Succimer
Succimer (DMSA) is an oral heavy metal chelating agent primarily utilized in veterinary medicine for the treatment of **lead poisoning** in small animals and birds. It is a water-soluble analog of dimercaprol (BAL) but offers the distinct advantage of oral administration and a significantly wider therapeutic index. * **Target Toxins:** Highly effective for lead (Pb); potentially beneficial for arsenic (As) and mercury (Hg) toxicosis. * **Safety Profile:** Generally safe and effective. It spares most essential trace elements (like zinc, copper, and iron) from being chelated and does not enhance lead absorption from the gastrointestinal tract. > **Clinical Pearl:** Succimer is often preferred over CaEDTA for lead poisoning in small animals because it can be given orally at home, is less nephrotoxic, and does not deplete essential minerals as aggressively.
Mechanism: Succimer acts as a heavy metal chelator through its **sulfhydryl (-SH) groups**. * **Binding:** The sulfhydryl groups physically bind (chelate) heavy metal ions (such as **lead, mercury, and arsenic**) in the bloodstream and tissues. * **Complex Formation:** Heavy metal + Succimer → **Water-soluble chelate complex**. * **Excretion:** These stable, water-soluble complexes are subsequently filtered by the kidneys and excreted safely in the urine, thereby reducing the heavy metal burden in the body.
Dosing by species
- Lead poisoning · 10 mg/kg PO three times daily for 5 days, followed by 10 mg/kg PO twice daily for 2 weeks · PO · TID then BID · 19 days
- Lead poisoning · 10 mg/kg PO q8h · PO · q8h · 10 days · Blood lead levels should be rechecked a few days following the last dose; a second round may be necessary.
- Lead poisoning · 15-35 mg/kg PO twice daily · PO · BID · 5 days
- Lead poisoning · 30 mg/kg PO twice daily · PO · BID · minimum of 7 days · If severe neurologic signs, may supplement with one dose of CaEDTA (<50 mg/kg IM).
- Lead poisoning · 10 mg/kg PO q8h · PO · q8h · 10 days · Blood lead levels should be rechecked a few days following the last dose; a second round may be necessary.
- Lead poisoning · 10 mg/kg PO three times daily for 5 days, followed by 10 mg/kg PO twice daily for 2 weeks · PO · TID then BID · 19 days
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Hypersensitivity to succimer
- Continued exposure to the lead source (source must be removed prior to or concurrently with therapy)
Adverse effects
- Gastrointestinal upset (vomiting, diarrhea)
- Flu-like symptoms (fatigue, body aches)
- Increased liver enzymes (AST, ALT)
- Rash
- Unpleasant sulfurous odor imparted to breath, saliva, urine, and feces
Drug interactions
- Other chelating agents (CaEDTA, dimercaprol, trientine, penicillamine) · Concomitant use is not recommended in humans due to potential for increased toxicity or altered efficacy.
Monitoring
- Blood lead levels (recheck a few days after completing therapy)
- Gastrointestinal adverse effects
- Liver enzymes (AST, ALT)
- Hydration status
Overdose
### Overdose & Toxicity * **Dogs:** Succimer has a relatively wide margin of safety. Doses up to 200 mg/kg/day did not cause overt toxicity. However, massive doses (300 mg/day) caused fatalities, primarily presenting with **kidney and GI tract lesions**. * **Birds:** Cockatiels are particularly sensitive to high doses. Doses of 80 mg/kg PO q12h caused a significant number of fatalities, whereas 40 mg/kg q12h did not. * **Treatment:** If an acute overdose occurs, standardized gut evacuation (emesis/lavage) followed by activated charcoal protocols are recommended.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.