Aztreonam

Class: Monobactams
Chemical Name: [2S - [2α,3β(Z)]] - 2 - [[[1 - (2 - Amino - 4 - thiazolyl) - 2 - [2 - methyl - 4 - oxo - 1 - sulfo - 3 - azetidinyl)amino] - 2 - oxoethylidene]amino]oxy] - 2 - methylpropanoic acid
CAS Number: 78110-38-0
Brands: Azactam

Introduction

Antibacterial; monocyclic β-lactam antibiotic; monobactam.^{1 42 43 44 246}

Uses for Aztreonam

Bone and Joint Infections

Has been used for treatment of bone and joint infections† (including osteomyelitis or septic arthritis) caused by susceptible Enterobacter, Escherichia coli, Haemophilus influenzae, Klebsiella, Proteus mirabilis, Pseudomonas aeruginosa, or Serratia marcescens.^{48 166 172 173 177 178 220 267 268 282}

If gram-positive bacteria are known or suspected to also be present, an antistaphylococcal anti-infective (e.g., penicillinase-resistant penicillin, vancomycin) should be used concomitantly.¹⁷⁷

Gynecologic Infections

Treatment of gynecologic infections (including endometritis and pelvic cellulitis) caused by susceptible Enterobacter (including E. cloacae), E. coli, K. pneumoniae, or P. mirabilis.^{a 171 173 183 192 211}

Should not be used alone for empiric treatment of gynecologic infections since these usually are polymicrobial and frequently are mixed aerobic-anaerobic bacterial infections.^{171 173 183 211} Clindamycin or metronidazole generally used concomitantly if aztreonam is used for initial treatment of gynecologic infections.^{171 173 177 183 211 213 214 267}

Intra-abdominal Infections

Treatment of intra-abdominal infections (including peritonitis) caused by susceptible Citrobacter (including C. freundii), Enterobacter (including E. cloacae), E. coli, Klebsiella (including K. pneumoniae), Ps. aeruginosa, or Serratia (including S. marcescens).^{a 173 177 213 214}

Should not be used alone for empiric treatment of intra-abdominal infections since these infections usually are polymicrobial and frequently are mixed aerobic-anaerobic bacterial infections.^{173 213 214} Clindamycin or metronidazole generally used concomitantly if aztreonam is used for initial treatment of intra-abdominal infections.^{173 177 213 214}

Respiratory Tract Infections

Treatment of lower respiratory tract infections (including pneumonia and bronchitis) caused by susceptible Enterobacter, E. coli, H. influenzae, K. pneumoniae, Ps. aeruginosa, P. mirabilis, or S. marcescens.^{a 165 167 168 169 173 176 177 192 206 208 222}

Also has been used for treatment of lower respiratory tract infections caused by susceptible Citrobacter†,^{167 168 176 206 208 264 267} Hafnia†,²⁶⁴ K. oxytoca†,¹⁶⁸ Morganella†,^{206 208 264} P. vulgaris†,¹⁶⁵ P. stuartii†,¹⁹² or Moraxella catarrhalis†.^{165 208 264}

Should not be used alone for empiric treatment of lower respiratory tract infections since these infections frequently are caused by gram-positive and/or anaerobic bacteria.^{1 48 164 165 176 186 202 206 208 223 235 241 264 266 268}

A combination regimen of clindamycin and aztreonam has been used for initial empiric treatment of lower respiratory tract infections (especially nosocomial infections).^{165 167 206 235 264 268} ATS has suggested a regimen of aztreonam and clindamycin as an alternative regimen for empiric treatment of nosocomial pneumonia in patients hypersensitive to β-lactam anti-infectives²⁹⁷ and has recommended a combination regimen of aztreonam and an aminoglycoside as one of several possible empiric regimens for patients with nosocomial pneumonia when Ps. aeruginosa or Acinetobacter may be involved (vancomycin should be added if oxacillin-resistant [methicillin-resistant] staphylococci are suspected).²⁹⁷

For empiric treatment of community-acquired pneumonia (CAP) in patients at risk for Ps. aeruginosa infection who are hypersensitive to β-lactam anti-infectives, ATS has suggested a regimen of aztreonam, an aminoglycoside, and an IV fluoroquinolone active against Streptococcus pneumoniae.²⁵⁰

Septicemia

Treatment of septicemia caused by susceptible Enterobacter, E. coli, K. pneumoniae, Ps. aeruginosa, P. mirabilis, or S. marcescens.^{a 173 176 177 186 192 221 222 223}

