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# Zinc
## Overview
Zinc is an essential trace element required for protein synthesis, wound healing, immune function, and DNA synthesis. Zinc gluconate, sulfate, and acetate are the most common supplemental salts. Elemental zinc content varies by salt (e.g., zinc sulfate 220 mg contains ~50 mg elemental zinc).
## Primary Indications
* Treatment/prevention of zinc deficiency.
* Adjunctive therapy for persistent infantile diarrhea (WHO/UNICEF recommendation).
* Wilson’s disease (zinc acetate).
## Adult Dosing
* **Deficiency (Elemental Zinc):** 25–50 mg elemental zinc daily.
* **Wilson’s Disease:** 50 mg elemental zinc 3 times daily (must be taken at least 1 hour apart from other medications/food).
* **Upper Limit (UL):** 40 mg elemental zinc/day from all sources (supplements + diet) to avoid toxicity. High-dose therapy (>50 mg/day) should be short-term unless medically supervised.
## Pediatric Dosing
* **Acute Diarrhea (WHO Recommendation):** 10 mg/day (for infants <6 months) or 20 mg/day (for children 6 months and older) for 10–14 days.
* **Deficiency:** 0.5–1.0 mg/kg/day elemental zinc, typically not exceeding 20–30 mg/day. Consult local institutional protocols for specific pediatric concentrations.
## Dose Adjustments
* **Hepatic/Renal Impairment:** No standard adjustments, but monitor closely for accumulation in patients with severe hepatic impairment.
* **Wilson’s Disease:** Dosing is titration-based; serum and urinary zinc levels guide maintenance.
## Contraindications
* Hypersensitivity to zinc salts.
* Current copper deficiency (may exacerbate depletion).
## Adverse Effects
* **Gastrointestinal:** Nausea, vomiting, epigastric pain, metallic taste (most common with empty stomach).
* **Chronic Toxicity:** Copper deficiency (manifesting as anemia, neutropenia, and neurological symptoms), potential risk of hypocalcemia or iron deficiency.
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Zinc reduces absorption of these antibiotics; separate doses by at least 2–4 hours.
* **Penicillamine:** Zinc significantly reduces penicillamine absorption.
* **Iron Supplements:** Concurrent high-dose iron may impair zinc absorption.
## Monitoring
* **Long-term use:** Monitor serum zinc, copper, and ceruloplasmin levels.
* **Symptomatic:** Assess for signs of gastrointestinal distress or anemia/neutropenia.
## Clinical Pearls
* **Bioavailability:** Zinc acetate is often chosen for Wilson's disease due to better tolerability. Zinc sulfate is cheap but high doses are prone to causing gastric irritation.
* **Absorption:** Best taken with food to reduce GI upset; however, food (particularly phytates and calcium) can reduce bioavailability. Consistency is key.
* **Copper Depletion:** Long-term, high-dose zinc supplementation (typically >50 mg elemental zinc/day) creates a high risk of copper deficiency via induction of intestinal metallothionein, which traps copper in mucosal cells.
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*Disclaimer: This information is for educational purposes. Clinical protocols and local standard-of-care guidelines vary. Always consult the most recent package insert, internal institutional guidelines, or a clinical pharmacist before prescribing or administering medication.*
