MOXATAG
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MOXATAG (MOXATAG).
Amoxicillin (extended-release) inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidation and autolysin inhibitors, leading to cell lysis and death via activation of autolytic enzymes.
| Metabolism | Amoxicillin is primarily metabolized by hydrolysis to penicilloic acid, which is then excreted renally. Minor metabolism via hepatic pathways. |
| Excretion | Approximately 60% of the dose is excreted unchanged in urine via glomerular filtration and tubular secretion; about 20% is excreted in feces via biliary elimination. |
| Half-life | The terminal elimination half-life is 1.0–1.5 hours in healthy adults; however, with the extended-release formulation (Moxatag), the effective half-life is prolonged to support once-daily dosing. |
| Protein binding | Approximately 20% bound to serum proteins, primarily albumin. |
| Volume of Distribution | 0.2–0.3 L/kg, indicating distribution primarily into extracellular fluid; clinical meaning: low Vd reflects limited tissue penetration. |
| Bioavailability | Oral bioavailability of amoxicillin is about 95% (range 74–92% for immediate-release); Moxatag ER has similar overall absorption but with extended-release characteristics. |
| Onset of Action | Oral: Peak serum concentrations are achieved in 1–2 hours for standard immediate-release; Moxatag extended-release reaches peak at approximately 3 hours. |
| Duration of Action | The extended-release formulation provides therapeutic concentrations for 24 hours, allowing once-daily administration for the treatment of pharyngitis/tonsillitis due to Streptococcus pyogenes. |
| Molecular Weight | 419.45 |
775 mg orally once daily for 7 days.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | For CrCl 30-60 mL/min: 775 mg orally once daily; for CrCl <30 mL/min: no data available, use with caution. For hemodialysis: not recommended. |
| Liver impairment | No adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B); no data for severe impairment (Child-Pugh C). |
| Pediatric use | Not approved for pediatric patients under 18 years. Safety and efficacy not established. |
| Geriatric use | No specific dose adjustment; however, consider renal function due to age-related decline. Use same dose as adults if normal renal function. |
| 1st trimester | Amoxicillin is generally considered safe in the first trimester based on extensive human data; no increased risk of major congenital malformations. However, use only if clearly needed. |
| 2nd trimester | Safe for use; no known risks. Preferred antibiotic for many infections during pregnancy. |
| 3rd trimester | Safe for use; no known fetal adverse effects. Near term, theoretical risk of neonatal diarrhea or candidiasis but minimal. |
Clinical note
Comprehensive clinical and safety monograph for MOXATAG (MOXATAG).
| Placental transfer | Amoxicillin crosses the placenta rapidly. Fetal serum levels reach approximately 30-50% of maternal levels. Placental transport is mediated by passive diffusion and active transport via OAT4 and OATP2B1. |
| Breastfeeding | Amoxicillin is excreted into breast milk in small amounts (<0.1% of maternal dose). Not expected to cause adverse effects in breastfed infants. Potential for alteration of infant gut flora or allergic reaction, but generally considered compatible. Monitor infant for diarrhea or rash. |
■ FDA Black Box Warning
None
| Common Effects | Nausea Diarrhea Skin rash Vomiting |
| Serious Effects |
Hypersensitivity to amoxicillin or any penicillin-class antibioticHistory of anaphylactic reaction to beta-lactams
| Precautions | Serious hypersensitivity reactions (anaphylaxis) reported; contraindicated in patients with known hypersensitivity to penicillins or cephalosporins., Clostridium difficile-associated diarrhea (CDAD) may occur; evaluate if diarrhea develops., Prolonged use may result in bacterial or fungal superinfection., Use with caution in patients with renal impairment; dose adjustment recommended for CrCl <30 mL/min., Not recommended for patients with mononucleosis due to high incidence of maculopapular rash. |
| Food/Dietary | Take MOXATAG with food to improve absorption and reduce GI upset. Avoid grapefruit juice as it may alter absorption. Food does not significantly affect overall bioavailability but does reduce GI adverse effects. No specific foods to avoid other than grapefruit. |
Loading safety data…
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | Teratogenic risk category B. No evidence of fetal harm in animal studies; no adequate human studies. Potential risk cannot be ruled out. Use only if clearly needed. |
| Fetal Monitoring | Monitor for maternal gastrointestinal disturbances, hypersensitivity reactions, and signs of superinfection. Fetal monitoring not routinely required. |
| Fertility Effects | No known adverse effects on fertility based on animal studies; human data lacking. |
| Clinical Pearls | MOXATAG (amoxicillin extended-release) is indicated for pharyngitis/tonsillitis due to Streptococcus pyogenes in adults and children ≥12 years. Administer with a meal to enhance absorption and reduce GI intolerance. Sustained-release formulation allows once-daily dosing. Ensure patient swallows tablet whole; do not crush or chew. Use with caution in patients with renal impairment (CrCl <30 mL/min: do not use). Monitor for signs of hypersensitivity, especially in patients with prior penicillin allergy. |
| Patient Advice | Take MOXATAG once daily with a meal at the same time each day. · Swallow the tablet whole; do not crush, chew, or split it. · Complete the full prescribed course even if you feel better to prevent resistance. · Common side effects include diarrhea, nausea, and rash; contact your doctor if severe or persistent. · Avoid taking with alcohol as it may worsen side effects. · Inform your doctor about all medications, especially oral contraceptives (may reduce efficacy), anticoagulants, or methotrexate. |