Amoxicillin

EDICATION SAFETY ISSUES
Sound-alike/look-alike issues:
Amoxicillin may be confused with amoxapine, Amoxil®, Atarax®
Amoxil® may be confused with amoxapine, amoxicillin

International issues:
Fisamox® [Australia] may be confused with Fosamax® which is a brand name for alendronate in the U.S.
Fisamox® [Australia] may be confused with Vigamox® which is a brand name for moxifloxacin in the U.S.

U.S. BRAND NAMES — Amoxil®; Moxatag™

PHARMACOLOGIC CATEGORY
Antibiotic, Penicillin

DOSING: ADULTS
Usual dosage range: Oral: 250-500 mg every 8 hours or 500-875 mg twice daily or extended-release tablet 775 mg once daily

Anthrax exposure (CDC guidelines): Oral: Note: Postexposure prophylaxis in pregnant or nursing women only with documented susceptible organisms: 500 mg every 8 hours

Ear, nose, throat, genitourinary tract, or skin/skin structure infections:
Mild-to-moderate: Oral: 500 mg every 12 hours or 250 mg every 8 hours
Severe: Oral: 875 mg every 12 hours or 500 mg every 8 hours
Tonsillitis and/or pharyngitis: Oral: Extended release tablet: 775 mg once daily

Helicobacter pylorieradication: Oral: 1000 mg twice daily; requires combination therapy with at least one other antibiotic and an acid-suppressing agent (proton pump inhibitor or H2 blocker)

Lower respiratory tract infections: Oral: 875 mg every 12 hours or 500 mg every 8 hours

Lyme disease: Oral: 500 mg every 6-8 hours (depending on size of patient) for 21-30 days

Prophylaxis against infective endocarditis: Oral: 2 g 30-60 minutes before procedure. Note: American Heart Association (AHA) guidelines now recommend prophylaxis only in patients undergoing invasive procedures and in whom underlying cardiac conditions may predispose to a higher risk of adverse outcomes should infection occur. As of April 2007, routine prophylaxis for GI/GU procedures is no longer recommended by the AHA.

Prophylaxis in total joint replacement patients undergoing dental procedures which produce bacteremia: 2 g 1 hour prior to procedure

DOSING: PEDIATRIC

(For additional information see "Amoxicillin: Pediatric drug information")
Usual dosage range:
Children ≤ 3 months: Oral: 20-30 mg/kg/day divided every 12 hours
Children >3 months and <40 kg: Oral: 20-50 mg/kg/day in divided doses every 8-12 hours
Children ≥ 12 years: Oral: Extended-release tablet: 775 mg once daily

Acute otitis media: Children >3 months and <40 kg: Oral: 80-90 mg/kg/day divided every 12 hours

Anthrax exposure (CDC guidelines): Children >3 months and <40 kg: Oral: Note: Postexposure prophylaxis only with documented susceptible organisms: 80 mg/kg/day in divided doses every 8 hours (maximum: 500 mg/dose)

Community-acquired pneumonia:
4 months to <5 years: 80-100 mg/kg/day divided every 8 hours
5-15 years: 100 mg/kg/day divided every 8 hours; Note: Treatment with a macrolide or doxycycline (if age >8 years) is preferred due to higher prevalence of atypical pathogens in this age group

Ear, nose, throat, genitourinary tract, or skin/skin structure infections: Children >3 months and <40 kg: Oral:
Mild-to-moderate: 25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours
Severe: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours
Tonsillitis and/or pharyngitis: Children ≥ 12 years: Extended release tablet: 775 mg once daily

Lower respiratory tract infections: Children >3 months and <40 kg: Oral: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours

Lyme disease: Children >3 months and <40 kg: Oral: 25-50 mg/kg/day divided every 8 hours (maximum: 500 mg)

Prophylaxis against infective endocarditis: Children >3 months and <40 kg: Oral: 50 mg/kg 1 hour before procedure. Note: American Heart Association (AHA) guidelines now recommend prophylaxis only in patients undergoing invasive procedures and in whom underlying cardiac conditions may predispose to a higher risk of adverse outcomes should infection occur. As of April 2007, routine prophylaxis for GI/GU procedures is no longer recommended by the AHA.

DOSING: ELDERLY — Refer to adult dosing.

DOSING: RENAL IMPAIRMENT
Use of certain dosage forms (eg, extended-release 775 mg tablet and immediate-release 875 mg tablet) should be avoided in patients with Clcr <30 mL/minute or patients requiring hemodialysis
Clcr 10-30 mL/minute: 250-500 mg every 12 hours
Clcr <10 mL/minute: 250-500 mg every 24 hours

Moderately dialyzable (20% to 50%) by hemodialysis or peritoneal dialysis; approximately 50 mg of amoxicillin per liter of filtrate is removed by continuous arteriovenous or venovenous hemofiltration. Dose as per Clcr <10 mL/minute guidelines.

DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Capsule: 250 mg, 500 mg
Amoxil®: 500 mg [DSC]

Powder for suspension, oral: 125 mg/5 mL (80 mL, 100 mL, 150 mL); 200 mg/5 mL (50 mL, 75 mL, 100 mL); 250 mg/5 mL (80 mL, 100 mL, 150 mL); 400 mg/5 mL (50 mL, 75 mL, 100 mL)
Amoxil®: 250 mg/5 mL (100 mL, 150 mL) [contains sodium benzoate; bubble gum flavor] [DSC]; 400 mg/5 mL (100 mL) [contains sodium benzoate; bubble gum flavor] [DSC]

Powder for suspension, oral [drops]:
Amoxil®: 50 mg/mL (30 mL) [contains sodium benzoate; bubble gum flavor] [DSC]

Tablet: 500 mg, 875 mg

Tablet, chewable: 125 mg, 200 mg, 250 mg, 400 mg

Tablet, extended release:
Moxatag™ : 775 mg

DOSAGE FORMS: CONCISE
Capsule: 250 mg, 500 mg

Powder for suspension, oral: 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, 400 mg/5 mL

Tablet: 500 mg, 875 mg

Tablet, chewable: 125 mg, 200 mg, 250 mg, 400 mg

Tablet, extended release:
Moxatag™ : 775 mg

GENERIC EQUIVALENT AVAILABLE — Yes: Excludes drops and extended-release formulation

ADMINISTRATION — Administer around-the-clock to promote less variation in peak and trough serum levels. The appropriate amount of suspension may be mixed with formula, milk, fruit juice, water, ginger ale, or cold drinks; administer dose immediately after mixing.

Moxatag™ extended release tablet: Administer within 1 hour of finishing a meal.

Some penicillins (eg, carbenicillin, ticarcillin, and piperacillin) have been shown to inactivate aminoglycosides in vitro. This has been observed to a greater extent with tobramycin and gentamicin, while amikacin has shown greater stability against inactivation. Concurrent use of these agents may pose a risk of reduced antibacterial efficacy in vivo, particularly in the setting of profound renal impairment. However, definitive clinical evidence is lacking. If combination penicillin/aminoglycoside therapy is desired in a patient with renal dysfunction, separation of doses (if feasible), and routine monitoring of aminoglycoside levels, CBC, and clinical response should be considered.

USE — Treatment of otitis media, sinusitis, and infections caused by susceptible organisms involving the upper and lower respiratory tract, skin, and urinary tract; prophylaxis of infective endocarditis in patients undergoing surgical or dental procedures; as part of a multidrug regimen for H. pylori eradication

USE - UNLABELED / INVESTIGATIONAL — Postexposure prophylaxis for anthrax exposure with documented susceptible organisms

ADVERSE REACTIONS SIGNIFICANT — Frequency not defined.

Central nervous system: Agitation, anxiety, behavioral changes, confusion, dizziness, headache, hyperactivity (reversible), insomnia, seizure

Dermatologic: Acute exanthematous pustulosis, erythematous maculopapular rash, erythema multiforme, exfoliative dermatitis, hypersensitivity vasculitis, mucocutaneous candidiasis, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria

Gastrointestinal: Black hairy tongue, diarrhea, hemorrhagic colitis, nausea, pseudomembranous colitis, tooth discoloration (brown, yellow, or gray; rare), vomiting

Hematologic: Agranulocytosis, anemia, eosinophilia, hemolytic anemia, leukopenia,thrombocytopenia, thrombocytopenia purpura

Hepatic: Acute cytolytic hepatitis, ALT increased, AST increased, cholestatic jaundice, hepatic cholestasis

Renal: Crystalluria

Miscellaneous: Anaphylaxis, serum sickness-like reaction

CONTRAINDICATIONS — Hypersensitivity to amoxicillin, penicillin, other beta-lactams, or any component of the formulation

WARNINGS / PRECAUTIONS
Concerns related to adverse effects: Anaphylactoid/hypersensitivity reactions: Serious and occasionally severe or fatal hypersensitivity (anaphylactoid) reactions have been reported in patients on penicillin therapy, especially with a history of beta-lactam hypersensitivity, history of sensitivity to multiple allergens, or previous IgE-mediated reactions (eg, anaphylaxis, angioedema, urticaria). Use with caution in asthmatic patients. Superinfection: Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment.

