Metronidazole Hydrochloride

M

Class: Antiprotozoals, Miscellaneous
VA Class: AM900
CAS Number: 443-48-1
Brands: Flagyl, Helidac Therapy

Carcinogenic in mice and rats.152 156 197 430 495

Avoid unnecessary use; reserve for use in approved indications..152 156 197 430 495 (See Uses.)

Introduction

Antibacterial and antiprotozoal;.152 197 430 494 495 nitroimidazole derivative.494

Uses for Metronidazole Hydrochloride Bone and Joint Infections

Adjunct for treatment of bone and joint infections caused by Bacteroides, including the B. fragilis group (B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron, B. vulgatus).152 197 495

Endocarditis

Treatment of endocarditis caused by Bacteroides (including the B. fragilis group).152 197 495

Gynecologic Infections

Treatment of gynecologic infections (including endometritis, endomyometritis, tubo-ovarian abscess, postsurgical vaginal cuff infection) caused by Bacteroides (including the B. fragilis group), Clostridium, Peptococcus niger, or Peptostreptococcus.152 197 495

Treatment of acute pelvic inflammatory disease (PID); used in conjunction with other anti-infectives.199 341 496 Metronidazole is included in PID regimens to provide coverage against anaerobes.341

When a parenteral regimen is indicated for PID, an initial regimen of IV cefoxitin and IV or oral doxycycline is recommended followed by oral doxycycline; if tubo-ovarian abscess is present, some experts recommend that the oral follow-up regimen include metronidazole (or clindamycin) in addition to doxycycline.341

When an oral regimen is indicated for PID, an single IM dose of ceftriaxone, cefoxitin (with oral probenecid), or cefotaxime is recommended in conjunction with oral doxycycline (with or without oral metronidazole).199 341 496 Alternatively, if a parenteral cephalosporin is not feasible and the community prevalence and individual risk for gonorrhea is low, a regimen of oral levofloxacin or oral ofloxacin (with or without oral metronidazole) may be considered.496

Intra-abdominal Infections

Treatment of intra-abdominal infections (including peritonitis, intra-abdominal abscess, liver abscess) caused by susceptible Bacteroides (including the B. fragilis group), Clostrium, Eubacterium, P. niger, or Peptostreptococcus.152 197 495

Meningitis and Other CNS Infections

Treatment of CNS infections (including meningitis, brain abscess) caused by Bacteroides (including the B. fragilis group).152 197 495

Respiratory Tract Infections

Treatment of respiratory tract infections (including pneumonia) caused by Bacteroides (including the B. fragilis group).152 197 495

Septicemia

Treatment of septicemia caused by Bacteroides (including the B. fragilis group) or Clostridium.152 197 495

Skin and Skin Structure Infections

Treatment of skin and skin structure infections caused by Bacteroides (including the B. fragilis group), Clostridium, Fusobacterium, P. niger, or Peptostreptococcus.152 197 495

Amebiasis

Treatment of acute intestinal amebiasis and amebic liver abscess caused by Entamoeba histolytica.100 152 153 197 364 368 370 Oral metronidazole or oral tinidazole followed by a luminal amebicide (iodoquinol, paromomycin) is the regimen of choice for mild to moderate or severe intestinal disease and for amebic hepatic abscess.100 153 364 368 370

Bacterial Vaginosis

Treatment of bacterial vaginosis (formerly called Haemophilus vaginitis, Gardnerella vaginitis, nonspecific vaginitis, Corynebacterium vaginitis, or anaerobic vaginosis) in pregnant or nonpregnant women.199 292 297 298 302 341 365 366 430

CDC recommends treatment of bacterial vaginosis in all symptomatic women (including pregnant women).341 In addition, asymptomatic pregnant women at high risk for complications of pregnancy should be screened (preferably at the first prenatal visit) and treatment initiated if needed.341

Treatment recommendations for bacterial vaginosis in HIV-infected women are the same as those for women without HIV infection.341

Regimens of choice in nonpregnant women are a 7-day regimen of oral metronidazole, a 5-day regimen of intravaginal metronidazole gel, or a 7-day regimen of intravaginal clindamycin cream;341 alternative regimens are a 7-day regimen of oral clindamycin or 3-day regimen of intravaginal clindamycin suppositories.341 The preferred regimens for pregnant women are a 7-day regimen of oral metronidazole or a 7-day regimen of oral clindamycin.341

