LYMEPAK
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LYMEPAK (LYMEPAK).
Lyme disease treatment: Antibiotic combination (amoxicillin/clavulanate) inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, disrupting peptidoglycan cross-linking. Clavulanate is a beta-lactamase inhibitor that prevents degradation of amoxicillin by bacterial enzymes.
| Metabolism | Amoxicillin: Partially hepatic metabolism, primarily renal excretion (60-70% unchanged). Clavulanate: Hepatic metabolism to inactive metabolites, renal excretion. |
| Excretion | Primarily renal (70-80% unchanged), with biliary/fecal elimination accounting for 15-20%. |
| Half-life | Terminal elimination half-life 12-18 hours; prolonged in renal impairment requiring dose adjustment. |
| Protein binding | 98% bound to serum albumin. |
| Volume of Distribution | Vd 0.3-0.4 L/kg, indicating distribution primarily in extracellular fluid. |
| Bioavailability | Oral bioavailability 70-80%. |
| Onset of Action | Oral: ~1-2 hours; intravenous: within 30 minutes. |
| Duration of Action | Clinical effect persists for 12-24 hours, supporting twice-daily dosing. |
100 mg orally twice daily for 18 days, plus 500 mg probenecid orally three times daily for 18 days.
| Dosage form | TABLET |
| Renal impairment | CrCl 10-30 mL/min: 100 mg orally every 48 hours; CrCl <10 mL/min: 100 mg orally every 96 hours. |
| Liver impairment | No specific guidelines; use with caution in severe impairment (Child-Pugh C). |
| Pediatric use | Children >8 years: 4 mg/kg (max 100 mg) orally twice daily for 18 days, plus probenecid 25 mg/kg (max 500 mg) three times daily. |
| Geriatric use | No specific adjustment; consider renal function and monitor for adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LYMEPAK (LYMEPAK).
| Breastfeeding | Doxycycline is excreted in human milk at low concentrations (M/P ratio unknown). Theoretical risk of dental staining and bone growth suppression in nursing infants. Ceftriaxone is excreted in low amounts in breast milk (M/P ratio approximately 0.01). Consider alternative therapy, especially for prolonged use. Use with caution, monitoring infant for rash, diarrhea, and candidiasis. |
| Teratogenic Risk | LYMEPAK (doxycycline and ceftriaxone) is contraindicated in pregnancy due to doxycycline's FDA Pregnancy Category D. First trimester: risk of teratogenicity (neural tube defects, cardiovascular malformations) based on animal studies. Second and third trimesters: irreversible fetal bone and teeth discoloration, enamel hypoplasia, and skeletal growth retardation. Ceftriaxone is FDA Pregnancy Category B, with no adequate studies in pregnant women; use only if clearly needed. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to penicillins, cephalosporins, or other beta-lactams; history of cholestatic jaundice or hepatic dysfunction with amoxicillin/clavulanate; severe renal impairment (CrCl <30 mL/min) without dose adjustment.
| Precautions | Hypersensitivity reactions including anaphylaxis; severe cutaneous adverse reactions (SCARs); antibiotic-associated diarrhea (Clostridioides difficile infection); hepatotoxicity; seizures with high doses or renal impairment; use with caution in patients with mononucleosis (rash risk). |
Loading safety data…
| Fetal Monitoring | Pregnancy test before initiation. Ultrasound monitoring for fetal anomalies if exposure occurs. Monitor liver function tests, renal function, and complete blood count during prolonged therapy. Assess for signs of maternal allergy, pseudomembranous colitis, or Jarisch-Herxheimer reaction. In infants, monitor for bone and teeth effects if exposed via breast milk. |
| Fertility Effects | Doxycycline may cause reduced sperm motility and reversible impairment of spermatogenesis in animal studies. Ceftriaxone has no known significant effects on fertility. Combined effect unknown. Data limited; advise patients planning pregnancy to use alternative antibiotics. |