Disease-related concerns: Infectious mononucleosis: A high percentage of patients with infectious mononucleosis have developed rash during therapy; ampicillin-class antibiotics not recommended in these patients. Renal impairment: Use with caution in patients with renal impairment; dosage adjustment recommended. In addition, use of certain dosage forms (eg, extended-release 775 mg tablet and immediate-release 875 mg tablet) should be avoided in patients with Clcr <30 mL/minute or patients requiring hemodialysis.

Dosage form specific issues: Phenylalanine: Chewable tablets contain phenylalanine.

DRUG INTERACTIONS
Allopurinol: May enhance the potential for allergic or hypersensitivity reactions to Amoxicillin. Risk C: Monitor therapy

Fusidic Acid: May diminish the therapeutic effect of Penicillins. Risk D: Consider therapy modification

Methotrexate: Penicillins may decrease the excretion of Methotrexate. Risk C: Monitor therapy

Mycophenolate: Penicillins may decrease serum concentrations of the active metabolite(s) of Mycophenolate. This effect appears to be the result of impaired enterohepatic recirculation. Risk C: Monitor therapy

Tetracycline Derivatives: May diminish the therapeutic effect of Penicillins. Risk D: Consider therapy modification

Typhoid Vaccine: Antibiotics may diminish the therapeutic effect of Typhoid Vaccine. Only the live attenuated Ty21a strain is affected. Risk D: Consider therapy modification

Uricosuric Agents: May decrease the excretion of Penicillins. Risk C: Monitor therapy

PREGNANCY RISK FACTOR — B (show table)

PREGNANCY IMPLICATIONS — Adverse events have not been observed in animal studies; therefore, amoxicillin is classified as pregnancy category B. There is no documented increased risk of adverse pregnancy outcome or teratogenic effects caused by amoxicillin. It is the drug of choice for the treatment of chlamydial infections in pregnancy and for anthrax prophylaxis when penicillin susceptibility is documented.

Due to pregnancy-induced physiologic changes, amoxicillin clearance is increased during pregnancy resulting in lower concentrations and smaller AUCs. Oral ampicillin-class antibiotics are poorly-absorbed during labor.

LACTATION — Enters breast milk/compatible

BREAST-FEEDING CONSIDERATIONS — Very small amounts of amoxicillin are excreted in breast milk. The manufacturer recommends that caution be exercised when administering amoxicillin to nursing women. The AAP considers amoxicillin to be "usually compatible with breastfeeding." Nondose-related effects could include modification of bowel flora and allergic sensitization of the infant.

DIETARY CONSIDERATIONS — May be taken with food. Amoxil® chewable contains phenylalanine 1.82 mg per 200 mg tablet, phenylalanine 3.64 mg per 400 mg tablet.

Moxatag™ : Take within 1 hour of finishing a meal.

PRICING — (data from drugstore.com)
Capsules (Amoxicillin)
250 mg (90): $17.99
500 mg (30): $13.99

Capsules (Amoxil)
500 mg (30): $15.99

Chewable (Amoxicillin)
125 mg (21): $11.99
250 mg (30): $13.99

Chewable (Amoxil)
400 mg (20): $13.99

Suspension (reconstituted) (Amoxicillin)
250 mg/5 mL (150): $14.00
400 mg/5 mL (100): $16.99

Suspension (reconstituted) (Amoxil)
50 mg/mL (30): $8.99
200 mg/5 mL (100): $11.99
250 mg/5 mL (100): $8.99
250 mg/5 mL (150): $8.99
400 mg/5 mL (50): $8.99
400 mg/5 mL (75): $9.99
400 mg/5 mL (100): $11.99

Suspension (reconstituted) (Trimox)
125 mg/5 mL (100): $11.99
250 mg/5 mL (80): $11.99

Tablet, 24-hour (Moxatag)
775 mg (30): $249.98

Tablets (Amoxicillin)
500 mg (100): $49.99
875 mg (30): $26.99

Tablets (Amoxil)
500 mg (21): $12.99
875 mg (21): $27.99

MONITORING PARAMETERS — With prolonged therapy, monitor renal, hepatic, and hematologic function periodically; assess patient at beginning and throughout therapy for infection; monitor for signs of anaphylaxis during first dose

CANADIAN BRAND NAMES — Apo-Amoxi®; Gen-Amoxicillin; Lin-Amox; Mylan-Amoxicillin; Novamoxin®; Nu-Amoxi; PHL-Amoxicillin; PMS-Amoxicillin