Also has been used for treatment of septicemia caused by susceptible Citrobacter†^{264 267} or H. influenzae†.^{186 192 264}

Skin and Skin Structure Infections

Treatment of skin and skin structure infections (including those associated with postoperative wounds, ulcers, and burns) caused by susceptible Citrobacter, Enterobacter, E. coli, K. pneumoniae, P. mirabilis, Ps. aeruginosa, or S. marcescens.^{a 173 177 192 222 223}

Adjunct to surgery in management of abscesses, cutaneous infections, infections complicating hollow viscus perforations, or infections of serous surfaces caused by susceptible gram-negative aerobic bacteria.^{1 264}

Urinary Tract Infections (UTIs)

Treatment of uncomplicated or complicated UTIs (including pyelonephritis and initial or recurrent cystitis) caused by susceptible Citrobacter, E. cloacae, E. coli, K. pneumoniae, K. oxytoca, P. mirabilis, Ps. aeruginosa, or S. marcescens.^{a 90 160 162 170 175 176 177 190 192 218 219 223}

Also has been used for treatment of UTIs caused by susceptible E. aerogenes†,^{176 218} Morganella morganii†,^{176 218 264 267} P. vulgaris†,²¹⁸ or Providencia†.^{177 218 264}

Has been effective for treatment of cystitis or pyelonephritis caused by gram-negative aerobic bacteria resistant to aminopenicillins, first or second generation cephalosporins, and/or aminoglycosides.^{170 218 264} Although aztreonam generally is associated with less toxicity than aminoglycosides, colonization or superinfection with gram-positive bacteria (especially Enterococcus faecalis) has been reported more frequently with aztreonam than with aminoglycosides.^{46 90 160 164 175 188}

Gonorrhea

Has been effective for treatment of uncomplicated urethral, endocervical, anorectal, and/or pharyngeal gonorrhea† caused by penicillinase- or nonpenicillinase-producing Neisseria gonorrhoeae.^{48 101 173 197 236} Not included in current CDC recommendations for treatment of gonorrhea.²⁸⁴

Empiric Therapy in Febrile Neutropenic Patients

Has been used in conjunction with vancomycin (with or without amikacin) for empiric anti-infective therapy in febrile granulocytopenic adults†.^{180 216} Because gram-positive bacteria (especially Staphylococcus epidermidis) are being reported with increasing frequency in febrile granulocytopenic patients and because aztreonam is inactive against these organisms, an anti-infective agent active against staphylococci (e.g., vancomycin) also should be used if aztreonam is used for empiric therapy in these patients.^{215 268 298} A regimen of aztreonam and vancomycin is considered an alternative empiric regimen in patients hypersensitive to penicillins and cephalosporins.²⁹⁸

Consult published protocols for the treatment of infections in febrile neutropenic patients for specific recommendations regarding selection of the initial empiric regimen, when to change the initial regimen, possible subsequent regimens, and duration of therapy in these patients.²⁹⁹ Consultation with an infectious disease expert knowledgeable about infections in immunocompromised patients also is advised.²⁹⁹

Aztreonam Dosage and Administration

Administration

Administer by IV injection or infusion or by deep IM injection.¹ Has been administered intraperitoneally† in dialysis fluid.^{56 196 227}

IV route preferred in patients with septicemia, localized parenchymal abscess (such as intra-abdominal abscess), peritonitis, or other severe systemic or life-threatening infection and when individual doses >1 g are to be administered.¹

The commercially available frozen aztreonam injection in dextrose should be used only for IV infusion.²⁸⁷

IV Injection

Reconstitution

For direct intermittent IV injection, reconstitute vials containing 500 mg, 1 g, or 2 g by adding 6–10 mL of sterile water for injection.¹ Shake immediately and vigorously following addition of the diluent.¹

Rate of Administration

Inject appropriate dose of reconstituted solution slowly over a period of 3–5 minutes either directly into a vein or into the tubing of a compatible IV solution.¹

IV Infusion

When given IV via a common administration tubing used to administer another drug, especially one that is incompatible with aztreonam, the tubing should be flushed before and after aztreonam administration with an IV infusion solution compatible with both drugs; the drugs should not be given simultaneously.^{1 264 276} When a Y-type IV administration set is used, careful attention should be given to the calculated volume of aztreonam solution to ensure that the entire dose is infused.^{1 264}

