Augmentin XR

Medical Reviewer: John P. Cunha, DO, FACOEP Last updated on RxList: 11/15/2022

Drug Summary

What Is Augmentin XR?

Augmentin XR (amoxicillin/clavulante potassium) Extended Release Tablets is a combination of an antibiotic and a B-lactamase inhibitor indicated for patients with community-acquired pneumonia or acute bacterial sinusitis. Augmentin XR is available in generic form.

What Are Side Effects of Augmentin XR?

Augmentin XR may cause serious side effects including:

  • severe stomach pain,
  • diarrhea that is watery or bloody,
  • pale or yellowed skin,
  • dark-colored urine,
  • fever,
  • confusion,
  • weakness,
  • loss of appetite,
  • upper stomach pain,
  • yellowing of the skin or eyes (jaundice),
  • easy bruising or bleeding,
  • little or no urination,
  • sore throat,
  • swelling in your face or tongue,
  • burning in your eyes, and
  • skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling

Get medical help right away, if you have any of the symptoms listed above.

Side effects of Augmentin XR include:

  • diarrhea,
  • gas,
  • stomach pain,
  • nausea,
  • vomiting,
  • headache,
  • skin rash or itching,
  • white patches in your mouth or throat, or
  • vaginal yeast infection (itching or discharge).

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheadedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Augmentin XR

The recommended dose of Augmentin XR to treat bacterial sinusitis is 2 tablets every 12 hours, for a duration of 10 days. The recommended dose of Augmentin XR to treat pneumonia is 2 tablets every 12 hours, for 7 to 10 days.

What Drugs, Substances, or Supplements Interact with Augmentin XR?

Augmentin XR may interact with allopurinol, probenecid, blood thinners, or other antibiotics. Tell your doctor all medications and supplements you use.

Augmentin XR During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant during treatment with Augmentin XR; it is not expected to be harmful to a fetus. Augmentin XR can make birth control pills less effective. Talk to your doctor about using a non-hormone method of birth control. Augmentin XR can pass into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding.

Additional Information

Our Augmentin XR (amoxicillin/clavulante potassium) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

Drug Description


AUGMENTIN XR (amoxicillin and clavulanate potassium) extended release tablet for oral use is an antibacterial combination consisting of the semisynthetic antibacterial amoxicillin (present as amoxicillin trihydrate and amoxicillin sodium) and the β-lactamase inhibitor clavulanate potassium (the potassium salt of clavulanic acid). Amoxicillin is an analog of ampicillin, derived from the basic penicillin nucleus 6-aminopenicillanic acid. The amoxicillin trihydrate molecular formula is C16H19N3O5S•3H2O, and the molecular weight is 419.45. Chemically, amoxicillin trihydrate is (2S,5R,6R)-6-[(R)-(-)-2-Amino-2-(p-hydroxyphenyl)acetamido]-3,3dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid trihydrate and may be represented structurally as:

Amoxicillin sodium - Structural Formula Illustration

The amoxicillin sodium molecular formula is C16H18N3NaO5S, and the molecular weight is 387.39. Chemically, amoxicillin sodium is [2 -[2α,5α,6β(S*)]]-6-[[Amino(4hydroxyphenyl)acetyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2carboxylic acid monosodium salt and may be represented structurally as:

Amoxicillin sodium - Structural Formula Illustration

Clavulanic acid is produced by the fermentation of Streptomyces clavuligerus. It is a βlactam structurally related to the penicillins and possesses the ability to inactivate a wide variety of β-lactamases by blocking the active sites of these enzymes. Clavulanic acid is particularly active against the clinically important plasmid-mediated β-lactamases frequently responsible for transferred drug resistance to penicillins and cephalosporins. The clavulanate potassium molecular formula is C8H8KNO5, and the molecular weight is 237.25. Chemically, clavulanate potassium is potassium (Z)-(2R,5R)-3-(2-hydroxy ethylidene)-7-oxo-4-oxa-1-azabicyclo[3.2.0]-heptane-2-carboxylate, and may be represented structurally as:

Clavulanate potassium - Structural Formula Illustration

Inactive Ingredients

Citric acid, colloidal silicon dioxide, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, sodium starch glycolate, titanium dioxide, and xanthan gum.