INTERNATIONAL BRAND NAMES — Acilina (PY); Acimox (MX); Adbiotin (CO); Alfamox (IT); Almodan (GB); Almorsan (AR); Alphamox (AU); Amagesen Solutab (DE); Amicil (MX); Amimox (SE); Amobay (MX); Amoclave (ES); Amoclen (CZ); Amodex (FR); Amoflux (BR); Amohexal (AU); Amolin (JP, TW); Amosine (ID); Amotaks (PL); Amox (AE, BH, CY, EG, IL, IQ, IR, IT, JO, KW, LB, LY, OM, QA, SA, SY, YE); Amoxa (HK); Amoxal (VE); Amoxapen (BB, BM, BS, BZ, GY, JM, NL, SG, SR, TT); Amoxcil (CL); Amoxcillin (TH); Amoxcin (TW); Amoxi (IL); Amoxi TO (TH); Amoxi-basan (DE); Amoxicap (PK); Amoxicilina (CO, EC); Amoxicilline (PL); Amoxiclin (PE); Amoxico (PH); Amoxidal (AR, UY); Amoxidin (AE, BB, BF, BH, BJ, BM, BS, BZ, CI, CY, EG, ET, GH, GM, GN, GY, IL, IQ, IR, JM, JO, KE, KW, LB, LR, LY, MA, ML, MR, MU, MW, NE, NG, NL, OM, QA, SA, SC, SD, SL, SN, SR, SY, TN, TT, TZ, UG, YE, ZA, ZM, ZW); Amoxifur (MX); Amoxihexal (DE); Amoxil (AE, AU, BB, BF, BH, BJ, BM, BR, BS, BZ, CI, CY, EG, ET, GB, GH, GM, GN, GR, GY, ID, IE, IL, IQ, IR, JM, JO, KE, KW, LB, LR, LY, MA, ML, MR, MU, MW, MX, NE, NG, NL, NZ, OM, PE, PL, QA, SA, SC, SD, SL, SN, SR, SY, TN, TT, TZ, UG, YE, ZA, ZM, ZW); Amoxil Duo (AU); Amoxillin (IL, IT); Amoxin (FI); Amoxinova (MX); Amoxipen (IT); Amoxipenil (CN); Amoxisol (MX); Amoxivan (IN); Amoxivet (MX); Amoxsan (ID); Amoxsan Forte (ID); Amoxy-diolan (DE); Amoxycillin (PL); Amoxypen (DE, PE); Apo-Amoxi (MY, PL); Aroxin (SG); Azillin (CH); Bacihexal (PH); Bactamox (VE); Bactox (EE); Bactox Ge (FR); Baymox (HN); Beamoxy (MY); Bimxan (MX); Biotamoxal (AR); Bristamox (EC, FR); Bufamoxy (ID); Cilamox (AU, PH); Clamoxyl (AT, AU, BB, BE, BM, BS, BZ, CH, FR, GY, JM, JP, NL, PE, PT, SR, TT); Dimopen (MX); Duomox (BG, HN, PL); Dymoxin (TH); Efpinex (JP); Ethimox (ID); Farconcil (AE, BH, CY, EG, IL, IQ, IR, JO, KW, LB, LY, OM, QA, SA, SY, YE); Fisamox (AU); Flemoxin (AE, BH, CY, EG, IL, IQ, IR, JO, KW, LB, LY, OM, QA, SA, SY, YE); Flubiotic (ES); Foxolin (KP); Fullcilina (AR); Gexcil (PH); Gimalxina (MX); Gomcillin (KP); Grinsul (AR); Grunamox (EC, PL); Hiconcil (BE, FR, ID, NL, PL); Hidramox (MX); Hipen (BF, BJ, CI, ET, GH, GM, GN, KE, LR, MA, ML, MR, MU, MW, NE, NG, SC, SD, SL, SN, TN, TZ, UG, ZA, ZM, ZW); Ibiamox (AE, AU, BH, CY, EG, IL, IQ, IR, JO, KW, LB, LY, OM, QA, SA, SY, TH, YE); Ikamoxil (ID); Imacillin (DK, NO, SE); Imadrax (DK); Imaxilin (CO); Isimoxin (IT); Izoltil (AE, BF, BH, BJ, CI, CY, EG, ET, GH, GM, GN, IL, IQ, IR, JO, KE, KW, LB, LR, LY, MA, ML, MR, MU, MW, NE, NG, OM, QA, SA, SC, SD, SL, SN, SY, TN, TZ, UG, YE, ZA, ZM, ZW); Jutamox (DE); Lamoxy (IN); Magnimox (PE); Manmox (TH); Maxamox (AU, NZ); Maxcil (ZA); Meixil (TH); Milamox-BIG (TH); Mopen (IT); Mox (IN); Moxacin (AU, NZ); Moxarin (AE, BH, CY, EG, IL, IQ, IR, JO, KW, LB, LY, OM, QA, SA, SY, YE); Moxilen (BF, BJ, CI, ET, GH, GM, GN, HK, KE, LR, MA, ML, MR, MU, MW, MY, NE, NG, SC, SD, SG, SL, SN, TN, TW, TZ, UG, ZA, ZM, ZW); Moxitab (TH); Moxtid (ID); Moxylin (EC); Moxypen (IL, ZA); Moxyvit (IL); Novabritine (BE); Novamox (PH, PL); Novax (ID); Novoxil (BR); Ospamox (AE, AT, BG, BH, CY, DE, EG, HK, ID, IL, IQ, IR, JO, KW, LB, LY, NZ, OM, PE, PL, PT, QA, SA, SY, UY, YE); Pamocil (IT); Pamoxicillin (TW); Pamoxin (KP); Pasetocin (JP); Penamox (MX, NZ, PE); Penbiosyn (PH); Piramox (AE, BF, BH, BJ, CI, CY, EG, ET, GH, GM, GN, IL, IQ, IR, JO, KE, KW, LB, LR, LY, MA, ML, MR, MU, MW, NE, NG, OM, QA, SA, SC, SD, SL, SN, SY, TN, TZ, UG, YE, ZA, ZM, ZW); Polymox (MX); Pondnoxcill (TH); Rancil (TH); Ranmoxy (AU, ZA); Ranoxyl (MY, TH); Robamox (ID); Sawacillin (JP); Sawamezin (JP); Servamox (TW); Setmoxil (HK); Shamoxil (AE, BH, CY, EG, IL, IQ, IR, JO, KW, LB, LY, OM, QA, SA, SY, YE); Sia-mox (TH); Simoxil (IT); Solciclina (MX); Solpenox (ID); Sterimox (PH); Supercillin (TW); Teramoxyl (PH); Trifamox (AR, PY); Trimox (TH); Vastamox (PH); Velamox (PE); Widecillin (ID); Winpen (BF, BJ, CI, ET, GH, GM, GN, KE, LR, MA, ML, MR, MU, MW, NE, NG, SC, SD, SL, SN, TN, TZ, UG, ZA, ZM, ZW); Xalyn-Or (MX); Xazexy (PH); Yusimox (ID); Zamoxil (MY); Zerrsox (PH); Zimox (IT)