Reconstitution and Dilution

For intermittent IV infusion, a 100-mL bottle containing 500 mg, 1 g, or 2 g of aztreonam may be reconstituted with a compatible IV infusion solution to provide a final concentration not exceeding 20 mg/mL; each g of aztreonam should be reconstituted with ≥50 mL of compatible IV infusion solution.¹ Alternatively, a vial containing 500 mg, 1 g, or 2 g of aztreonam may be initially reconstituted using ≥3 mL of sterile water for injection per g of drug and then diluted further by adding the reconstituted solution to a compatible IV infusion solution¹ to provide a solution with a final concentration not exceeding 20 mg/mL.¹ Shake immediately and vigorously following addition of the diluent.¹ A volume control IV administration set may be used to add the appropriate dose of the initially reconstituted aztreonam solution to the compatible IV infusion solution during administration; this final dilution should provide a solution with a concentration of ≤20 mg/mL.¹

Thaw the commercially available injection (frozen) at room temperature or in a refrigerator; do not force thaw by immersion in a water bath or by exposure to microwave radiation.²⁸⁷ A precipitate may have formed in the frozen injection, but should dissolve with little or no agitation after reaching room temperature.²⁸⁷ Discard thawed injection if an insoluble precipitate is present or if container seals or outlet ports are not intact.²⁸⁷ The injection should not be used in series connections with other plastic containers, since such use could result in air embolism from residual air being drawn from the primary container before administration of fluid from the secondary container is complete.²⁸⁷ Manufacturer recommends that the IV administration set be replaced every 48 hours.²⁸⁷

Rate of Administration

Give by IV infusion over 20–60 minutes.^{1 160 161 164 165 175 177 186 280}

IM Administration

Inject appropriate dose of reconstituted IM solution deeply into a large muscle, such as the upper outer quadrant of the gluteus maximus or lateral part of the thigh, using usual techniques and precautions.^{1 264}

Generally well tolerated when given IM; should not be admixed with local anesthetic agents.^{1 264}

Reconstitution

Prepare IM solutions by reconstituting vial containing 500 mg, 1 g, or 2 g with sterile water for injection, 0.9% sodium chloride injection, bacteriostatic water for injection (with benzyl alcohol or parabens), or bacteriostatic sodium chloride injection (with benzyl alcohol).¹ Use ≥3 mL of diluent per g of aztreonam.¹ Shake immediately and vigorously following addition of the diluent.¹

Dosage

Dosage and route of administration should be determined by the type and severity of infection, susceptibility of the causative organism, and condition of the patient.^{1 48} Dosages lower than those usually recommended should not be used.¹

Pediatric Patients

General Dosage for Neonates†

IV or IM

Neonates <1 week of age†: AAP recommends 30 mg/kg every 12 hours in those weighing ≤2 kg or 30 mg/kg every 8 hours in those weighing >2 kg.³⁰⁰

Neonates 1–4 weeks of age†: AAP recommends 30 mg/kg every 12 hours in those weighing <1.2 kg, 30 mg/kg every 8 hours in those weighing 1.2–2 kg, or 30 mg/kg every 6 hours in those weighing >2 kg.³⁰⁰

General Pediatric Dosage

IV

Children ≥9 months of age: Manufacturer recommends 30 mg/kg every 8 hours for treatment of mild to moderate infections or 30 mg/kg every 6 or 8 hours for treatment of moderate to severe infections.¹

Children >1 month of age†: AAP recommends 90 mg/kg daily given in 3 divided doses for mild to moderate infections or 120 mg/kg daily given in 4 divided doses for severe infections.³⁰⁰

Children with cystic fibrosis: A dosage of 50 mg/kg every 6 or 8 hours (i.e., 150–200 mg/kg daily) has been suggested.^{269 270 275 276 280}

IM

Children >1 month of age†: AAP recommends 90 mg/kg daily given in 3 divided doses for mild to moderate infections or 120 mg/kg daily given in 4 divided doses for severe infections.³⁰⁰

Adults

General Adult Dosage

Moderately Severe Systemic Infections

IV

1 or 2 g every 8 or 12 hours.^{1 166 168 173 176 177 208 211 221 222 223 267}

IM

1 g every 8 or 12 hours.^{1 166 168 173 176 177 208 211 221 222 223 267}

Severe Systemic or Life-threatening Infections

IV

2 g every 6 or 8 hours.^{1 168 173 208 267}

Urinary Tract Infections (UTIs)

