BETAINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BETAINE (BETAINE).
Betaine acts as a methyl group donor in the remethylation of homocysteine to methionine, via betaine-homocysteine methyltransferase (BHMT). This reduces homocysteine levels, particularly in homocystinuria.
| Metabolism | Betaine is metabolized via betaine-homocysteine methyltransferase (BHMT) in the liver and kidneys; also undergoes oxidation to dimethylglycine and further to sarcosine and glycine. |
| Excretion | Renal: approximately 80% as betaine and its metabolite dimethylglycine; fecal: <5%; biliary: negligible. |
| Half-life | Terminal elimination half-life is approximately 14-16 hours in adults with normal renal function; may be prolonged in renal impairment. |
| Protein binding | Minimal (<10%); primarily binds to albumin. |
| Volume of Distribution | Approximately 0.6 L/kg; indicates distribution primarily in total body water. |
| Bioavailability | Oral: >90% (well absorbed from gastrointestinal tract). |
| Onset of Action | Oral: 2-3 hours for reduction in plasma homocysteine levels; peak effect at 4-6 weeks of continuous therapy. |
| Duration of Action | Duration of homocysteine-lowering effect persists for 24-48 hours after a single dose; chronic therapy maintains reduced levels with consistent dosing. |
Oral: 3 g twice daily (6 g/day total). Administer with food.
| Dosage form | FOR SOLUTION |
| Renal impairment | No dosage adjustment required for renal impairment. Use caution in severe renal impairment due to potential electrolyte disturbances. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | Neonates and children: 100-250 mg/kg/day divided into 2-3 doses, titrated to plasma homocysteine levels. Maximum dose: 6 g/day. |
| Geriatric use | No specific adjustments. Start at lower end of dosing range due to possible renal decline and monitor plasma homocysteine levels. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BETAINE (BETAINE).
| Breastfeeding | Betaine is naturally present in breast milk. Exogenous betaine supplementation is likely excreted into breast milk, but data on M/P ratio are unavailable. Caution is advised; consider benefits versus risks. |
| Teratogenic Risk | Betaine is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. Animal studies have not been reported. Betaine is an endogenous metabolite and is generally considered low risk, but specific fetal risks by trimester are not defined. Use only if clearly needed. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to betaine or any component of the formulation"]
| Precautions | ["Hyperhomocysteinemia rebound upon discontinuation","Monitor plasma methionine and homocysteine levels; excessive methionine accumulation may occur"] |
| Food/Dietary | No significant food interactions. However, to minimize GI side effects, administer with meals. Avoid excessive intake of foods high in betaine (e.g., beets, spinach, shellfish) unless clinically indicated, as they may contribute to variable blood levels. |
| Clinical Pearls |
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| Fetal Monitoring |
| Monitor homocysteine levels, renal function, and serum electrolytes during therapy. In pregnancy, monitor fetal growth and development via ultrasound if indicated, and assess maternal liver function. |
| Fertility Effects | No known adverse effects on fertility. Betaine is used as a methyl donor and may support reproductive function by reducing homocysteine, but specific fertility data are lacking. |
| Betaine (trimethylglycine) is used as adjunctive therapy for homocystinuria to reduce homocysteine levels via remethylation. Monitor serum methionine as betaine can cause hypermethioninemia. Avoid in patients with severe renal impairment. Onset of effect may take weeks. Dosing is typically 3-6 g/day in divided doses, with titration based on homocysteine levels. |
| Patient Advice | Take betaine exactly as prescribed; do not stop without consulting your doctor. · Betaine may cause gastrointestinal upset; take with food to reduce nausea or diarrhea. · Regular blood tests are needed to monitor homocysteine and methionine levels. · Report symptoms of hypermethioninemia such as confusion, headache, or vision changes. · Do not take additional betaine supplements or other products containing betaine without medical advice. · If a dose is missed, take it as soon as remembered unless near the next dose; do not double the dose. |