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# Zinc
## Overview
Zinc is an essential trace element required for protein synthesis, wound healing, immune function, and DNA synthesis. It exists as various salt formulations (e.g., gluconate, sulfate, acetate), which differ in elemental zinc content.
## Primary Indications
* Treatment/prevention of zinc deficiency.
* Adjunct therapy for Wilson’s disease (zinc acetate).
* Enteral/parenteral nutrition additive.
* Off-label: Reduction in duration/severity of common cold (if administered within 24 hours of symptom onset).
## Adult Dosing
* **Deficiency:** 25–50 mg elemental zinc daily, divided into 1–3 doses.
* **Wilson’s Disease (Zinc Acetate):** 50 mg elemental zinc orally 3 times daily.
* **Dietary Supplementation:** Recommended Dietary Allowance (RDA) is 11 mg (men) or 8 mg (women) daily.
* **Maximum:** Tolerable Upper Intake Level (UL) is 40 mg of elemental zinc daily for chronic use. Higher doses (up to 150 mg/day) are used clinically under provider supervision.
## Pediatric Dosing
* **Deficiency:** 0.5–1 mg/kg/day of elemental zinc.
* **Wilson’s Disease:** 25 mg 3 times daily (for weight > 30 kg); 25 mg twice daily (for weight 10–30 kg).
* **Dietary RDA:** Varies by age (e.g., 2 mg for infants 0–6 months; 8 mg for children 9–13 years). Consult local institutional guidelines for specific parenteral nutrition pediatric requirements.
## Dose Adjustments
* **Renal Impairment:** No standard adjustment; use with caution. Zinc is primarily excreted in feces; renal clearance is minimal.
* **Hepatic Impairment:** No specific criteria; monitor for accumulation in severe hepatic dysfunction.
## Contraindications
* Hypersensitivity to any component of the formulation.
* Avoid long-term high-dose therapy without monitoring plasma zinc or copper levels.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal cramps, metallic taste.
* **Serious (Chronic High-Dose):** Copper deficiency (manifesting as anemia, neutropenia, and neurological symptoms), suppressed immune function, impaired HDL-cholesterol levels.
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Zinc forms insoluble chelates; separate administration by at least 2–4 hours.
* **Penicillamine:** Zinc inhibits the absorption of penicillamine; separate by 2–4 hours.
* **Copper:** High-dose zinc induces intestinal metallothionein, which traps copper and prevents its absorption, leading to hypocupremia.
## Monitoring
* **Serum Zinc:** Generally unreliable due to poor sensitivity/specificity.
* **Serum Copper and Ceruloplasmin:** Essential if chronic high-dose zinc therapy is utilized to prevent secondary copper deficiency.
* **Hemoglobin/Hematocrit:** Monitor for signs of anemia (secondary to copper deficiency).
## Clinical Pearls
* **Elemental Content:** Always verify the elemental zinc content of the specific salt (e.g., Zinc sulfate 220 mg contains ~50 mg elemental zinc; Zinc gluconate 50 mg contains ~7 mg elemental zinc).
* **Administration:** Take with meals if gastric distress occurs, but note that phytates (in grains/legumes) and calcium may reduce absorption.
* **Common Cold:** If using for the common cold, lozenges are preferred, but monitor for mouth irritation; avoid intranasal forms due to potential irreversible loss of smell (anosmia).
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**Educational Disclaimer:** This information is for educational purposes only. Always verify dosages, contraindications, and drug interactions using current, institutional-specific reference materials or clinical decision support tools (e.g., Lexicomp, Micromedex) before prescribing or administering medication.