Regardless of regimen used, relapse or recurrence is common;287 295 297 298 300 302 307 341 365 an alternative regimen (e.g., topical therapy when oral therapy was used initially) may be used in such situations.297 341

Routine treatment of asymptomatic male sexual contacts of women who have relapsing or recurrent bacterial vaginosis not recommended.341

Balantidiasis

Alternative to tetracycline for treatment of balantidiasis† caused by Balantidium coli.100 153

Blastocystis hominis Infections

Treatment of infections caused by Blastocystis hominis†.100 153 368 371 372 May be effective, but metronidazole resistance may be common.153

Clinical importance of B. hominis as a cause of GI pathology is controversial;100 153 368 371 372 unclear when treatment is indicated.100 368 371 Some clinicians suggest treatment be reserved for certain individuals (e.g., immunocompromised patients) when symptoms persist and no other pathogen or process is found to explain their GI symptoms.100 368

Clostridium difficile-associated Diarrhea and Colitis

Treatment of Clostridium difficile-associated diarrhea and colitis† (CDAD; also known as antibiotic-associated diarrhea and colitis, C. difficile diarrhea, C. difficile colitis, and pseudomembranous colitis).100 125 126 127 128 129 131 132 312 313 314 315 316 344 345 443 444 445 446 447

Drugs of choice are metronidazole and vancomycin; 100 312 313 314 315 316 metronidazole generally preferred and vancomycin reserved for those with severe or potentially life-threatening colitis, patients in whom metronidazole-resistant C. difficile is suspected, patients in whom metronidazole is contraindicated or not tolerated, or those who do not respond to metronidazole.100 126 127 312 313 314 315 316 322 323 406 443 444 445 446 447 448

Crohn’s Disease

Mangement of Crohn’s disease† as an adjunct to conventional therapies.101 102 103 104

Has been used with467 468 471 475 476 477 485 or without ciprofloxacin;101 102 103 104 105 469 470 471 472 473 474 478 479 484 485 486 for induction of remission of mildly to moderately active Crohn’s disease†.101 102 103 104 105 467 468 469 471 472 473 474 475 476 477 478 479 484

Has been used for refractory perianal Crohn’s disease†.102 104 105 470 471 474 478 479 485 486

Dientamoeba fragilis Infections

Treatment of infections caused by Dientamoeba fragilis†.153 Drugs of choice are iodoquinol, paromomycin, tetracycline, or metronidazole.153

Dracunculiasis

Treatment of dracunculiasis† caused by Dracunculus medinensis (guinea worm disease).153

Treatment of choice is slow extraction of worm combined with wound care.153 Metronidazole is not curative, but decreases inflammation and facilitates worm removal.153

Giardiasis

Treatment of giardiasis†.100 153 367 452 Drugs of choice are metronidazole, tinidazole, or nitazoxanide;100 153 367 452 alternatives are paromomycin, furazolidone (no longer commercially available in the US), or quinacrine (not commercially available in the US).100 153 367

Treatment of asymptomatic carriers of giardiasis†.100 367 Treatment of such carriers not generally recommended, except possibly in patients with hypogammaglobulinemia or cystic fibrosis or in an attempt to prevent household transmission of the disease from toddlers to pregnant women.100

Helicobacter pylori Infection and Duodenal Ulcer Disease

Treatment of Helicobacter pylori infection and duodenal ulcer disease (active or a history of duodenal ulcer); eradication of H. pylori has been shown to reduce the risk of duodenal ulcer recurrence.

Used in a multiple-drug regimen that includes metronidazole, tetracycline, and bismuth subsalicylate and a histamine H2-receptor antagonist.455 If initial 14-day regimen does not eradicate H. pylori, a retreatment regimen that does not include metronidazole should be used.455

Nongonococcal Urethritis

Treatment of recurrent and persistent urethritis† in patients with nongonococcal urethritis who have already been treated with a recommended regimen (i.e., azithromycin, doxycycline, erythromycin, ofloxacin or levofloxacin).341

Oral metronidazole or oral tinidazole used in conjunction with oral azithromycin (if azithromycin was not used in the initial regimen) is the regimen recommended by CDC for recurrent and persistent urethritis in patients who were compliant with their initial regimen and have not been re-exposed.341

Rosacea

Treatment of inflammatory lesions (papules and pustules) and erythema associated with rosacea† (acne rosacea).137 139 145 146 148 168 180 181 Topical metronidazole may be preferred to oral metronidazole.137 181

