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Gentak eent

Generic Name: Gentamicin Sulfate eent
Class: Antibacterials
VA Class: AM300
CAS Number: 1405-41-0

Medically reviewed on Oct 29, 2018

Introduction

Antibacterial; aminoglycoside.101 102

Uses for Gentak

Bacterial Ophthalmic Infections

Topical treatment of superficial bacterial infections of the eye caused by susceptible bacteria, including Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes, S. pneumoniae, Enterobacter aerogenes, Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, Neisseria gonorrhoeae, Serratia marcescens, and Pseudomonas aeruginosa.101 102

Mild, acute bacterial conjunctivitis often resolves spontaneously without anti-infective treatment.135 136 137 141 Although topical ophthalmic anti-infectives may shorten time to resolution and reduce severity and risk of complications,135 136 137 141 avoid indiscriminate use of topical anti-infectives.135 141 Treatment of acute bacterial conjunctivitis generally is empiric;135 136 141 use of a broad-spectrum topical ophthalmic antibacterial usually recommended.135 136 141 In vitro staining and/or cultures of conjunctival material may be indicated in management of recurrent, severe, or chronic purulent conjunctivitis or when acute conjunctivitis does not respond to initial empiric topical treatment.135 136 141

Because bacterial keratitis may be associated with subsequent loss of vision as the result of corneal scarring or topographic irregularities and because untreated or severe bacterial keratitis may result in corneal perforation with potential for endophthalmitis and possible loss of the eye, optimal management involves rapid evaluation and diagnosis, timely initiation of treatment, and appropriate follow-up.138 Treatment of community-acquired bacterial keratitis generally is empiric;138 use of a broad-spectrum topical ophthalmic antibacterial usually recommended.138 Subconjunctival anti-infectives may be necessary if scleral spread or perforation is imminent.138 In vitro staining and/or cultures of corneal material indicated in management of keratitis involving corneal infiltrates that are central, large, and extend to the middle to deep stroma; when keratitis is chronic or unresponsive to a broad-spectrum topical anti-infective; or when atypical features suggest fungal, amebic, or mycobacterial infection.138

Ocular Inflammation

Fixed-combination ophthalmic preparations containing gentamicin and a corticosteroid (i.e., prednisolone): Topical treatment of corticosteroid-responsive ocular conditions when a corticosteroid indicated and superficial bacterial ocular infection or risk of such infection exists.107 108

Although manufacturers state that use of a fixed-combination ophthalmic preparation containing an anti-infective and a corticosteroid may be indicated in ocular inflammatory conditions when risk of superficial ocular infection is high or when potentially dangerous numbers of bacteria are expected to be present in the eye,107 108 experts state avoid use of such preparations in patients with bacterial conjunctivitis because of risk of potentiating the infection.136

Consider that use of fixed-combination ophthalmic preparations containing an anti-infective and a corticosteroid may mask clinical signs of bacterial, fungal, or viral infections; prevent recognition of ineffectiveness of the anti-infective; and/or increase IOP.107 108 (See Use of Fixed combinations Containing Corticosteroids under Cautions.)

Gentak Dosage and Administration

Administration

Ophthalmic Administration

Apply gentamicin ophthalmic ointment or solution topically to the eye.101 102

Apply fixed-combination ophthalmic ointment or suspension containing gentamicin and a corticosteroid (i.e., prednisolone) topically to the eye.107 108

For topical ophthalmic use only;101 102 107 108 do not inject subconjunctivally or directly into anterior chamber of the eye.101 102 108

Avoid contaminating container tip with material from eye, eyelid, or any other source.101 102 107 108

Shake fixed-combination ophthalmic suspension well prior to use.108

Dosage

Available as gentamicin sulfate alone101 102 or in fixed combination with prednisolone acetate.107 108 Dosage of gentamicin expressed in terms of the base;101 102 107 108 dosage of prednisolone acetate expressed in terms of the salt.107 108

