Zinc

# Zinc ## Overview - **Classification**: Essential trace element, mineral supplement. - **Mechanism**: Critical cofactor for over 300 enzymes. Involved in immune function, wound healing, DNA synthesis, protein synthesis, and cell division. ## Primary Indications 1. **Zinc Deficiency**: Treatment and prevention of various deficiency states. 2. **Acute Diarrhea (Children)**: Adjunctive therapy to reduce duration and severity. 3. **Age-related Macular Degeneration (AMD)**: Used in specific antioxidant formulations to slow disease progression. 4. **Wound Healing**: Adjunct in chronic wound care, especially in deficient patients. ## Adult Dosing ### Standard Dosing **Zinc Deficiency (Mild to Moderate)** - **Dose**: **30-60 mg elemental zinc** (e.g., 220 mg zinc sulfate heptahydrate provides 50 mg elemental zinc) - **Frequency**: Once daily - **Route**: Oral - **Duration**: Until deficiency is resolved, then maintenance if needed. **Acute Diarrhea (Adjunctive)** - **Dose**: **20 mg elemental zinc** - **Frequency**: Once daily - **Route**: Oral - **Duration**: 10-14 days **Age-related Macular Degeneration (AMD)** - **Dose**: **80 mg elemental zinc** (as part of AREDS/AREDS2 formulations) - **Frequency**: Once daily - **Route**: Oral - **Duration**: Long-term as per clinical trial guidelines. **Wound Healing (Adjunctive, especially with deficiency)** - **Dose**: **50 mg elemental zinc** - **Frequency**: 2-3 times daily - **Route**: Oral - **Duration**: As needed for healing, with monitoring. ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment generally required. - **Hepatic Impairment**: No specific dose adjustment generally required. - **Elderly Patients**: No specific dose adjustment. Monitor for copper deficiency with prolonged high-dose use. ## Pediatric Dosing *Note: Doses are for elemental zinc.* ### Neonates (0-28 days) **Zinc Deficiency (e.g., TPN Supplementation)** - **Dose**: **300 mcg/kg/day** (preterm <3 kg); **250 mcg/kg/day** (term ≥3 kg) - **Frequency**: Once daily - **Maximum**: Individualized based on clinical status and TPN regimen. - **Special Notes**: Typically administered via parenteral nutrition. Close monitoring of zinc and copper levels is crucial. ### Infants (1-12 months) **Acute Diarrhea (Adjunctive, WHO recommendation)** - **Dose**: **10 mg elemental zinc** - **Frequency**: Once daily - **Maximum**: **10 mg/day** for this indication. - **Special Notes**: Oral solution or dispersible tablets are preferred. Administer for 10-14 days. **Zinc Deficiency** - **Dose**: **0.5-1 mg/kg/day elemental zinc** - **Frequency**: Once daily - **Maximum**: **10 mg/day** for general supplementation. Higher doses for severe deficiency under medical supervision. ### Children (1-12 years) **Acute Diarrhea (Adjunctive, WHO recommendation)** - **Dose**: **20 mg elemental zinc** - **Frequency**: Once daily - **Maximum**: **20 mg/day** for this indication. **Zinc Deficiency** - **Dose**: **0.5-1 mg/kg/day elemental zinc** - **Frequency**: Once daily - **Maximum**: **20-40 mg/day** depending on severity. Consult a specialist for doses exceeding 40 mg/day. ### Adolescents (13-18 years) - **Dose**: Generally follows **adult dosing** guidelines for specific indications. - **Maximum**: **40 mg/day elemental zinc** (Tolerable Upper Intake Level) for general supplementation. Higher doses for deficiency treatment under medical supervision. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to zinc preparations. - **Relative**: Acute kidney injury (use with caution, though accumulation is rare). - **Relative**: Long-term high-dose use in patients without confirmed deficiency (risk of copper deficiency). ### Common Adverse Effects - **Common (1-10%)**: Nausea, vomiting, abdominal pain, diarrhea, dyspepsia. - **Serious but Rare**: Copper deficiency (with prolonged high-dose zinc), sideroblastic anemia, leukopenia. - **Serious but Rare**: Metallic taste, oral irritation (with lozenges). ### Key Drug Interactions - **Tetracyclines (e.g., Doxycycline)**: Zinc can chelate tetracyclines, reducing absorption. Separate doses by at least **2-3 hours**. - **Fluoroquinolones (e.g., Ciprofloxacin)**: Zinc can chelate fluoroquinolones, reducing absorption. Separate doses by at least **2-3 hours**. - **Penicillamine**: Zinc can decrease penicillamine absorption. Administer at different times. - **Calcium/Iron supplements**: Can compete for absorption with zinc. Consider separating doses by **2 hours**. ## Monitoring & Follow-up - **Before Treatment**: Baseline serum zinc levels if deficiency suspected. - **During Treatment**: Monitor serum zinc levels (especially with high dose/long-term), serum copper levels (long-term high dose), hemoglobin, and WBC counts. - **Clinical Signs**: Monitor for improvement in deficiency symptoms. Watch for GI upset, signs of copper deficiency (e.g., anemia, neutropenia). ## Clinical Pearls - 💡 **Tip 1**: Administer zinc with food to minimize GI upset. However, certain foods (e.g., high fiber, dairy, coffee) may reduce absorption. - 💡 **Tip 2**: Doses are based on **elemental zinc**. Check product labels carefully as elemental zinc content varies by salt (e.g., zinc sulfate, gluconate, picolinate). - 💡 **Tip 3**: Long-term zinc supplementation (>3 months) at doses >40 mg/day elemental zinc should include copper supplementation (e.g., **1-2 mg/day**) to prevent copper deficiency. - 💡 **Tip 4**: Zinc lozenges may reduce the duration of common cold symptoms, but efficacy is variable and GI upset is common. Nasal zinc products are associated with anosmia and should be avoided. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.