Tetanus

Adjunct in treatment of tetanus caused by C. tetani.100 489

Trichomoniasis

Treatment of symptomatic and asymptomatic trichomoniasis when Trichomonas vaginalis has been demonstrated by an appropriate diagnostic procedure (e.g., wet smear and/or culture, OSOM Trichomonas Rapid Test, Affirm VP III).100 152 153 197 199 297 298 302 337 338 339 341

Drug of choice is metronidazole or tinidazole.100 153 199 297 302 337 338 339 341 Goal of treatment is to provide symptomatic relief, achieve microbiologic cure, and reduce transmission; to achieve this goal, both the index patient and sexual (particularly steady) partner(s) should be treated.153 199 297 302 339 341

If treatment failure occurs with initial metronidazole treatment and reinfection is excluded, alternative regimens using metronidazole or tinidazole can be used.153 199 341 If retreatment is ineffective, consultation with an expert (available through CDC) is recommended.341

Perioperative Prophylaxis

Perioperative prophylaxis to reduce the incidence of postoperative anaerobic bacterial infections in patients undergoing colorectal surgery.109 110 111 112 156 495 Preferred regimens are IV cefoxitin alone; IV cefazolin and IV metronidazole; oral erythromycin and oral neomycin; or oral metronidazole and oral neomycin.110 112 490

Perioperative prophylaxis in patients undergoing appendectomy†;109 111 110 112 113 used in conjunction with cefazolin.110 Preferred regimens for appendectomy (nonperforated) are IV cefoxitin alone or IV cefazolin and IV metronidazole.110

Prophylaxis in Sexual Assault Victims

Empiric anti-infective prophylaxis in sexual assault victims†; used in conjunction with IM ceftriaxone and oral azithromycin or doxycycline.199 341

Metronidazole Hydrochloride Dosage and Administration Administration

Administer orally152 197 430 or by continuous or intermittent IV infusion.156 495 Do not administer by rapid IV injection because of the low pH of the reconstituted product.156 495

In the treatment of serious anaerobic infections, parenteral route usually is used initially and oral metronidazole substituted when warranted by patient’s condition.152 197

Oral Administration

Administer extended-release tablets at least 1 hour before or 2 hours after meals.430

IV Infusion

For solution and drug compatibility information, see Compatibility under Stability.

Commercially available metronidazole injection for IV infusion does not need to be diluted or neutralized prior to IV administration.156 495

Metronidazole hydrochloride powder for injection must by reconstituted, diluted, and then neutralized prior to IV administration.156

Reconstitution and Dilution

Reconstitute metronidazole hydrochloride powder for injection by adding 4.4 mL of sterile or bacteriostatic water for injection, 0.9% sodium chloride injection, or bacteriostatic sodium chloride injection to the vial containing 500 mg of metronidazole.156 The reconstituted solution contains approximately 100 mg of metronidazole/mL and has a pH of 0.5–2.156

The reconstituted metronidazole hydrochloride solution must be further diluted with 0.9% sodium chloride injection, 5% dextrose injection, or lactated Ringer’s injection to a concentration of ?8 mg/mL.156

The reconstituted and diluted metronidazole hydrochloride solution must then be neutralized by adding approximately 5 mEq of sodium bicarbonate injection for each 500 mg of metronidazole.156 The addition of sodium bicarbonate to the metronidazole hydrochloride solution may generate carbon dioxide gas and it may be necessary to relieve gas pressure in the container.156

Rate of Administration

IV infusions usually are infused over 1 hour.156 495

Dosage

Available as metronidazole152 156 197 430 495 and metronidazole hydrochloride;156 dosage expressed in terms of metronidazole.156

Pediatric Patients General Dosage in Neonates† Oral or IV

Neonates <1 week of age: AAP recommends 7.5 mg/kg every 24–48 hours in those weighing <1.2 g, 7.5 mg/kg every 24 hours in those weighing 1.2–2 kg, or 7.5 mg/kg every 12 hours in those weighing >2 kg.100

Neonates 1–4 weeks of age: AAP recommends 7.5 mg/kg every 24–48 hours in those weighing <1.2 kg, 7.5 mg/kg every 12 hours in those weighing 1.2–2 kg, and 15 mg/kg every 12 hours in those weighing >2 kg.100

General Dosage in Children ?1 Month of Age† Oral

15–35 mg/kg daily in 3 divided doses.100 AAP states oral route inappropriate for severe infections.100