Each tablet of AUGMENTIN XR contains approximately 13 mg of potassium and 30 mg of sodium.



To reduce the development of drug-resistant bacteria and maintain the effectiveness of AUGMENTIN XR and other antibacterial drugs, AUGMENTIN XR should be used only to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

AUGMENTIN XR Extended Release Tablets are indicated for the treatment of patients with community-acquired pneumonia or acute bacterial sinusitis due to confirmed, or suspected β-lactamase–producing pathogens (i.e., H. influenzae, M. catarrhalis, H. parainfluenzae, K. pneumoniae, or methicillin-susceptible S. aureus) and S. pneumoniae with reduced susceptibility to penicillin (i.e., penicillin MICs = 2 mcg/mL). AUGMENTIN XR is not indicated for the treatment of infections due to S. pneumoniae with penicillin MICs ≥ 4 mcg/mL. Data are limited with regard to infections due to S. pneumoniae with penicillin MICs ≥ 4 mcg/ml [see Clinical Studies].

In patients with community-acquired pneumonia in whom penicillin-resistant S. pneumoniae is suspected, bacteriological studies should be performed to determine the causative organisms and their susceptibility when AUGMENTIN XR is prescribed.

Acute bacterial sinusitis or community-acquired pneumonia due to a penicillin-susceptible strain of S. pneumoniae plus a β-lactamase–producing pathogen can be treated with another AUGMENTIN® (amoxicillin/clavulanate potassium) product containing lower daily doses of amoxicillin (i.e., 500 mg every 8 hours or 875 mg every 12 hours). Acute bacterial sinusitis or community-acquired pneumonia due to S. pneumoniae alone can be treated with amoxicillin.



AUGMENTIN XR should be taken at the start of a meal to enhance the absorption of amoxicillin and to minimize the potential for gastrointestinal intolerance. AUGMENTIN XR is not recommended to be taken with a high-fat meal, because clavulanate absorption is decreased. [see CLINICAL PHARMACOLOGY].


The recommended dose of AUGMENTIN XR is 4,000 mg/250 mg daily according to the following table:

Indication Dose Duration
Acute bacterial sinusitis 2 tablets q12h 10 days
Community-acquired pneumonia 2 tablets q12h 7-10 days

Tablets of AUGMENTIN (250 mg or 500 mg) CANNOT be used to provide the same dosages as AUGMENTIN XR Extended Release Tablets. This is because AUGMENTIN XR contains 62.5 mg of clavulanic acid, while the AUGMENTIN 250-mg and 500-mg tablets each contain 125 mg of clavulanic acid. In addition, the Extended Release Tablet provides an extended time course of plasma amoxicillin concentrations compared to immediate-release Tablets. Thus, two AUGMENTIN 500-mg tablets are not equivalent to one AUGMENTIN XR tablet.

Scored AUGMENTIN XR Extended Release Tablets are available for adult patients who have difficulty swallowing. The scored tablet is not intended to reduce the dosage of medication taken; as stated in the table above, the recommended dose of AUGMENTIN XR is two tablets twice a day (every 12 hours).

Renally Impaired Patients

The pharmacokinetics of AUGMENTIN XR have not been studied in patients with renal impairment. AUGMENTIN XR is contraindicated in patients with a creatinine clearance of < 30 mL/min and in hemodialysis patients [see CONTRAINDICATIONS].

Hepatically Impaired Patients

Hepatically impaired patients should be dosed with caution and hepatic function monitored at regular intervals [see WARNINGS AND PRECAUTIONS].

Pediatric Use

Pediatric patients who weigh 40 kg or more and can swallow tablets should receive the adult dose [see Use in Specific Populations].

Geriatric Use

No dosage adjustment is required for the elderly [see Use In Specific Populations].


Dosage Forms And Strengths

AUGMENTIN XR Extended Release Tablets

Each white, oval film-coated bilayer scored tablet, debossed with AUGMENTIN XR, contains amoxicillin trihydrate and amoxicillin sodium equivalent to a total of 1,000 mg of amoxicillin and clavulanate potassium equivalent to 62.5 mg of clavulanic acid.

