Introduction
Zinc is an essential trace mineral that serves as a critical cofactor for numerous enzymatic reactions and biological processes throughout the human body. As a pharmaceutical agent, zinc is available in various formulations including oral supplements, topical preparations, and intravenous solutions. Zinc plays vital roles in immune function, wound healing, DNA synthesis, cell division, and growth development.
Mechanism of Action
Zinc functions primarily as a cofactor for over 300 enzymes involved in protein synthesis, nucleic acid metabolism, and cellular replication. It stabilizes cell membranes and contributes to structural integrity of proteins and nucleic acids. Zinc supports immune function by facilitating T-lymphocyte activation and neutrophil function. In topical formulations, zinc exhibits mild astringent properties, promotes wound healing, and provides protective barrier functions.
Indications
- Treatment and prevention of zinc deficiency
- Wilson's disease (as adjunctive therapy)
- Acne vulgaris (topical formulations)
- Diaper rash and minor skin irritations (topical preparations)
- Common cold symptom reduction (lozenges)
- Wound healing (topical applications)
- Nutritional supplementation in conditions with increased requirements (pregnancy, lactation, malabsorption syndromes)
Dosage and Administration
Oral supplementation:- Adults: 15-30 mg elemental zinc daily for deficiency
- Wilson's disease: 50 mg elemental zinc three times daily (adults)
- Common cold: Zinc gluconate or acetate lozenges providing 13-23 mg zinc every 2 hours while awake
- Apply to affected areas 1-3 times daily
- Renal impairment: Dose adjustment may be necessary
- Hepatic impairment: Use with caution in Wilson's disease
- Pediatrics: 2-5 mg/kg/day for deficiency (maximum 50 mg/day)
Pharmacokinetics
Absorption: Zinc is absorbed primarily in the duodenum and jejunum (20-30% bioavailability). Absorption is enhanced by animal proteins and inhibited by phytates, calcium, iron, and copper. Distribution: Distributed throughout all body tissues with highest concentrations in prostate, liver, pancreas, kidney, bone, and muscles. Plasma zinc represents <0.1% of total body zinc. Metabolism: Not metabolized; functions as an ionic compound. Elimination: Primarily excreted in feces (via pancreatic and biliary secretions) and urine. Elimination half-life approximately 12 hours.Contraindications
- Hypersensitivity to zinc or product components
- Concurrent use with amiloride (in Wilson's disease patients)
Warnings and Precautions
- Chronic excessive intake (>40 mg/day) may cause copper deficiency and related hematological and neurological complications
- Use caution in patients with gastrointestinal disorders
- Nasal zinc products have been associated with permanent loss of smell and are not recommended
- May cause nausea and gastrointestinal irritation
- Monitor for copper deficiency during long-term high-dose therapy
Drug Interactions
- Quinolones and tetracyclines: Zinc reduces absorption of these antibiotics (separate administration by 2-4 hours)
- Penicillamine: Reduced absorption of both agents
- Iron supplements: Mutual inhibition of absorption
- Calcium supplements: May decrease zinc absorption
- Thiazide diuretics: May increase urinary zinc excretion
- ACE inhibitors: May cause taste disturbances
Adverse Effects
Common:- Gastrointestinal: Nausea, vomiting, epigastric pain, diarrhea
- Metallic taste
- Headache
- Copper deficiency (with prolonged high doses)
- Neutropenia
- Anemia
- Reduced immune function (with excessive intake)
- Renal impairment (with extremely high doses)
- Skin irritation
- Contact dermatitis
Monitoring Parameters
- Serum zinc levels (for deficiency treatment)
- Complete blood count (for long-term high-dose therapy)
- Copper and ceruloplasmin levels (during prolonged therapy)
- Renal function (with high-dose IV therapy)
- Clinical signs of copper deficiency
- Therapeutic response and symptom improvement
Patient Education
- Take oral zinc supplements with food to reduce gastrointestinal upset
- Do not exceed recommended doses unless directed by healthcare provider
- Separate zinc administration from antibiotics, iron, and calcium supplements by 2-4 hours
- Report persistent gastrointestinal symptoms or signs of infection
- For lozenges: Allow to dissolve completely in mouth; do not chew or swallow whole
- For topical products: Cleanse area before application; discontinue if irritation occurs
- Zinc is not a substitute for balanced nutrition
References
1. National Institutes of Health Office of Dietary Supplements. Zinc Fact Sheet for Health Professionals. 2021. 2. Prasad AS. Zinc: an overview. Nutrition. 1995;11(1 Suppl):93-99. 3. Hemilä H. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM Open. 2017;8(5):2054270417694291. 4. Brewer GJ, et al. Treatment of Wilson's disease with zinc: XV long-term follow-up studies. J Lab Clin Med. 1998;132(4):264-278. 5. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001. 6. Gupta M, et al. Zinc therapy in dermatology: a review. Dermatol Res Pract. 2014;2014:709152. 7. Plum LM, et al. The essential toxin: impact of zinc on human health. Int J Environ Res Public Health. 2010;7(4):1342-1365.