Amebiasis Entamoeba histolytica Infections Oral

35–50 mg/kg daily in 3 divided doses given for 7–10 (usually 10) days;152 153 197 370 follow-up with a luminal amebicide (e.g., iodoquinol, paromomycin).153

Bacterial Vaginosis† Oral

Children weighing <45 kg: 15 mg/kg daily (up to 1 g) in 2 divided doses given for 7 days.100

Adolescents: 500 mg twice daily for 7 days.100

Balantidiasis† Oral

35–50 mg/kg daily in 3 divided doses given for 5 days.153

Blastocystis hominis Infections† Oral

20–35 mg/kg daily in 3 divided doses given for 10 days may improve symptoms in some patients.100

Crohn’s Disease† Oral

10–20 mg/kg daily (up to 1 g daily) has been recommended for children with mild perianal Crohn’s disease† or those intolerant to sulfasalazine or mesalamine.487

Clostridium difficile-associated Diarrhea and Colitis† Oral

30–50 mg/kg daily in 3 or 4 equally divided doses given for 7–10 days (not to exceed adult dosage).100 445 446

Dientamoeba fragilis Infections† Oral

20–40 mg/kg daily in 3 divided doses given for 10 days.153

Dracunculiasis† Oral

25 mg/kg daily (up to 750 mg) in 3 divided doses given for 10 days.153 Is not curative, but may decrease inflammation and facilitate worm removal.153

Giardiasis† Oral

15 mg/kg daily in 3 divided doses given for 5–7 days.153 367 452

Nongonococcal Urethritis† Oral

Recurrent or persistent urethritis in adolescents: A single 2-g dose given in conjunction with a single 1-g dose of oral azithromycin (if azithromycin not used in the initial regimen).341

Tetanus† Oral

30 mg/kg daily (up to 4 g daily) in 4 doses given for 10–14 days.100

IV

30 mg/kg daily (up to 4 g daily) in 4 doses given for 10–14 days.100

Trichomoniasis† Oral

Prepubertal children weighing <45 kg: 15 mg/kg daily in 3 divided doses (up to 2 g daily) given for 7 days.100 153

Adolescents: A single 2-g dose or 500 mg twice daily for 7 days.100

Prophylaxis in Sexual Assault Victims† Oral

Preadolescent children weighing <45 kg: 15 mg/kg daily given in 3 divided doses for 7 days given in conjunction with IM ceftriaxone and either oral azithromycin or oral erythromycin.100 341

Adolescents and preadolescent children weighing ?45 kg: A single 2-g dose given in conjunction with IM ceftriaxone and either oral azithromycin or oral doxycycline.100 341

Adults Anaerobic Bacterial Infections Serious Infections Oral

7.5 mg/kg every 6 hours (up to 4 g daily).152 156 197

IV, then Oral

An initial IV loading dose of 15 mg/kg followed by IV maintenance doses of 7.5 mg/kg every 6 hours.156 495 After clinical improvement occurs, switch to oral metronidazole (7.5 mg/kg every 6 hours).156 495

Total duration of treatment usually is 7–10 days, but infections of bone and joints, lower respiratory tract, or endocardium may require longer treatment.156 495

Gynecologic Infections Pelvic Inflammatory Disease Oral

500 mg twice daily given for 14 days; used in conjunction with a single IM dose of ceftriaxone (250 mg), cefoxitin (2 g with oral probenecid 1 g), or another parenteral cephalosporin (e.g., cefotaxime) and 14-day regimen of oral doxycycline (100 mg twice daily).341 496

Alternatively, 500 mg twice daily given for 14 days; used in conjunction with a 14-day regimen of oral ofloxacin (400 mg twice daily) or levofloxacin (500 mg once daily).199 341 496 Regimens containing a fluoroquinolone should only be considered when a parenteral cephalosporin is not feasible and the community prevalence and individual risk of gonorrhea is low.496

Amebiasis Entamoeba histolytic Infections Oral

750 mg 3 times daily given for 5–10 (usually 10) days for intestinal amebiasis152 153 197 364 368 370 or 500–750 mg 3 times daily given for 5–10 (usually 10) days for amebic liver abscess.152 197 364 368 370 Alternatively, amebic liver abscess has been treated with 2.4 g once daily given for 1 or 2 days.364

Follow-up with a luminal amebicide (e.g., iodoquinol, paromomycin) after metronidazole.153 364 368 370