IV or IM

500 mg or 1 g every 8 or 12 hours.^{1 160 161 162 163 164 165 177 186 190 267}

Uncomplicated UTIs usually treated for 5–10 days;^{160 190} complicated UTIs usually treated for ≥10–18 days.^{160 162 164 165}

Prescribing Limits

Pediatric Patients

Treatment of Infections

IV

Maximum recommended in pediatric patients ≥9 months of age is 120 mg/kg daily, but higher dosage may be warranted in those with cystic fibrosis.¹

Adults

Treatment of Infections

IV or IM

Maximum 8 g daily.¹

Special Populations

Hepatic Impairment

Treatment of Infections

IV or IM

Only limited experience with use of aztreonam in patients with impaired hepatic function.²⁶⁴

Some clinicians recommend that dosage be decreased by 20–25% in patients with alcoholic cirrhosis, especially if long-term therapy with the drug is required;^{32 46 47} others suggest that this decrease in dosage is unnecessary unless renal function also is impaired.^{276 277}

Modification of usual dosage probably unnecessary in patients with stable primary biliary cirrhosis or other chronic hepatic disease unless renal function also is impaired.^{2 32 56 276}

Renal Impairment

Treatment of Infections

IV or IM

Doses and/or frequency of administration in adults with Cl_cr ≤30 mL/minute should be modified in response to the degree of renal impairment.^{1 2 11 30 33 46 47 48 56 203 227 256 264}

Serum creatinine concentrations alone may not be sufficiently accurate to assess the degree of renal impairment, especially in geriatric adults; dosage preferably should be based on the patient’s measured or estimated Cl_cr.¹

Adults with Cl_cr 10–30 mL/minute per 1.73 m²: 1- or 2-g loading dose followed by maintenance doses equal to one-half the usual dose (i.e., 250 mg, 500 mg, or 1 g) given at the usual dosage intervals.^{1 48 56 264}

Adults with Cl_cr <10 mL/minute per 1.73 m²: A loading dose equal to the usual dose (i.e., 500 mg, 1 g, or 2 g) followed by maintenance doses equal to one-fourth the usual dose (i.e., 125 mg, 250 mg, or 500 mg) given at the usual dosage intervals.^{1 36 48 56 264}

Adults undergoing hemodialysis: A loading dose equal to the usual dose (i.e., 500 mg, 1 g, or 2 g) followed by maintenance doses equal to one-fourth the usual dose (i.e., 125 mg, 250 mg, or 500 mg) given at the usual dosage intervals.^{1 36 48 56 264} Those with serious or life-threatening infections also should receive a supplemental dose equal to one-eighth the initial dose (i.e., 62.5 mg, 125 mg, or 250 mg) given immediately after each dialysis period.^{1 30 36 46 56 264 276 277}

Adults undergoing CAPD: Some clinicians suggest that those with systemic infections should receive a loading dose equal to the usual dose (i.e., 500 mg, 1 g, or 2 g) followed by maintenance doses equal to one-fourth the usual dose (i.e., 125 mg, 250 mg, or 500 mg) given at the usual dosage intervals.^{36 46 48 227} Some clinicians suggest that adults undergoing CAPD who have peritonitis caused by susceptible organisms may receive a 1-g IV loading dose followed by maintenance doses of 500 mg given intraperitoneally† in 2 L of dialysate every 6 hours.^{36 46 227}

Data insufficient to date to make dosage recommendations for pediatric patients with impaired renal function.¹

Geriatric Patients

Select dosage based on renal function.^{1 14 264 266} (See Renal Impairment under Dosage and Administration.)

Select dosage with caution because of age-related decreases in renal impairment.¹

Cautions for Aztreonam

Contraindications

• 
  

  Hypersensitivity to aztreonam or any component in the formulation.¹

  
  

Warnings/Precautions

Warnings

Superinfection/Clostridium difficile-associated Colitis

Possible emergence and overgrowth of nonsusceptible bacteria (e.g., Staphylococcus aureus, Enterococcus faecalis) or fungi.¹ Institute appropriate therapy if superinfection occurs.¹

Treatment with anti-infectives may permit overgrowth of clostridia.¹ Consider Clostridium difficile-associated diarrhea and colitis (antibiotic-associated pseudomembranous colitis) if diarrhea develops and manage accordingly.¹

