P&T News: September 1997

Prevention of Bacterial Endocarditis: Update on Recent Changes

Summarized by Joan M. Murhammer, R.Ph.

Peer Review Status: Internally Peer Reviewed by Rachel Miller, M.D.

Summarized from the Recommendations of the American Heart Association¹

Bacterial endocarditis is a rare, yet potentially life-threatening disease and continues to cause substantial morbidity and mortality despite modern antimicrobial and surgical treatments. Therefore, prevention is very important, whenever possible. Bacterial endocarditis can occur when bacteremia develops in individuals with underlying cardiac defects. This bacteremia can occur spontaneously, from a distant focus of infection (e.g., pneumonia, urinary tract infection), or from certain surgical or dental procedures. Prophylactic antibiotics are recommended for patients at risk for developing endocarditis who are undergoing those procedures most likely to produce bacteremia with organisms that commonly cause endocarditis. Prophylaxis is most effective when given pert-procedure in doses that are sufficient to assure adequate antibiotic concentrations in the serum during and after the procedure. The American Heart Association (AMA) has recently updated its recommendations for the prevention of bacterial endocarditis in individuals at risk for this disease. The changes were made to simplify prescribing, improve patient compliance, decrease costs, and reduce the incidence of gastrointestinal adverse drug reactions. The purpose of this publication is to summarize these recommendations.

Major changes in the updated recommendations for determining if prophylaxis is needed include (see JAMA. 1997; 277:1794-801):

• An emphasis that most cases of endocarditis are not attributable to an invasive procedure.
• Cardiac conditions are stratified to three risk categories based on potential -outcome if endocarditis develops. [See Table I of JAMA article, p. 1795.]
• Procedures that may cause bacteremia and require prophylaxis are more clearly specified. [See Tables 2 and 3 of JAMA article, p. 1797.]
• An algorithm to more clearly define when prophylaxis is recommended for patients with mitral valve prolapse (MVP). [See JAMA article, p. 1796.]

Major changes in prophylactic drug regimens include:

Oral. Dental, Respiratory Tract. or Esophageal Procedures (see Table 1)

• The amoxicillin dose was reduced from 3 gm to 2 am, and a follow-up dose is no longer recommended. The previously recommended dose for amoxicillin was 3 gm one hour before the procedure and 1.5 gm six hours after the initial dose. Comparisons of 2 gm versus 3 gm dosing indicate that a 2 gm dose results in adequate serum levels for several hours and causes less gastrointestinal adverse effects. The new recommended dose is 2 am, one hour before the procedure. A second dose is not necessary because of the prolonged serum levels above the minimal inhibitory concentration of most oral streptococci and the prolonged serum inhibitory activity induced by amoxicillin against such strains (6 to 14 hours).
• For patients who are allergic to penicillin, erythromycin is no longer included as an alternative agent because of gastrointestinal upset and complicated pharmacokinetics of the various formulations. The previous recommendation was to administer two doses of either erythromycin or clindamycin in this population. Single doses of clindamycin, cephalexin, azithromycin, or clarithromycin are now the recommended alternative agents in penicillin-allergic patients.
• In patients who are unable to take oral medications, 2 gm of ampicillin IV or IM is recommended 30 minutes before the procedure. In penicillin-allergic patients, either clindamycin 600 mg IV or cefazolin 1 gm IV 30 minutes before the procedure is recommended. Follow-up doses are not recommended. The previous recommendation was to administer clindamycin 300 mg IV before the procedure and either 300 mg IV or 150 mg PO six hours after the procedure. An alternative regimen included two doses of both ampicillin and gentamicin or a single dose of vancomycin for penicillin-allergic patients.

Genitourinary and Gastrointestinal Procedures (see Table 2)

• The prophylactic regimens have been simplified. In high-risk patients, the recommended regimen is two doses of ampicillin and one dose of gentamicin. The second dose can be given as ampicillin IV or amoxicillin PO six hours after the first dose. In penicillin-allergic patients, one dose of vancomycin and gentamicin is recommended, without follow-up doses.
• In moderate-risk patients, recommendations for combination therapy with amoxicillin, ampicillin with gentamicin, or vancomycin with gentamicin have been replaced by a single dose of amoxicillin PO or ampicillin IV (vancomycin if penicillin allergic).

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¹Adapted from JAMA. 1997;277:1794-801. Please call the Pharmacotherapy Evaluation and Consultation Service at 6-2600 if you would like a complete copy of the article.

ALBUTEROL SULFATE Oral Inhaler: 108 mcg per actuation Albuterol sulfate with hydrofluoroalkane propellant (Proventil[R], HFA - Schering) is indicated for the relief of bronchospasm. It utilizes a Spraymiser. device for administration.

NOTE: Due to the markedly increased cost of Proventil[R] HFA over generic albuterol oral inhalers, the prescribing of Proventil[R] HFA is restricted to attending clinical faculty physicians. In addition, according to Pharmacy and Therapeutics Subcommittee actions, prescriptions for albuterol oral inhalers, Proventil[R] oral inhalers, Ventolin[R] oral inhalers, etc., will be filled with generic albuterol oral inhalers unless the prescriber specifies "Proventil[R] HFA."

AZITHROMYCIN Injection: 500 mg Azithromycin injection (Zithromax[R] - Pfizer) is indicated for the treatment of community-acquired pneumonia and pelvic inflammatory disease caused by susceptible organisms. It is dosed once daily.

BECLOMETHASONE Nasal Spray: 0.084% Beclomethasone (Vancenase AQ Double Strength[R] - Schering) aqueous nasal spray is indicated for once daily dosing for the management of seasonal or perennial rhinitis.

