4

  • Precise mechanism of antineoplastic activity not fully elucidated; further study needed to determine if correlation exists between EGFR receptor expression and response to gefitinib.1

Advice to Patients

  • Importance of promptly reporting any conditions that can be associated with dehydration (e.g., severe or persistent diarrhea, nausea, anorexia, vomiting), new onset or worsening of pulmonary symptoms (e.g., shortness of breath, cough), ocular irritation, or other new symptoms.1

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed; necessity of advising women to avoid pregnancy and nursing during therapy.1 Advise pregnant women of risk to the fetus.1

  • Importance of informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs and herbal supplements, as well as any concomitant illnesses.1

  • Importance of informing patients of other important precautionary information.1 (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

No longer available through community pharmacies.12 13 Currently available through the Iressa Access Program for selected patients.12 13 (See Restricted Distribution Program under Dosage and Administration.)

Gefitinib

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Tablets, film-coated

250 mg

Iressa (with povidone)

AstraZeneca

AHFS DI Essentials. © Copyright, 2004-2014, Selected Revisions August 26, 2014. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

References

1. AstraZeneca Pharmaceuticals. Iressa (gefitinib) tablets prescribing information. Wilmington, DE; 2005 Jun.

2. Culy CR, Faulds D. Gefitinib. Drugs. 2002; 62:2237-48. [PubMed 12381224]

3. Anon. Gefitinib (Iressa) for advanced non-small cell lung cancer. Med Lett Drugs Ther. 2002; 44:77-8. [PubMed 12205428]

4. Baselga J, Averbuch SD. ZD1839 (Iressa) as an anticancer agent. Drugs. 2000; 60 (suppl 1):33-40. [PubMed 11129170]

5. Kris MG, Natale RB, Herbst RS et al. A phase II trial of ZD1839 (Iressa) in advanced non-small cell lung cancer (NSCLC) patients who had failed platinum- and docetaxel-based regimens (IDEAL 2). 38th Annual Meeting of the American Society of Clinical Oncology (ASCO), Orlando, FL, May 2002. Abstract No. 1166.

6. US Food and Drug Administration. Briefing document NDA 21-399. From FDA website. Accessed 2003 May 22.

7. Inoue A, Saijo Y, Maemondo M et al. Severe acute interstitial pneumonia and gefitinib. Lancet. 2003; 361:137-9. [IDIS 491838] [PubMed 12531582]

8. Kinoshita A, Fukuda M, Nagashima S, et al. Pulmonary damage during gefitinib monotherapy in patients with non-small cell lung cancer. 39th Annual Meeting of the American Society of Clinical Oncology (ASCO), Chicago, IL, May 2003. Abstract No. 2809.

9. AstraZeneca Pharmaceuticals, Wilmington, DE: Personal communication.

10. Zucchero FJ, Hogan MJ, Sommer CD, eds. Evaluations of Drug Interactions. St. Louis, MO: FirstDatabank; 2003:18/902.00.

11. FDA public health advisory: new labeling and distribution program for gefitinib (Iressa). Rockville, MD; 2005 Jun 17. From FDA website.

12. Questions and answers on Iressa (gefitinib). Rockville, MD: Food and Drug Administration; 2005 Jun 17. From FDA website.

13. AstraZeneca Pharmaceuticals. Information for healthcare professionals from website for Iressa.

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