Recommended Dosage of Zinc Sulfate
For Wilson's disease, adults and children over 50 kg should receive 150 mg elemental zinc daily divided into three doses (50 mg three times daily), while children under 50 kg require 75 mg elemental zinc daily in three divided doses, taken 30 minutes before meals. 1
Dosing by Indication and Population
Wilson's Disease (Primary Indication for Zinc Sulfate)
Adults and larger children (>50 kg body weight):
- 150 mg elemental zinc daily in three divided doses (50 mg three times daily) 1
- Must be taken at least twice daily to be effective; three times daily is optimal 1, 2
- Administer 30 minutes before meals to maximize absorption 1
Children under 50 kg:
- 75 mg elemental zinc daily in three divided doses (25 mg three times daily) 1
- For children 1-5 years: 25 mg twice daily 3
- For children 6-15 years (under 125 pounds): 25 mg three times daily 3
- Children under 5 years: dosing not well-defined but 25 mg twice daily has been used successfully 1, 4
Critical timing consideration: Taking zinc with food interferes with absorption and treatment effectiveness, though dose adjustments can compensate if timing around meals improves compliance 1
Parenteral Nutrition Supplementation (IV Zinc)
Adults:
- Metabolically stable: 3 mg/day 5
- Acute catabolic states: additional 2 mg/day 6
- Small bowel fluid loss: additional 12.2 mg/liter of fluid lost 6
- Stool/ileostomy output: additional 17.1 mg/kg of output 6
Pediatric patients (IV):
- Children ≥10 kg: 50 mcg/kg/day (maximum 3 mg/day) 5
- Children 5-10 kg: 100 mcg/kg/day 5
- Term neonates 3-5 kg: 250 mcg/kg/day (higher requirements in first 3 months) 5
- Preterm neonates <3 kg: 400 mcg/kg/day 5
Salt Formulation Considerations
The actual zinc salt used does not affect efficacy for Wilson's disease but may impact tolerability: 1
- Zinc acetate and gluconate may be more tolerable than sulfate for gastrointestinal side effects 1
- Individual variation exists; some patients tolerate sulfate well 1
- Organic compounds (gluconate, acetate, orotate) generally have better tolerability than inorganic forms 7
Monitoring Requirements
Treatment adequacy should be assessed by: 1
- Clinical and biochemical improvement
- 24-hour urinary copper excretion: should be <75 mcg (1.2 μmol) per 24 hours on stable treatment 1
- Non-ceruloplasmin bound copper: should normalize with effective treatment 1
- Urinary zinc excretion: measured periodically to check compliance 1
Critical Safety Warnings
Renal impairment: The safety of high-dose zinc in patients with impaired renal function is not established 1, 5
Drug interactions: If copper chelators (penicillamine, trientine) are co-administered, zinc must be dosed 5-6 hours apart to avoid neutralization of efficacy 1
Minimum effective dosing: 75 mg elemental zinc daily is the minimum effective dose, and it must be divided into at least two doses daily to maintain efficacy 2
Special Populations
Pregnancy:
- Zinc dosage is maintained throughout pregnancy without change 1
- Treatment must not be interrupted during pregnancy as this has resulted in acute liver failure 1
Decompensated cirrhosis:
- Combination regimen: 50 mg elemental zinc (25 mg in children) as first and third doses, with chelator as second and fourth doses, spaced 5-6 hours apart 1
- This is an intensive induction regimen requiring close monitoring 1
Common Pitfalls to Avoid
- Do not confuse elemental zinc with zinc salt weight: Dosing is always in milligrams of elemental zinc, not the total weight of the zinc compound 1
- Do not use once-daily dosing: Even with adequate total daily dose, once-daily administration is ineffective 2
- Do not skip monitoring: Patients on doses exceeding usual maintenance require frequent zinc blood level monitoring 6
- Do not use in acute liver failure: Zinc is not appropriate for acute Wilsonian liver failure; these patients require transplantation 1