Storage And Handling

AUGMENTIN XR Extended Release Tablets: Each white, oval film-coated bilayer scored tablet, debossed with AUGMENTIN XR, contains amoxicillin trihydrate and amoxicillin sodium equivalent to a total of 1,000 mg of amoxicillin and clavulanate potassium equivalent to 62.5 mg of clavulanic acid.

NDC 43598-020-28 Bottles of 28 (7 day XR pack)
NDC 43598-020-40 Bottles of 40 (10 day XR pack)


Dispense in original container.

Store tablets at or below 25°C (77°F).

Keep out of reach of children.

Manufactured by: Dr. Reddy's Laboratories Tennessee LLC, Bristol, TN 37620. Revised: April 2014

Side Effects


The following are discussed in more detail in other sections of the labeling:

  • Anaphylactic reactions [see WARNINGS AND PRECAUTIONS]
  • Severe Cutaneous Adverse Reactions [see WARNINGS AND PRECAUTIONS]
  • Hepatic Dysfunction [see WARNINGS AND PRECAUTIONS]
  • Clostridioides difficile-associated diarrhea (CDAD) [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

In clinical trials, 5,643 patients have been treated with AUGMENTIN XR. The most frequently reported adverse reactions which were suspected or probably drug-related were diarrhea (15%), vaginal mycosis (3%), nausea (2%), and loose stools (2%). AUGMENTIN XR had a higher rate of diarrhea which required corrective therapy (4% versus 3% for AUGMENTIN XR and all comparators, respectively). Two percent of patients discontinued therapy because of drug-related adverse reactions.

Postmarketing Experience

In addition to adverse reactions reported from clinical trials, the following have been identified during postmarketing use of AUGMENTIN products, including AUGMENTIN XR. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to a combination of their seriousness, frequency of reporting, or potential causal connection to AUGMENTIN.


Diarrhea, nausea, vomiting, indigestion, gastritis, stomatitis, glossitis, black “hairy” tongue, mucocutaneous candidiasis, enterocolitis, and hemorrhagic/ pseudomembranous colitis. Onset of pseudomembranous colitis symptoms may occur during or after antibacterial treatment [see WARNINGS AND PRECAUTIONS].


Hypersensitivity reactions, anaphylactic/anaphylactoid reactions (including shock), angioedema, serum sickness-like reactions (urticaria or skin rash accompanied by arthritis, arthralgia, myalgia, and frequently fever), hypersensitivity vasculitis [see WARNINGS AND PRECAUTIONS].

Skin And Appendages

Rashes, pruritus, urticaria, erythema multiforme, SJS, TEN, DRESS, AGEP, exfoliative dermatitis [see WARNINGS AND PRECAUTIONS].


A moderate rise in AST (SGOT) and/or ALT (SGPT) has been noted in patients treated with ampicillin-class antibacterials, but the significance of these findings is unknown. Hepatic dysfunction, including hepatitis and cholestatic jaundice, [see CONTRAINDICATIONS], increases in serum transaminases (AST and/or ALT), serum bilirubin, and/or alkaline phosphatase, has been reported with AUGMENTIN or AUGMENTIN XR. It has been reported more commonly in the elderly, in males, or in patients on prolonged treatment. The histologic findings on liver biopsy have consisted of predominantly cholestatic, hepatocellular, or mixed cholestatichepatocellular changes.

The onset of signs/symptoms of hepatic dysfunction may occur during or several weeks after therapy has been discontinued. The hepatic dysfunction, which may be severe, is usually reversible. Deaths have been reported [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS].


Interstitial nephritis, hematuria, and crystalluria have been reported [see OVERDOSE].

Hemic And Lymphatic Systems

Anemia, including hemolytic anemia, thrombocytopenia, thrombocytopenic purpura, eosinophilia, leukopenia, and agranulocytosis have been reported during therapy with penicillins. These reactions are usually reversible on discontinuation of therapy and are believed to be hypersensitivity phenomena. There have been reports of increased prothrombin time in patients receiving AUGMENTIN and anticoagulant therapy concomitantly.

Central Nervous System

Agitation, anxiety, behavioral changes, aseptic meningitis, confusion, convulsions, dizziness, headache, insomnia, and reversible hyperactivity have been reported.