BUPROPION Sustained Release Tablets: 100 mg, 150 mg Bupropion sustained-release tablets (Wellbutrin SR[R]) are indicated for the treatment of depression.

CARVEDILOL Tablets: 3.125 mg, 6.25 mg, 12.5 mg, 25 mg Carvedilol (Coreg[R] - SKB) is a nonselective beta-adrenergic blocking agent indicated for the treatment of heart failure in conjunction with digoxin, diuretics and ACE inhibitors.

NOTE: The prescribing of carvedilol is restricted to Cardiology.

DALTEPARIN Injection: 2500 units per 0.2 ml, 5000 units per 0.2 ml Dalteparin (Fragmin[R] - Pharmacia & Upjohn) is a low-molecular weight heparin indicated for prophylaxis against deep vein thrombosis in patients undergoing abdominal surgery who are at risk for developing thromboembolic complications.

DINOPROSTONE Vaginal Insert: 10 mg Dinoprostone (Cervidil[R] - Forest) vaginal inserts are indicated for the initiation and/or continuation of cervical ripening in patients at or near term in whom there is a medical or obstetrical indication for the induction of labor.

IPRATROPIUM Nasal Spray: 0.03%, 0.06% The 0.03% nasal spray (Atrovent[R] - BI) is indicated for the symptomatic relief of allergic and nonallergic perennial rhinitis. The 0.06% spray is indicated for symptomatic relief of rhinorrhea associated with the common cold.

ISOSULFAN BLUE Injection: 1% Isosulfan blue (Lymphazurin[R] - U.S. Surgical) is a dye used to delineate lymphatic vessels.

LEVONORGESTREL PLUS ETHINYL ESTRADIOL Tablets: 0.1 mg plus 0.02 mg This product (Alesse[R] - Wyeth-Ayerst) is an oral contraceptive with a low dose of ethinyl estradiol.

MIDODRINE Tablets: 2.5 mg, 5 mg Midodrine (ProAmatine[R] - Roberts) is indicated for use in patients with symptomatic hypotension whose lives are considerably impaired despite standard treatments.

NOTE: Patients must be carefully monitored for supine hypertension.

RHo (D) IMMUNE GLOBULIN INTRAVENOUS Injection: 600 I.U. (120 mcg), 1500 I.U. (300 mcg) Rho (D) immune globulin (WinRho-SD[R] - North American Biological) is indicated for the treatment of immune thrombocytopenic purpura and for the prevention of maternal transfusion-related Rh isoimmunization.

NOTE: The prescribing of Rho(D) immune globulin intravenous is restricted to Adult and Pediatric Hematology/Oncology.

TRIAMCINOLONE ACETONIDE Nasal Spray: 0.055% Triamcinolone acetonide (NasaCort AQ[R] - Rhone Poulenc Rorer) aqueous nasal spray is indicated for the treatment of seasonal and perennial allergic rhinitis symptoms.

Additional Actions

ALENDRONATE (FOSAMAX.) A 5 mg tablet has been added to stock.

ATORVASTATIN (LIPITOR[R]) A 40 mg tablet has been added to stock.

AZITHROMYCIN TABLETS (ZITHROMAX[R]) The 600 mg strength has been added to stock for the prevention of Mycobacterium avium complex.

DOXYCYCLINE The 50 mg capsule has been added to stock.

LEUPROLIDE ACETATE DEPOT INJECTION The 11.25 mg three-month depot injection (Lupron Depot 3-Month[R]) has been added to stock. This product is indicated for the treatment of endometriosis and uterine leiomyomata.

MULTIVITAMIN WITH ZINC (ADEKS[R]) A chewable tablet has been added to stock. Each tablet contains: vitamin A 4000 I.U.; vitamin D 400 I.U.; vitamin E 150 I.U.; vitamin K 150 mcg; vitamin C 60 mg; folic acid 0.2 mg; thiamine 1.2 mg; riboflavin 1.3 mg; niacin 10 mg; pyridoxine 1.5 mg; vitamin B12 12 mcg; biotin 50 mcg; pantothenic acid 10 mg; zinc 7.5 mg; and beta carotene 3 mg.

MYCOPHENOLATE MOFETIL (CellCept[R]) The 500 mg capsule has been added to stock.

OLANZAPINE (ZYPREXA[R]) A 2.5 mg tablet has been added to stock.

NOTE: The cost following each brief monograph is the UIHC acquisition cost.

Drugs Deleted From Stock

BARIUM SULFATE 56% (ESOPHOTRAST.) CREAM Discontinued by the manufacturer.

BECLOMETHASONE AQUEOUS 0.042% (VANCENASE AQ[R], BECONASE AQ[R]) NASAL SPRAY This product is being replaced with beclomethasone 0.084% (Vancenase AQ Double Strength-) nasal spray.

CLINDAMYCIN 300 MG CAPSULES Deleted due to comparatively high cost; two 150 mg capsules are one-third the cost of a 300 mg capsule.

CORTISONE ACETATE (CORTONE[R]) INJECTION Discontinued by the manufacturer. Hydrocortisone injection is available.

DEXFENFLURAMINE Withdrawn from the market by the manufacturer due to safety concerns.

FENTANYL TRANSMUCOSAL LOZENGES Discontinued due to low use. Fentanyl injection is available.

SILVER NITRATE 1% OPHTHALMIC SOLUTION Discontinued by the manufacturer. Erythromycin ophthalmic ointment is available.

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