MECHANISM OF ACTION — Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins (PBPs) which in turn inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls, thus inhibiting cell wall biosynthesis. Bacteria eventually lyse due to ongoing activity of cell wall autolytic enzymes (autolysins and murein hydrolases) while cell wall assembly is arrested.

PHARMACODYNAMICS / KINETICS
Absorption: Oral: Rapid and nearly complete; food does not interfere
Extended-release tablet: Rate of absorption is slower compared to immediate-release formulations; food decreases the rate but not extent of absorption

Distribution: Widely to most body fluids and bone; poor penetration into cells, eyes, and across normal meninges
Pleural fluids, lungs, and peritoneal fluid; high urine concentrations are attained; also into synovial fluid, liver, prostate, muscle, and gallbladder; penetrates into middle ear effusions, maxillary sinus secretions, tonsils, sputum, and bronchial secretions
CSF:blood level ratio: Normal meninges: <1%; Inflamed meninges: 8% to 90%

Protein binding: 17% to 20%

Metabolism: Partially hepatic

Half-life elimination:
Neonates, full-term: 3.7 hours
Infants and Children: 1-2 hours
Adults: Normal renal function: 0.7-1.4 hours
Clcr <10 mL/minute: 7-21 hours

Time to peak: Capsule: 2 hours; Extended-release tablet: 3.1 hours; Suspension: 1 hour

Excretion: Urine (60% as unchanged drug); lower in neonatesNote: Extended-release tablets: In healthy volunteers, serum drug concentrations were below 0.25 mcg/mL and undetectable at 16 hours following dosing.

PATIENT INFORMATION — Take entire course of medication. Report diarrhea promptly. females should report symptoms of vaginitis. Pediatric drops may be placed on child's tongue or added to formula, milk, etc.

(For additional information see "Amoxicillin: Patient drug information")

PRODUCT AVAILABILITY
Moxatag™ : FDA approved January 2009; availability anticipated in March 2009

Moxatag™ is an extended-release tablet of amoxicillin intended for once-daily administration