Pediatric Patients

Bacterial Ophthalmic Infections
Ophthalmic

Gentamicin 0.3% (ophthalmic ointment) in pediatric patients ≥1 month of age: Apply approximately 1.25-cm (½-inch) ribbon in affected eye(s) 2 or 3 times daily.102

Gentamicin 0.3% (ophthalmic solution) in pediatric patients ≥1 month of age: Instill 1 or 2 drops into affected eye(s) every 4 hours.101 For severe infections, up to 2 drops may be instilled every hour.101

Usual duration of topical anti-infective treatment for bacterial conjunctivitis is 5–10 days;135 136 141 5–7 days usually adequate for mild bacterial conjunctivitis.135

Adults

Bacterial Ophthalmic Infections
Ophthalmic

Gentamicin 0.3% (ophthalmic ointment): Apply approximately 1.25-cm (½-inch) ribbon in affected eye(s) 2 or 3 times daily.102

Gentamicin 0.3% (ophthalmic solution): Instill 1 or 2 drops into affected eye(s) every 4 hours.101 For severe infections, up to 2 drops may be instilled every hour.101

Usual duration of topical anti-infective treatment for bacterial conjunctivitis is 5–10 days;135 136 141 5–7 days usually adequate for mild bacterial conjunctivitis.135

Ocular Inflammation
Ophthalmic

Gentamicin 0.3% and prednisolone acetate 0.6% (ophthalmic ointment): Apply approximately 1.25-cm (½-inch) ribbon into conjunctival sac of affected eye(s) 1–3 times daily.107

Gentamicin 0.3% and prednisolone acetate 1% (ophthalmic suspension): Instill 1 drop into conjunctival sac of affected eye(s) 2–4 times daily.108 During initial 24–48 hours, 1 drop may be instilled every hour if necessary.108

If no improvement after 2 days, reevaluate patient.107 108 Do not discontinue prematurely.107 108

Cautions for Gentak

Contraindications

  • Gentamicin ophthalmic ointment or solution: Hypersensitivity to gentamicin or any ingredient in the formulation.101 102

  • Fixed-combination ophthalmic preparations containing gentamicin and a corticosteroid (i.e., prednisolone): Known or suspected hypersensitivity to gentamicin, prednisolone or other corticosteroids, or any ingredient in the formulation.107 108 Also, patients with viral diseases of the cornea and conjunctiva, including epithelial herpes simplex keratitis (dendritic keratitis), vaccinia, and varicella; with mycobacterial infections of the eye; or fungal diseases of ocular structures.107 108

Warnings/Precautions

Sensitivity Reactions

Hypersensitivity

Allergic reactions reported.101 102

If hypersensitivity occurs, immediately discontinue101 102 and initiate appropriate therapy.101 102

Superinfection

Prolonged use may result in overgrowth of nonsusceptible organisms, including fungi.101 102

Bacterial resistance to gentamicin may occur.101 102

Bacterial and fungal corneal ulcers have developed.101 102

Precautions Related to Ophthalmic Administration

Manufacturer cautions that ophthalmic ointments may delay corneal healing.102

Use of Fixed Combinations Containing Corticosteroids

When ophthalmic preparations containing gentamicin in fixed combination with a corticosteroid (i.e., prednisolone) used, consider cautions, precautions, and contraindications associated with EENT corticosteroids.107 108

Provide initial prescriptions for fixed-combination ophthalmic preparations containing a corticosteroid or renewal prescriptions (beyond 8 g of ophthalmic ointment or beyond 20 mL of ophthalmic solution) only after measuring IOP and examining patient with slit lamp microscopy and, when appropriate, fluorescein staining.107 108

Prolonged use of fixed-combination ophthalmic preparations containing a corticosteroid may result in glaucoma, with optic nerve damage, defects in visual acuity and fields of vision, and posterior subcapsular cataract formation.107 108 If such preparation used for ≥10 days, routinely monitor IOP, even though this may be difficult in children and uncooperative patients.107 108 Use fixed combinations containing a corticosteroid with caution in patients with glaucoma; check IOP frequently in such patients.107 108