Tooth discoloration (brown, yellow, or gray staining) has been reported. Most reports occurred in pediatric patients. Discoloration was reduced or eliminated with brushing or dental cleaning in most cases.

Drug Interactions



Probenecid decreases the renal tubular secretion of amoxicillin. Concurrent use with AUGMENTIN XR may result in increased and prolonged blood levels of amoxicillin. Co-administration of probenecid is not recommended.

Oral Anticoagulants

Abnormal prolongation of prothrombin time (increased international normalized ratio [INR]) has been reported in patients receiving amoxicillin and oral anticoagulants. Appropriate monitoring should be undertaken when anticoagulants are prescribed concurrently. Adjustments in the dose of oral anticoagulants may be necessary to maintain the desired level of anticoagulation.


The concurrent administration of allopurinol and amoxicillin substantially increases the incidence of rashes in patients receiving both drugs as compared to patients receiving amoxicillin alone. It is not known whether this potentiation of amoxicillin rashes is due to allopurinol or the hyperuricemia present in these patients. In controlled clinical trials of AUGMENTIN XR, 25 patients received concomitant allopurinol and AUGMENTIN XR. No rashes were reported in these patients. However, this sample size is too small to allow for any conclusions to be drawn regarding the risk of rashes with concomitant AUGMENTIN XR and allopurinol use.

Oral Contraceptives

AUGMENTIN XR may affect intestinal flora, leading to lower estrogen reabsorption and reduced efficacy of combined oral estrogen/progesterone contraceptives.

Effects On Laboratory Tests

High urine concentrations of amoxicillin may result in false-positive reactions when testing for the presence of glucose in urine using CLINITEST®, Benedict’s Solution, or Fehling’s Solution. Since this effect may also occur with AUGMENTIN XR, it is recommended that glucose tests based on enzymatic glucose oxidase reactions be used.

Following administration of amoxicillin to pregnant women, a transient decrease in plasma concentration of total conjugated estriol, estriol-glucuronide, conjugated estrone, and estradiol has been noted.

Warnings & Precautions


Included as part of the "PRECAUTIONS" Section


Serious Allergic Reactions, Including Anaphylaxis

Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving AUGMENTIN XR. These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. Before initiating therapy with AUGMENTIN XR, careful inquiry should be made regarding previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens. If an allergic reaction occurs, discontinue AUGMENTIN XR and institute appropriate therapy.

Severe Cutaneous Adverse Reactions

AUGMENTIN XR may cause severe cutaneous adverse reactions (SCAR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP). If patients develop a skin rash, they should be monitored closely, and AUGMENTIN XR discontinued if lesions progress.

Hepatic Dysfunction

Use AUGMENTIN XR with caution in patients with evidence of hepatic dysfunction. Hepatic toxicity associated with the use of Augmentin XR is usually reversible. Deaths have been reported (fewer than one death reported per estimated four million prescriptions worldwide). These have generally been cases associated with serious underlying diseases or concomitant medications [see CONTRAINDICATIONS, and ADVERSE REACTIONS].

Clostridioides Difficile-Associated Diarrhea (CDAD)

Clostridioides difficile-associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including AUGMENTIN XR, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxinproducing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial drug use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, ongoing antibacterial drug use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile, and surgical evaluation instituted as clinically indicated. should be instituted as clinically indicated.

Skin Rash In Patients With Mononucleosis

A high percentage of patients with mononucleosis who receive amoxicillin develop an erythematous skin rash. Thus, AUGMENTIN XR should not be administered to patients with mononucleosis.

Potential For Microbial Overgrowth

The possibility of superinfections with mycotic or bacterial pathogens should be kept in mind during therapy. If superinfections occur (usually involving Pseudomonas spp. or Candida spp.), the drug should be discontinued and/or appropriate therapy instituted.

Development Of Drug-Resistant Bacteria

Prescribing AUGMENTIN XR in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Long-term studies in animals have not been performed to evaluate carcinogenic potential. The mutagenic potential of AUGMENTIN was investigated in vitro with an Ames test, a human lymphocyte cytogenetic assay, a yeast test, and a mouse lymphoma forward mutation assay, and in vivo with mouse micronucleus tests and a dominant lethal test. All were negative apart from the in vitro mouse lymphoma assay, where weak activity was found at very high, cytotoxic concentrations. AUGMENTIN at oral doses of up to 1,200 mg/kg/day (1.9 times the maximum human dose of amoxicillin and 15 times the maximum human dose of clavulanate based on body surface area) was found to have no effect on fertility and reproductive performance in rats dosed with a 2:1 ratio formulation of amoxicillin: clavulanate.

