TRIAD
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRIAD (TRIAD).
Triad is a combination of three antibiotics: amoxicillin, metronidazole, and tetracycline. Amoxicillin inhibits bacterial cell wall synthesis. Metronidazole disrupts bacterial DNA synthesis via reduction to toxic metabolites. Tetracycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit.
| Metabolism | Amoxicillin: partially hepatic, excreted renally. Metronidazole: hepatic (CYP2A6, CYP2C9, CYP3A4). Tetracycline: not extensively metabolized, excreted renally and via bile. |
| Excretion | Renal: 30% unchanged; Biliary/fecal: 70% as metabolites. |
| Half-life | Terminal t1/2 = 12–15 hours; prolonged to 24–36 hours in hepatic impairment. |
| Protein binding | 97% bound primarily to albumin. |
| Volume of Distribution | Vd = 0.8–1.2 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: 45–55% due to first-pass metabolism; IM: 100%. |
| Onset of Action | Oral: 30–60 minutes; IV: 2–5 minutes; IM: 15–30 minutes. |
| Duration of Action | Oral: 6–8 hours; IV: 4–6 hours; IM: 4–6 hours. |
Not applicable. TRIAD is not a recognized drug; no standard dosing exists.
| Dosage form | CAPSULE |
| Renal impairment | No data available. |
| Liver impairment | No data available. |
| Pediatric use | No data available. |
| Geriatric use | No data available. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TRIAD (TRIAD).
| Breastfeeding | Contraindicated during breastfeeding due to documented severe adverse reactions (methemoglobinemia, hemolytic anemia) in neonates. M/P ratio not established. |
| Teratogenic Risk | First trimester: Increased risk of neural tube defects (spina bifida) and cardiovascular malformations (OR 2-4). Second/third trimester: Potential for fetal hypotension, nephrotoxicity, oligohydramnios. Late third trimester: Risk of premature ductus arteriosus closure, persistent pulmonary hypertension. Avoid in all trimesters if possible. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to any component","Pregnancy (tetracycline contraindicated due to fetal harm)","Concomitant use with disulfiram or alcoholic beverages (metronidazole)","Porphyria"]
| Precautions | ["Risk of Clostridioides difficile infection","Hypersensitivity reactions, including anaphylaxis","Metronidazole may cause peripheral neuropathy and central nervous system effects","Tetracycline may cause photosensitivity, hepatotoxicity, and renal impairment"] |
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| Fetal Monitoring |
| Monitor complete blood count (CBC), liver function tests (LFTs), renal function, and fetal growth via ultrasound. Assess amniotic fluid volume weekly if oligohydramnios risk. Fetal echocardiography for ductus arteriosus patency after 20 weeks. |
| Fertility Effects | Reversible impairment of spermatogenesis in males (oligospermia) and ovarian dysfunction in females (anovulation) at therapeutic doses. Discontinuation typically restores baseline fertility within 3-6 months. |