IV

500 mg every 6 hours for 10 days.364

Bacterial Vaginosis Nonpregnant Women Oral

Conventional tablets: 500 mg twice daily given for 7 days.100 199 286 297 298 300 301 302 341 366 A single 2-g dose has been used (e.g., for patients who may be noncompliant with the multiple-dose regimen),120 122 199 292 297 but appears to be less effective than other regimens and is no longer recommended by CDC.341

Extended-release tablets: 750 mg once daily given for 7 days.199 341 416 417 430

Pregnant Women Oral

Conventional tablets: 500 mg twice daily or 250 mg 3 times daily given for 7 days.341 416 417

Contraindicated during first trimester of pregnancy.152 197 430 In addition, single-dose regimens not recommended in pregnant women because of the slightly higher serum concentrations attained, which may reach fetal circulation.152

Balantidiasis† Oral

750 mg 3 times daily given for 5 days.153

Blastocystis hominis Infections† Oral

750 mg 3 times daily given for 10 days may improve symptoms in some patients.100 153

Crohn’s Disease† Oral

400 mg twice daily101 103 105 or 1 g daily has been effective for treatment of active Crohn’s disease†.467 472 473 475 476 482 For treatment of refractory perineal disease, 20 mg/kg (1–1.5 g) given in 3–5 divided doses daily has been employed.102 103 104 105 478 486

Clostridium difficile-associated Diarrhea and Colitis† Oral

750 mg to 2 g daily in 3 or 4 divided doses given for 7–14 days.125 126 129 131 132 133 313 314

Dose-ranging studies to determine comparative efficacy have not been performed; most commonly employed regimens are 250 mg 4 times daily or 500 mg 3 times daily given for 10 days.443 444 445 446

IV

500–750 mg every 6–8 hours; use when oral therapy is not feasible.134 161 162 313 342 343 445

Dientamoeba fragilis Infections† Oral

500–750 mg 3 times daily given for 10 days.153

Dracunculiasis† Oral

250 mg 3 times daily given for 10 days.153 Is not curative, but may decrease inflammation and facilitate worm removal.153

Giardiasis† Oral

250 mg 3 times daily given for 5–7 days.153 367 452

Helicobacter pylori Infection and Duodenal Ulcer Disease Oral

250 mg in conjunction with tetracycline (500 mg) and bismuth subsalicylate (525 mg) 4 times daily (at meals and at bedtime) for 14 days; these drugs should be given concomitantly with an H2-receptor antagonist in recommended dosage.455

Nongonococcal Urethritis† Oral

Recurrent or persistent urethritis: A single 2-g dose given in conjunction with a single 1-g dose of oral azithromycin (if azithromycin not used in the initial regimen).341

Tetanus† IV

500 mg every 6 hours given for 7–10 days.489

Trichomoniasis Initial Treatment Oral

2 g as a single dose152 153 199 341 or in 2 divided doses.152 Alternatively, 500 mg twice daily given for 7 days153 199 341 or 375 mg twice daily given for 7 days.199 197 Manufacturer also recommends 250 mg 3 times daily given for 7 days.152

Retreatment Oral

500 mg twice daily given for 7 days.297 341 If repeated failure occurs, CDC recommends 2 g once daily given for 5 days.297 341 Others recommend retreatment with 2–4 g daily for 7–14 days if metronidazole-resistant strains are involved.153 199

Do not administer repeat courses of treatment unless presence of T. vaginalis is confirmed by wet smear and/or culture and an interval of 4–6 weeks has passed since the initial course.152 197

If treatment of resistant infection is guided by in vitro susceptibility testing under aerobic conditions, some clinicians recommend that T. vaginalis strains exhibiting low-level resistance (minimum lethal concentration [MLC] <100 mcg/mL) be treated with 2 g daily for 3–5 days, those with moderate (intermediate) resistance (MLC 100–200 mcg/mL) be treated with 2–2.5 g daily for 7–10 days, and those with high-level resistance (MLC >200 mcg/mL) be treated with 3–3.5 g daily for 14–21 days.124 302 338 340 Because strains with high-level resistance are difficult to treat,124 297 302 338 340 CDC recommends that patients with culture-documented infection who do not respond to repeat regimens at dosages up to 2 g daily for 3–5 days and in whom the possibility of reinfection has been excluded should be managed in consultation with an expert (available through CDC).297 341

Perioperative Prophylaxis Colorectal Surgery IV

0.5 g given at induction of anesthesia (within 0.5–1 hour prior to incision); used in conjunction with IV cefazolin (1–2 g).110