Use In Specific Populations


Teratogenic Effects

Pregnancy Category B

Reproduction studies performed in pregnant rats and mice given AUGMENTIN at oral doses up to 1,200 mg/kg/day revealed no evidence of harm to the fetus due to AUGMENTIN. In terms of body surface area, the doses in rats were 1.6 times the maximum human oral dose of amoxicillin and 13 times the maximum human dose for clavulanate. For mice, these doses were 0.9 and 7.4 times the maximum human oral dose of amoxicillin and clavulanate, respectively. There are, however, no adequate and well controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Labor And Delivery

Oral ampicillin is poorly absorbed during labor. Studies in guinea pigs have shown that intravenous administration of ampicillin decreased the uterine tone, frequency of contractions, height of contractions, and duration of contractions. However, it is not known whether the use of AUGMENTIN XR in humans during labor or delivery has immediate or delayed adverse effects on the fetus, prolongs the duration of labor, or increases the likelihood that forceps delivery or other obstetrical intervention or resuscitation of the newborn will be necessary. In a single study in women with premature rupture of fetal membranes, it was reported that prophylactic treatment with AUGMENTIN may be associated with an increased risk of necrotizing enterocolitis in neonates.

Nursing Mothers

Amoxicillin has been shown to be excreted in human milk; therefore, caution should be exercised when AUGMENTIN XR is administered to a nursing woman.

Pediatric Use

The safety and effectiveness of AUGMENTIN XR have been established for pediatric patients weighing greater than or equal to 40 kg who are able to swallow tablets. Use of AUGMENTIN XR in these pediatric patients is supported by evidence from adequate and well-controlled trials of adults with acute bacterial sinusitis and community-acquired pneumonia with additional data from a pediatric pharmacokinetic study.

A pharmacokinetic study in pediatric patients (7 to 15 years of age and weighing greater than or equal to 40 kg) was conducted [see CLINICAL PHARMACOLOGY].

The adverse event profile in 44 pediatric patients who received at least one dose of AUGMENTIN XR was consistent with the established adverse event profile for the product in adults.

Geriatric Use

Of the total number of subjects in clinical studies of AUGMENTIN XR, 18% were 65 years or older and 7% were 75 years or older. No overall differences in safety and effectiveness were observed between these subjects and younger subjects, and other clinical experience has not reported differences in responses between the elderly and younger patients, but a greater sensitivity of some older individuals cannot be ruled out.

This drug is known to be substantially excreted by the kidney, and the risk of dose dependent toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, it may be useful to monitor renal function.

Renal Impairment

The pharmacokinetics of AUGMENTIN XR have not been studied in patients with renal impairment. AUGMENTIN XR is contraindicated in patients with a creatinine clearance of less than 30 mL/min and in hemodialysis patients [see CONTRAINDICATIONS].

Hepatic Impairment

Hepatically impaired patients should be dosed with caution and hepatic function monitored at regular intervals [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS].



Following overdosage, patients have experienced primarily gastrointestinal symptoms including stomach and abdominal pain, vomiting, and diarrhea. Rash, hyperactivity, or drowsiness have also been observed in a small number of patients.

In the case of overdosage, discontinue AUGMENTIN XR, treat symptomatically, and institute supportive measures as required. If the overdosage is very recent and there is no contraindication, an attempt at emesis or other means of removal of drug from the stomach may be performed. A prospective study of 51 pediatric patients at a poison control center suggested that overdosages of less than 250 mg/kg of amoxicillin are not associated with significant clinical symptoms and do not require gastric emptying1.

Interstitial nephritis resulting in oliguric renal failure has been reported in a small number of patients after overdosage with amoxicillin.

Crystalluria, in some cases leading to renal failure, has also been reported after amoxicillin overdosage in adult and pediatric patients. In the case of overdosage, adequate fluid intake and diuresis should be maintained to reduce the risk of amoxicillin crystalluria.

