SUMER 100MG

Indications

• Lead poisoning
• Mercury poisoning
• Cadmium poisoning
• Arsenic poisoning

Dosage

Adults: The usual dosage for adults is 10 mg/kg orally every 8 hours for 5 days, followed by 10 mg/kg every 12 hours for 14 days.

Mechanism of action

Succimer acts as a heavy metal chelator by binding with high specificity to lead ions, forming water-soluble complexes that enhance their urinary excretion. The chelation involves coordination of sulfur and oxygen atoms from succimer with lead ions. The solubility of the chelates is influenced by the ionization of thiol and carboxylic acid groups in succimer. It also undergoes biotransformation to form mixed disulfides, primarily with L-cysteine, which are then excreted in altered forms.

Pharmacodynamics

As an effective chelating agent, succimer increases the urinary excretion of lead, thereby reducing the body's burden of this toxic metal. It is not effective for the prevention of lead poisoning in individuals who are regularly exposed to lead. The therapeutic effects of succimer are contingent upon the prompt identification and removal of the lead source to prevent further exposure.

Pharmacokinetics

Succimer is well absorbed when administered orally. After administration, it is biotransformed into various altered forms, with only a small percentage excreted unchanged. The majority of the altered succimer in urine appears as mixed disulfides with L-cysteine. Typically, 2.5% of the administered dose is excreted as unaltered succimer while 18.1% is detected as altered forms. The pharmacokinetics of succimer may vary based on individual patient factors and the presence of other medications.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Rash
• Fever
• Liver function abnormalities
• Neutropenia

Interactions

• May enhance the nephrotoxic effects of other drugs that are also nephrotoxic
• Caution with other heavy metal chelators as they may interact

Precautions

• Monitor renal function during therapy
• Use with caution in patients with a history of hypersensitivity to succimer or its components
• Ensure that lead exposure is minimized or eliminated while using succimer

Pregnancy

Succimer should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Consult relevant guidelines.

Breast-feeding

It is not known whether succimer is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Protect from light.

Formulations

• Capsules
• Oral suspension

Mechanism of action

Succimer is a heavy metal chelator. It binds with high specificity to ions of lead in the blood to form a water-soluble complex that is subsequently excreted by the kidneys. Succimer can also chelate mercury, cadmium, and arsenic in this manner. Succimer is a lead chelator; it forms water soluble chelates and, consequently, increases the urinary excretion of lead. DMSA chelates by coordination of one sulfur and one oxygen atom with Pb. Solubility of the lead chelates depends on the ionization of the noncoordinated thiol and carboxylic acid groups. Bimane derivatization, HPLC, and fluorescence, as well as gas chromatography can be used for analysis of DMSA in biological fluids. The acid dissociation constants for meso- and racemic-DMSA have been summarized from the literature as have the formation constants of some of the DMSA chelates. DMSA is biotransformed to a mixed disulfide in humans. By 14 hr after DMSA administration (10 mg/kg), only 2.5% of the administered DMSA is excreted in the urine as unaltered DMSA and 18.1% of the dose is found in the urine as altered forms of DMSA. Most altered DMSA in the urine is in the form of a mixed disulfide. It consists of DMSA in disulfide linkages with two molecules of L-cysteine. One molecule of cysteine is attached to each of the sulfur atoms of DMSA. The remaining 10% of the altered DMSA was in the form of cyclic disulfides of DMSA. So far, the mixed disulfide has been found in human but not in rabbit, mouse, or rat urine. Apparently there are species differences in how organisms metabolize meso-DMSA.

Pharmacodynamics

Succimer is an orally active, heavy metal chelating agent. It forms water soluble chelates and, consequently, increases the urinary excretion of lead. Succimer is not to be used for prophylaxis of lead poisoning in a lead-containing environment. In addition, the use of succimer should always be accompanied by identification and removal of the source of the lead exposure.