Manufacturer recommends 15 mg/kg by IV infusion over 30–60 minutes 1 hour prior to the procedure and, if necessary, 7.5 mg/kg by IV infusion over 30–60 minutes at 6 and 12 hours after the initial dose.156 495 The initial preoperative dose must be completely infused approximately 1 hour prior to surgery to ensure adequate serum and tissue concentrations of metronidazole at the time of incision.156 495 Prophylactic use of metronidazole should be limited to the day of surgery and should not be continued for more than 12 hours after surgery.156 495

Oral

2 g with oral neomycin sulfate (2 g) given at 7 p.m. and 11 p.m. on day before surgery; used in conjunction with appropriate diet and catharsis.110

Prophylaxis in Sexual Assault Victims† Oral

A single 2-g dose given in conjunction with IM ceftriaxone and either oral azithromycin or oral doxycycline.100 341

Special Populations Hepatic Impairment

Decrease dosage in patients with severe hepatic impairment and monitor plasma concentrations of the drug.152 156 160 197 430 495

Geriatric Patients

Select dosage with caution because of age-related decreases in hepatic function.152 197 430

Cautions for Metronidazole Hydrochloride Contraindications

Hypersensitivity to metronidazole or other nitroimidazole derivatives.152 156 197 430 495 Cautious desensitization has been used in some situations when use of metronidazole was considered necessary.341 436 (See Hypersensitivity Reactions and Desensitization under Cautions.)

First trimester of pregnancy.152 197 430

Helidac Therapy (kit containing tetracycline, metronidazole, bismuth subsalicylate) contraindicated in pregnant or nursing women, pediatric patients, patients with hepatic or renal impairment, patients with known allergy to aspirin or salicylates, and those with known hypersensitivity to any component of the kit.455

Warnings/Precautions Warnings Seizures and Peripheral Neuropathy

Seizures and peripheral neuropathy (characterized by numbness or paresthesia of an extremity) reported with metronidazole.152 156 197 430 495

Persistent peripheral neuropathy reported in some patients receiving prolonged therapy.430 If abnormal neurologic signs develop, promptly discontinue drug..152 156 197 430

Use with caution in those with CNS diseases.152 197 430

Sensitivity Reactions Hypersensitivity Reactions and Desensitization

Hypersensitivity reactions, including urticaria, pruritus, erythematous rash, flushing, nasal congestion, fever, and fleeting joint pains sometimes resembling serum sickness, have been reported with metronidazole.152 156 197 430 495

Because there are no effective alternatives to metronidazole in the US for treatment of trichomoniasis, CDC states that desensitization can be attempted in patients with metronidazole hypersensitivity.341 The possibility that desensitization may be hazardous should be considered435 and adequate procedures (e.g., established IV access, BP monitoring) and therapies (e.g., epinephrine, corticosteroids, antihistamines, oxygen) for management of an acute hypersensitivity reaction should be readily available.435 Pretreatment (e.g., with an antihistamine and/or corticosteroid) also should be considered.435

Desensitization has been performed by administering increasing doses of IV metronidazole incrementally until a therapeutic dose was achieved, at which time oral dosing was initiated.435 In this regimen, an initial 5-mcg dose of IV metronidazole was given and the dose increased at 15- to 20-minute intervals to 15, 50, 150, and 500 mcg and then to 1.5, 5, 15, 30, 60, and 125 mg.435 After the 125-mg IV dose, dosing was switched to oral metronidazole and doses of 250, 500, and 2 g were given at 1-hour intervals.435 For trichomoniasis, desensitization dosing can be stopped after the 2-g dose.435 Patient should be monitored for ?4 hours after the last dose (24 hours if there was any evidence of a reaction).435

General Precautions Selection and Use of Anti-infectives

To reduce development of drug-resistant bacteria and maintain effectiveness of metronidazole and other antibacterials, use only for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.152 197 430 495

When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing.152 197 430 495 In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.152 197 430 495

Surgical procedures should be performed in conjunction with metronidazole therapy when indicated.152 156 197 430 495

In mixed aerobic and anaerobic infections, anti-infectives appropriate for treatment of aerobic bacteria should be used in conjunction with metronidazole.152 156 197 430 495

History of Blood Dyscrasia

Use with caution in patients with evidence or history of blood dyscrasias.152 156

Metronidazole Hydrochloride

.