Renal impairment appears to be reversible with cessation of drug administration. High blood levels may occur more readily in patients with impaired renal function because of decreased renal clearance of both amoxicillin and clavulanate. Both amoxicillin and clavulanate are removed from the circulation by hemodialysis.



Serious Hypersensitivity Reactions

AUGMENTIN XR is contraindicated in patients with a history of serious hypersensitivity reactions (e.g., anaphylaxis or Stevens-Johnson syndrome) to amoxicillin, clavulanate or to other beta-lactam antibacterial drugs (e.g., penicillins and cephalosporins).

Cholestatic Jaundice/Hepatic Dysfunction

AUGMENTIN XR is contraindicated in patients with a previous history of cholestatic jaundice/hepatic dysfunction associated with treatment with amoxicillin/clavulanate potassium.

Renal Impairment

AUGMENTIN XR is contraindicated in patients with severe renal impairment (creatinine clearance less than 30 mL/min) and in hemodialysis patients.


1. Swanson-Biearman B, Dean BS, Lopez G, Krenzelok EP. The effects of penicillin and cephalosporin ingestions in children less than six years of age. Vet Hum Toxicol. 1988; 30:66-67.

Clinical Pharmacology


Mechanism Of Action

AUGMENTIN XR is an antibacterial drug [see Microbiology].


AUGMENTIN XR is an extended-release formulation which provides sustained plasma concentrations of amoxicillin. Amoxicillin systemic exposure achieved with AUGMENTIN XR is similar to that produced by the oral administration of equivalent doses of amoxicillin alone.


Amoxicillin and clavulanate potassium are well absorbed from the gastrointestinal tract after oral administration of AUGMENTIN XR.

In a study of healthy adult volunteers, the pharmacokinetics of AUGMENTIN XR were compared when administered in a fasted state, at the start of a standardized meal (612 kcal, 89.3 g carb, 24.9 g fat, and 14 g protein), or 30 minutes after a high-fat meal.

When the systemic exposure to both amoxicillin and clavulanate is taken into consideration, AUGMENTIN XR is optimally administered at the start of a standardized meal. Absorption of amoxicillin is decreased in the fasted state. AUGMENTIN XR is not recommended to be taken with a high-fat meal, because clavulanate absorption is decreased. The pharmacokinetics of the components of AUGMENTIN XR following administration of two AUGMENTIN XR tablets at the start of a standardized meal are presented in Table 2.

Table 2: Mean (SD) Pharmacokinetic Parameter for Amoxicillin and Clavulanate Following Oral Administration of Two AUGMENTIN XR Tablets (2,000 mg/125 mg) to Healthy Adult Volunteers (n equals 55) Fed a Standardized Meal

Parameter (units) Amoxicillin Clavulanate
AUC(0-inf) (mcg•hr/mL) 71.6 (16.5) 5.29 (1.55)
Cmax (mcg/mL) 17.0 (4.0) 2.05 (0.80)
Tmax (hours)a 1.50 (1.00 to 6.00) 1.03 (0.75 to 3.00)
T1/2 (hours) 1.27 (0.20) 1.03 (0.17)
a Median (range)

The half-life of amoxicillin after the oral administration of AUGMENTIN XR is approximately 1.3 hours, and that of clavulanate is approximately 1.0 hour.


Neither component in AUGMENTIN XR is highly protein-bound; clavulanate has been found to be approximately 25% bound to human serum and amoxicillin approximately 18% bound.

Amoxicillin diffuses readily into most body tissues and fluids, with the exception of the brain and spinal fluid. The results of experiments involving the administration of clavulanic acid to animals suggest that this compound, like amoxicillin, is well distributed in body tissues.


Clearance of amoxicillin is predominantly renal, with approximately 60% to 80% of the dose being excreted unchanged in urine, whereas clearance of clavulanate has both a renal (30% to 50%) and a non-renal component.

Drug Interactions

Concurrent administration of probenecid delays amoxicillin excretion but does not delay renal excretion of clavulanate [see DRUG INTERACTIONS].

In a study of adults, the pharmacokinetics of amoxicillin and clavulanate were not administration of an antacid (MAALOX®), either simultaneously with or 2 AUGMENTIN XR.