Some mild cases of C. difficile-associated diarrhea and colitis may respond to discontinuance alone.^{1 301 302 303 304 305} Manage moderate to severe cases with fluid, electrolyte, and protein supplementation; appropriate anti-infective therapy (e.g., oral metronidazole or vancomycin) recommended if colitis is severe.^{1 301 302 303 304 305}

Sensitivity Reactions

Hypersensitivity Reactions

Immediate hypersensitivity reactions, including anaphylaxis,^{1 264} bronchospasm,²⁶⁴ generalized urticaria with or without palpebral and lingual edema and respiratory impairment,^{290 295 296} and a severe episode of shock, rash, and eosinophilia,¹⁷⁵ have been reported.^{1 175 264}

Toxic epidermal necrolysis reported rarely in patients receiving aztreonam who were undergoing bone marrow transplant and had multiple risk factors (e.g., sepsis, radiation therapy, concomitant treatment with drugs associated with toxic epidermal necrolysis).¹

If hypersensitivity reaction occurs, discontinue aztreonam and initiate appropriate supportive treatment (e.g., vasopressors, antihistamines, corticosteroids, maintenance of ventilation).^{1 264} Serious hypersensitivity reactions may require epinephrine and other emergency measures.^{1 264}

Cross-Hypersensitivity

Partial cross-allergenicity occurs among bicyclic β-lactam antibiotics (e.g., penicillins, cephalosporins, cephamycins).^{151 157 243 248 263 289} Although there appears to be little cross-allergenicity between aztreonam and bicyclic β-lactam antibiotics,^{1 44 45 46 47 48 151 157 173 222 241 243 248 256 264 267 274 275 289} hypersensitivity reactions to aztreonam have occurred rarely when the drug was used in patients with a history of hypersensitivity to penicillins and/or cephalosporins.^{1 173 192 290 296}

Prior to initiation of therapy, make careful inquiry concerning previous hypersensitivity reactions to β-lactam antibiotics or any allergens.¹ Use with caution in patients hypersensitive to β-lactam antibiotics (e.g., penicillins, cephalosporins, cephamycins).¹

General Precautions

Selection and Use of Anti-infectives

To reduce development of drug-resistant bacteria and maintain effectiveness of aztreonam and other antibacterials, use only for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.^a

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

Because aztreonam has little or no activity against gram-positive bacteria and anaerobes, concomitant use of another anti-infective may be indicated when the drug is used empirically in infections that may involve such bacteria (e.g., gynecologic, intra-abdominal, respiratory tract).^{171 173 183 211 213 214}

Specific Populations

Pregnancy

Category B.¹

Lactation

Low concentrations distributed into milk.¹ Consider temporarily discontinuing breast-feeding during aztreonam therapy.¹

Pediatric Use

Safety and efficacy not established in children <9 months of age.¹

Use in children 9 months to 16 years of age supported by evidence from adequate and well-controlled studies in adults with additional efficacy, safety, and pharmacokinetic data from noncomparative clinical studies in pediatric patients.¹ Adverse effects reported in pediatric patients similar to those reported in adults.¹

Data in pediatric patients insufficient regarding treatment of septicemia or skin and skin structure infections (where the skin infection is believed or known to be caused by H. influenzae type b).¹

Higher dosage may be warranted in pediatric patients with cystic fibrosis.¹

Geriatric Use

Insufficient experience in patients ≥65 years of age to determine whether geriatric patients respond differently than younger adults.^a

Select dosage with caution because of the greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease and drug therapy observed in the elderly.^a

Serum half-life of aztreonam slightly longer in geriatric adults than in younger adults.³ Substantially eliminated by kidneys; risk of toxicity may be greater in patients with impaired renal function.^a Since geriatric patients are more likely to have renal impairment, monitor renal function and adjust dosage if needed.^a

Hepatic Impairment

Monitor hepatic function.¹

Renal Impairment

Monitor renal function.¹

Common Adverse Effects

Local reactions at injection site (e.g., phlebitis/thrombophlebitis following IV administration or discomfort/swelling following IM administration); GI effects (diarrhea, nausea, vomiting); hypersensitivity (rash).¹

