Generic Name

Zinc sulfate

Mechanism

Zinc sulfate is a *phytometabolite* that restores systemic zinc levels. Its principal pharmacologic action involves:
• Enzyme cofactor: Serves as a catalytic cofactor for >300 enzymes, notably DNA polymerase, RNA polymerase, and alkaline phosphatase, thereby supporting cellular proliferation and nucleic acid synthesis.
• Antioxidant and anti‑inflammatory: Scavenges reactive oxygen species and inhibits NF‑κB activation, reducing cytokine production during infections and inflammatory states.
• Neurotransmission: Modulates glutamatergic and GABAergic signaling, partially explaining its calming effects in restless leg syndrome.

Thus, zinc sulfate corrects biochemical deficits and improves host defense, metabolic function, and neurohormonal regulation.

Pharmacokinetics

• Absorption: Peak plasma concentration 30–90 min post‑oral dose; ~20–30 % bioavailability; absorption significantly diminished by food, calcium, iron, and phytic acid.
• Distribution: Widely distributed; binds to albumin and transferrin; crosses the blood‑brain barrier to a limited extent.
• Metabolism: Not substantially metabolized; largely unchanged.
• Elimination: Renal excretion; half‑life ≈8–12 h in healthy adults; prolongs to 24 h in renal impairment.

*Clinical tip*: Administer on an empty stomach or 2 h after meals to maximize uptake.

Indications

• Zinc deficiency (e.g., kwashiorkor, alcoholism, malabsorption syndromes).
• Acute rhinitis and viral upper respiratory infections (adjunct therapy).
• Restless leg syndrome (low‑dose).
• Topical use: Ulcer healing, dermatitis, acne, and minor wound care (for non‑oral preparations).
• Adjunct in Crohn’s disease and ulcerative colitis: Improves malabsorption.

Contraindications

• Contraindications: None absolute; avoid in patients with known hypersensitivity to zinc.
• Warnings:
• *Copper deficiency*: Chronic high‑dose zinc can precipitate copper deficiency → anemia, neutropenia.
• *Renal disease*: Dose adjustment required; monitor serum creatinine.
• *Pregnancy/lactation*: Generally safe; use lowest effective dose.
• *Drug interactions*: Chelates with antibiotics (e.g., tetracyclines, fluoroquinolones), PPIs, diuretics, and iron supplements.

Dosing

*For children*: 0.5–1 mg/kg elemental zinc; adjust based on weight and clinical context.

Adverse Effects

• Common – metallic taste, nausea, abdominal cramping, diarrhea, headache.
• Serious – prolonged use may cause copper deficiency anemia, leukopenia; rare hypersensitivity rash or anaphylaxis.
• Drug‑induced – interference with absorption of doxycycline, ciprofloxacin, or oral iron; avoid concurrent ingestion.

Monitoring

• Serum zinc (baseline, 2–4 weeks, then every 3–6 months for chronic therapy).
• Copper (baseline; repeat if >3 months of therapy).
• Renal function (creatinine, eGFR) in patients with CKD or using >30 mg/day.
• CBC (monitor for anemia or neutropenia with prolonged high‑dose use).
• Growth parameters and developmental milestones in pediatric patients.

Clinical Pearls

• Optimize absorption: 30 min pre‑meal dosing beats "with food" timing, especially for patients on PPIs.
• “Zinc lock” phenomenon: A 10‑day gap between zinc and doxycycline decreases antibacterial activity; space doses by ≥2 h.
• Low‑dose for restless leg: 5–10 mg elemental zinc per day beats higher doses in reducing symptom severity without GI toxicity.
• Topical paradox: While oral zinc can cause diarrhea, topical 1–2 % solutions rarely affect systemic levels—ideal for skin ulcers and minor burns.
• Dual deficiency alert: In patients transitioning from zinc‑rich diets to low‑protein diets (e.g., post‑bariatric surgery), screen for copper deficiency to avoid a “double hit” on hematological function.

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• *This drug card provides a quick, evidence‑based reference for medical students and clinicians seeking to understand and apply zinc sulfate therapy.*