In a study of pediatric patients with acute bacterial sinusitis, 7 to 15 years of age, and weighing at least 40 kg, the pharmacokinetics of amoxicillin and clavulanate were assessed following administration of AUGMENTIN XR 2,000 mg/125 mg (as two 1,000 mg/62.5 mg tablets) every 12 hours with food (Table 3).

Table 3: Mean (SD) Pharmacokinetic Parameters for Amoxicillin and Clavulanate Following Oral Administration of Two AUGMENTIN XR Tablets (2,000 mg/125 mg) Every 12 Hours with Food to Pediatric Patients (7 to 15 Years of Age and Weighing greater than or equal to 40 kg) With Acute Bacterial Sinusitis

Parameter (units) Amoxicillin
(n equals 24)
(n equals 23)
AUC(0-τ) (mcg•hr/mL) 57.8 (15.6) 3.18 (1.37)
Cmax (mcg/mL) 11.0 (3.34) 1.17 (0.67)
Tmax (hours)a 2.0 (1.0 to 5.0) 2.0 (1.0 to 4.0)
T1/2(hours) 3.32 (2.21)b 0.94 (0.13)c
a Median (range).
b n equals 18.
c n equals 17.


Mechanism Of Action

Amoxicillin binds to penicillin-binding proteins within the bacterial cell wall and inhibits bacterial cell wall synthesis.

Clavulanic acid is a β-lactam, structurally related to penicillin, that may inactivate certain β-lactamase enzymes.


Resistance to penicillins may be mediated by destruction of the beta-lactam ring by a betalactamase, altered affinity of penicillin for target, or decreased penetration of the antibacterial drug to reach the target site. Amoxicillin alone is susceptible to degradation by β-lactamases, and therefore its spectrum of activity does not include bacteria that produce these enzymes.

Antimicrobial Activity

Amoxicillin/clavulanic acid has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections [see INDICATIONS].

Gram-positive Bacteria:

Staphylococcus aureus (methicillin-susceptible)
Streptococcus pneumoniae

Gram-negative Bacteria:

Haemophilus influenzae
Haemophilus parainfluenzae
Klebsiella pneumoniae
Moraxella catarrhalis

The following in vitro data are available, but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for amoxicillin and clavulanic acid against isolates of similar genus or organism group. However, the efficacy of amoxicillin and clavulanic acid in treating clinical infections caused by these bacteria have not been established in adequate and well-controlled clinical trials.

Gram-positive Bacteria:

Streptococcus pyogenes

Susceptibility Testing

For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see:

Clinical Studies

Acute Bacterial Sinusitis

Adults with a diagnosis of acute bacterial sinusitis (ABS) were evaluated in 3 clinical studies. In one study, 363 patients were randomized to receive either AUGMENTIN XR 2,000 mg/125 mg orally every 12 hours or levofloxacin 500 mg orally daily for 10 days in a double-blind, multicenter, prospective trial. These patients were clinically and radiologically evaluated at the test of cure (day 17 to 28) visit. The combined clinical and radiological responses were 84% for AUGMENTIN XR and 84% for levofloxacin at the test of cure visit in clinically evaluable patients (95% CI for the treatment difference equals -9.4, 8.3). The clinical response rates at the test of cure were 87% and 89%, respectively.

The other 2 trials were non-comparative, multicenter studies designed to assess the bacteriological and clinical efficacy of AUGMENTIN XR (2,000 mg/125 mg orally every 12 hours for 10 days) in the treatment of 2,288 patients with ABS. Evaluation timepoints were the same as in the prior study. Patients underwent maxillary sinus puncture for culture prior to receiving study medication. Patients with acute bacterial sinusitis due to S. pneumoniae with reduced susceptibility to penicillin were accrued through enrollment in these 2 open-label non-comparative clinical trials. Microbiologic eradication rates for key pathogens in these studies are shown in Table 4.