Interactions for Aztreonam

Specific Drugs and Laboratory Tests

Drug or Test	Interaction	Comments
Aminoglycosides	In vitro evidence of additive or synergistic antibacterial effects against Ps. aeruginosa1 38 48 57 78 88 107 111 112 128 131 140 and some strains of Ps. cepacia,48 107 131 Ps. fluorescens,131 or Ps. maltophilia131 In vitro evidence of synergistic antibacterial effects against Enterobacteriaceae (e.g., Enterobacter, E. coli, Klebsiella, Serratia)1 57 78 88 140 In vitro synergism reported occasionally against Acinetobacter, but usually only additive or indifferent131 264 Indifference reported against gram-positive bacteria (e.g., S. aureus, S. epidermidis, E. faecalis)88 92 131	Because of potential nephrotoxicity and ototoxicity, monitor renal function (especially if high aminoglycoside dosage is used or if therapy is prolonged)1
Chloramphenicol	In vitro studies using K. pneumoniae indicate that chloramphenicol can antagonize the bactericidal activity of aztreonam139	It has been suggested that chloramphenicol should be administered a few hours after aztreonam; the necessity of this precaution has not been established139
Clavulanic acid	In vitro evidence of synergistic effects against some β-lactamase-producing Enterobacter, Klebsiella, or B. fragilis;48 88 antagonism also may occur127 276 Concomitant use does not alter in vitro susceptibility of S. aureus to aztreonam since resistance to the drug in these organisms is intrinsic234
Clindamycin	In vitro evidence of synergistic effects against some strains of E. coli, Klebsiella, or Enterobacter, although the combination more frequently is indifferent or additive against these organisms77 Indifference or slightly additive effects reported against anaerobic bacteria38 264 Total urinary excretion of aztreonam may be increased, but other pharmacokinetic parameters not affected154	Not considered clinically important154
Furosemide	Possible increased serum aztreonam concentrations1	Not considered clinically important1
β-lactam antibiotics	In vitro evidence of additive or synergistic antibacterial effects with some β-lactams (piperacillin, cefotaxime) against some strains of Ps. aeruginosa;78 antagonism against Ps. aeruginosa reported with imipenem92 When used with some β-lactams (ampicillin, piperacillin, cefotaxime), indifference or only slightly additive effects occur against Enterobacteriaceae, including Enterobacter, E. coli, S. marcescens, or Klebsiella77 78 92 When used with cefoxitin, in vitro evidence of synergism against some strains of Enterobacter, E. coli, Klebsiella, S. marcescens, Salmonella, or Shigella;77 antagonism also reported against some Enterobacter or S. marcescens77 127	Because of the potential for antagonism, β-lactams that are potent inducers of β-lactamase production (e.g., cefoxitin, imipenem) should not be used concomitantly with aztreonam1 264
Metronidazole	Indifferent or slightly additive effects reported against anaerobic bacteria38 264 Possible decrease in peak serum concentrations of aztreonam; other pharmacokinetic parameters not affected154	Not considered clinically important154
Probenecid	Decreased rate of renal tubular secretion of aztreonam and decreased binding of aztreonam to plasma proteins1 2 34 56	Not sufficient to be of therapeutic benefit1 2 34 56
Tests for glucose	Possible false-positive reactions in urine glucose tests using Clinitest, Benedict’s solution, or Fehling’s solution240	Use glucose tests based on enzymatic glucose oxidase reactions (e.g., Clinistix, Tes-Tape)240

Aztreonam Pharmacokinetics

Absorption

Bioavailability

Poorly absorbed from GI tract; bioavailability is <1% following oral administration.^{2 8 46 47 48 56 193}

Rapidly and completely absorbed following IM administration;^{2 6 7 29 46 47 48 56 256} peak serum concentrations generally attained within 1 hour after an IM dose.^{1 2 6 7 29 46}

Although peak serum concentrations attained with an IM dose are slightly lower than those attained with an equivalent IV dose, serum aztreonam concentrations ≥1 hour after dosing are similar.^{1 2 264}

Special Populations

Pharmacokinetics in pediatric patients ≥9 months of age are similar to those in adults.¹

Distribution

Extent

Widely distributed into body tissues and fluids following IM or IV administration.^{21 46 48 264} Distributed into skeletal muscle,^{1 21 25 264 266} adipose tissue,^{1 21 264 266} skin,^{1 21 264} bone,^{1 20 25 264} gallbladder,^{1 21 264} liver,^{1 21 264} lungs,^{1 25 208 264} kidneys,^{1 2 22 264 266} atrial appendage,^{1 25 264} intestines,^{1 21 264} prostatic tissue,^{1 24 48 56 264} myometrium,^{264 266} endometrium,^{1 25 264 266} fallopian tubes,^{1 264 266} ovaries,^{1 264} and cervical and vaginal tissue.²⁶⁶ Also distributed into saliva,^{1 2}