Use of fixed-combination ophthalmic preparations containing a corticosteroid after cataract surgery may delay healing and increase incidence of bleb formation.107 108

Corneal and scleral thinning reported with various ocular diseases and with long-term use of topical corticosteroids.107 108 Use of topical corticosteroids in patients with thin corneal and scleral tissue may result in perforation.107 108

Prolonged use of fixed-combination ophthalmic preparations containing a corticosteroid may suppress host responses and increase risk of secondary ocular infections.107 108 Use in patients with acute purulent conditions of the eye may mask infection or enhance existing infection.107 108

May prolong course and exacerbate severity of many viral infections of the eye (including herpes simplex).107 108 Use with great caution in patients with herpes simplex; frequent slit lamp microscopy recommended.107 108

Consider possibility of fungal infections of the cornea after prolonged use of ophthalmic preparations containing a corticosteroid.107 108 Perform fungal cultures when appropriate.107 108

Specific Populations

Pregnancy

No adequate and well-controlled studies using ophthalmic preparations containing gentamicin in pregnant women.102

Use gentamicin ophthalmic preparations, including fixed-combination preparations containing gentamicin and a corticosteroid, during pregnancy only if potential benefits justify potential risks to fetus.101 102 107 108

Lactation

Systemic gentamicin is distributed into milk.140

Discontinue nursing or the drug, taking into account importance of the drug to the woman.107 108

Pediatric Use

Gentamicin ophthalmic ointment or solution: Safety and efficacy not established in neonates.101 102

Fixed-combination ophthalmic preparations containing gentamicin and a corticosteroid (i.e., prednisolone): Safety and efficacy not established in pediatric patients.107 108

Geriatric Use

Fixed-combination ophthalmic preparations containing gentamicin and prednisolone: No overall differences in safety or efficacy relative to younger adults.107 108

Common Adverse Effects

Ocular burning and irritation, nonspecific conjunctivitis, conjunctival epithelial defects, conjunctival hyperemia.101 102

Gentak Pharmacokinetics

Absorption

Extent

Studies in rabbits suggest that gentamicin is absorbed into aqueous humor following topical application of the ophthalmic ointment or solution to the eye; also detected in vitreous humor.a Absorption greatest when cornea is abraded.a

Distribution

Extent

Systemic gentamicin crosses the placenta and is distributed into breast milk.140

Stability

Storage

Ophthalmic

Ointment

Gentamicin 0.3%: 2–30°C.102

Gentamicin 0.3% and prednisolone acetate 0.6%: 15–25°C.107

Solution

Gentamicin 0.3%: 20–25°C; avoid excessive heat.101

Suspension

Gentamicin 0.3% and prednisolone acetate 1%: 15–25°C.108 Do not freeze; protect from excessive heat (≥40°C).108

Actions and Spectrum

  • Aminoglycoside antibiotic obtained from cultures of Micromonospora purpurea.101 102

  • Usually bactericidal.a

  • Mechanism of action not fully elucidated; appears to inhibit protein synthesis in susceptible bacteria by irreversibly binding to 30S ribosomal subunits.a

  • Spectrum of activity of gentamicin includes many aerobic gram-negative and some aerobic gram-positive bacteria.a Inactive against fungi, viruses, and most anaerobic bacteria.a

  • Gram-positive bacteria: Active in vitro against Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae, and S. pyogenes.101 102

  • Gram-negative bacteria: Active in vitro against Haemophilus influenzae, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Neisseria gonorrhoeae, Serratia marcescens, and Pseudomonas aeruginosa.101 102

  • Natural and acquired resistance to gentamicin demonstrated in both gram-negative and gram-positive bacteria.a