Table 4: Clinical Outcome for ABS

Penicillin MICs of S. pneumoniae Isolates Intent-To-Treat Clinically Evaluable
n/Na % 95% CIb n/Na % 95% CIb
All S. pneumoniae 344/370 93 - 318/326 98 -
MIC greater than or equal to 2.0 mcg/mLc 35/36 97 85.5, 99.9 30/31 96 83.3, 99.9
MIC equal to 2.0 mcg/mL 23/24 96 78.9, 99.9 19/20 95 75.1, 99.9
MIC greater than or equal to 4.0 mcg/mLd 12/12 100 73.5, 100 11/11 100 71.5, 100
H. influenzae 265/305 87 - 242/259 93 -
M. catarrhalis 94/105 90 - 86/90 96 -
a n/N equals patients with pathogen eradicated or presumed eradicated/total number of patients.
b Confidence limits calculated using exact probabilities.
c S. pneumoniae strains with penicillin MICs of greater than or equal to 2 mcg/mL are considered resistant to penicillin.
d Includes one patient each with S. pneumoniae penicillin MICs of 8 and 16 mcg/mL.

Community-Acquired Pneumonia

Four randomized, controlled, double-blind clinical studies and one non-comparative study were conducted in adults with community-acquired pneumonia (CAP). In comparative studies, 904 patients received AUGMENTIN XR at a dose of 2,000 mg/125 mg orally every 12 hours for 7 or 10 days. In the non-comparative study to assess both clinical and bacteriological efficacy, 1,122 patients received AUGMENTIN XR 2,000 mg/125 mg orally every 12 hours for 7 days. In the 4 comparative studies, the combined clinical success rate at test of cure ranged from 86% to 95% in clinically evaluable patients who received AUGMENTIN XR.

Data on the efficacy of AUGMENTIN XR in the treatment of community-acquired pneumonia due to S. pneumoniae with reduced susceptibility to penicillin were accrued from the 4 controlled clinical studies and the 1 non-comparative study. The majority of these cases were accrued from the non-comparative study. Results are shown in Table 5.

Table 5: Clinical Outcome for CAP due to S. pneumoniae

Penicillin MICs of S. pneumoniae Isolates Intent-To-Treat Clinically Evaluable
n/Na % 95% CIb n/Na % 95% CIb
All S. pneumoniae 318/367 87 - 275/297 93 -
MIC greater than or equal to 2.0 mcg/mLc 30/35 86 69.7, 95.2 24/25 96 79.6, 99.9
MIC equal to 2.0 mcg/mL 22/24 92 73.0, 99.0 18/18 100 81.5, 100
MIC greater than or equal to 4.0 mcg/mLd 8/11 73 39.0, 94.0 6/7 86 42.1, 99.6
a n/N equals patients with pathogen eradicated or presumed eradicated/total number of patients.
b Confidence limits calculated using exact probabilities.
c S. pneumoniae strains with penicillin MICs of greater than or equal to 2 mcg/mL are considered resistant to penicillin.
d Includes one patient each with S. pneumoniae penicillin MICs of 8 and 16 mcg/mL in the Intent-To-Treat group only.

Medication Guide


Administration Instructions

Counsel patients to take AUGMENTIN XR every 12 hours with a low fat meal or snack to reduce the possibility of gastrointestinal upset. If diarrhea develops and is severe or lasts more than 2 or 3 days, call your doctor.

Allergic Reactions

Counsel patients that AUGMENTIN XR contains a penicillin class drug product that can cause allergic reactions in some individuals.

Severe Cutaneous Adverse Reactions (SCAR)

Advise patients about the signs and symptoms of serious skin manifestations. Instruct patients to stop taking AUGMENTIN XR immediately and promptly report the first signs or symptoms of skin rash, mucosal lesions, or any other sign of hypersensitivity [see WARNINGS AND PRECAUTIONS].

Antibacterial Resistance

Patients should be counseled that antibacterial drugs, including AUGMENTIN XR, should only be used to treat bacterial infections. Antibacterial drugs do not treat viral infections (e.g., the common cold). When AUGMENTIN XR is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may: (1) decrease the effectiveness of the immediate treatment, and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by AUGMENTIN XR or other antibacterial drugs in the future.


Counsel patients that diarrhea is a common problem caused by antibacterials drugs which usually ends when the antibacterial drug is discontinued. Sometimes after starting treatment with antibacterial drugs, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as 2 or more months after having taken their last dose of the antibacterial drug. If diarrhea is severe or lasts more than 2 or 3 days, patients should contact their physician as soon as possible.

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.