  • Partial cross-resistance occurs between gentamicin and other aminoglycosides.a

Advice to Patients

  • Advise patients to avoid contaminating container tip with material from eye, eyelid, or any other source.101 102 Keep container tightly closed when not in use; do not share with others.107 108

  • Advise patients to immediately discontinue gentamicin ophthalmic preparation and contact a clinician if irritation or hypersensitivity occurs.101 102 Also discontinue and contact a clinician if there is an increase in purulent discharge or aggravation of inflammation or pain.101 102

  • Advise patients using fixed-combination ophthalmic preparation containing a corticosteroid to discontinue the drug and contact a clinician if inflammation or pain persists for >48 hours or becomes aggravated.107 108

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.101 102 107 108

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.101 102 107 108

  • Importance of informing patients of other important precautionary information.101 102 107 108 (See Cautions.)

Preparations

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

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Gentamicin Sulfate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Ophthalmic

Ointment

0.3% (of gentamicin)*

Gentak

Akorn

Gentamicin Sulfate Ophthalmic Ointment

Solution

0.3% (of gentamicin)*

Gentak

Akorn

Gentamicin Sulfate Ophthalmic Solution

Gentamicin Sulfate and Prednisolone Acetate

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Ophthalmic

Ointment

Gentamicin Sulfate 0.3% (of gentamicin) and Prednisolone Acetate 0.6%

Pred-G

Allergan

Suspension

Gentamicin Sulfate 0.3% (of gentamicin) and Prednisolone Acetate 1%

Pred-G

Allergan

AHFS DI Essentials™. © Copyright 2018, Selected Revisions October 29, 2018. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

References

101. Akorn, Inc. Gentamicin sulfate ophthalmic solution USP 0.3% prescribing information. Lake Forest, IL; 2016 Jun.

102. Akorn. Gentak (gentamicin sulfate) ophthalmic ointment USP, 0.3% prescribing information. Lake Forest, IL; 2015 Oct.

107. Allergan, Inc. Pred-G (gentamicin and prednisolone acetate) ophthalmic ointment, USP 0.3%/0.6% prescribing information. Irvine, CA; 2017 Mar.

108. Allergan, Inc. Pred-G (gentamicin and prednisolone acetate) ophthalmic suspension, USP 0.3%/1.0% prescribing information. Irvine, CA; 2017 Mar.

135. American Academy of Ophthalmology. Preferred practice pattern (PPP) guidelines: conjunctivitis PPP - 2013. From American Academy of Ophthalmology website. Accessed 20 Dec 2017. http://www.aao.org/preferred-practice-pattern/conjunctivitis-ppp--2013

136. Azari AA, Barney NP. Conjunctivitis: a systematic review of diagnosis and treatment. JAMA. 2013; 310:1721-9. http://www.ncbi.nlm.nih.gov/pubmed/24150468?dopt=AbstractPlus

137. Sheikh A, Hurwitz B, van Schayck CP et al. Antibiotics versus placebo for acute bacterial conjunctivitis. Cochrane Database Syst Rev. 2012; :CD001211. http://www.ncbi.nlm.nih.gov/pubmed/22972049?dopt=AbstractPlus

138. American Academy of Ophthalmology. Preferred Practice Pattern (PPP) guidelines: bacterial keratitis - 2013. From the American Academy of Ophthalmology website. Accessed 5 Dec 2016. https://www.aao.org/preferred-practice-pattern/bacterial-keratitis-ppp--2013

140. Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and lactation, 7th ed. Lippincott Williams & Wilkins: Philadelphia, PA; 2005:720-22.

141. Barnes SD, Kumar NM, Pavin-Langston D et al. Microbial Conjunctivitis. In: Bennett JE, Dolin R, and Blaser MJ, eds. Mandell, Douglas, and Bennett's principles and practices of infectious diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:1392-1401.

a. AHFS drug information 2018. McEvoy, GK, ed. Gentamicin sulfate (ophthalmic). Bethesda, MD: American Society of Health-System Pharmacists; 2018.

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