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Tuesday, August 5, 2025

Minerals and electrolytes


Introduction

Minerals and electrolytes are essential micronutrients and ions that support critical physiological functions including nerve conduction, muscle contraction, hydration, enzymatic reactions, pH balance, and cellular integrity. These agents are widely utilized across multiple therapeutic domains — including nephrology, cardiology, endocrinology, and intensive care — to correct deficiencies, maintain homeostasis, and support metabolic and biochemical stability.

This drug class encompasses agents like sodium, potassium, calcium, magnesium, chloride, phosphate, and trace elements such as zinc, selenium, copper, and chromium. Their pharmacological supplementation may occur through oral, parenteral, or intravenous routes depending on severity, etiology, and urgency of correction.

Pharmacological Classification of Minerals and Electrolytes

  1. Macrominerals (Major Minerals):

    • Sodium (Na⁺) – Osmotic regulation, nerve transmission

    • Potassium (K⁺) – Cardiac and neuromuscular activity

    • Calcium (Ca²⁺) – Bone metabolism, coagulation, muscle contraction

    • Magnesium (Mg²⁺) – ATP processing, nerve conduction, muscle relaxation

    • Phosphate (PO₄³⁻) – Energy metabolism, bone structure

    • Chloride (Cl⁻) – Osmotic balance, acid-base equilibrium

  2. Microminerals (Trace Elements):

    • Zinc (Zn) – Immune response, wound healing, DNA synthesis

    • Copper (Cu) – Iron metabolism, enzyme activation

    • Selenium (Se) – Antioxidant defense (glutathione peroxidase)

    • Chromium (Cr) – Glucose metabolism

    • Iron (Fe) – Hemoglobin synthesis and oxygen transport

    • Manganese, Iodine, Fluoride – Thyroid function, bone metabolism

Mechanism of Action

These agents do not act through receptor-mediated pathways typical of conventional drugs. Instead, they function as:

  • Cofactors for enzymatic reactions (e.g., magnesium for ATPases, zinc for polymerases)

  • Electrochemical agents for nerve transmission (e.g., sodium, potassium)

  • Structural components of bone and teeth (e.g., calcium, phosphate, fluoride)

  • Redox regulators in antioxidant systems (e.g., selenium, copper)

  • Osmotic regulators maintaining fluid distribution and blood pressure (e.g., sodium, chloride)

Therapeutic Uses

1. Sodium and Chloride:

  • Treatment of hyponatremia

  • Volume resuscitation in hypovolemia, shock

  • Electrolyte maintenance in parenteral nutrition

  • Sodium chloride nasal sprays for mucosal hydration

2. Potassium:

  • Management of hypokalemia from diuretics or GI loss

  • Cardioprotection in digitalis toxicity

  • Prevent arrhythmias in critically ill patients

3. Calcium:

  • Hypocalcemia, tetany, post-surgical hypoparathyroidism

  • Osteoporosis prevention and treatment

  • As an antidote in hyperkalemia and calcium channel blocker overdose

  • Calcium acetate used in hyperphosphatemia in CKD

4. Magnesium:

  • Treatment of hypomagnesemia

  • Seizure prophylaxis in eclampsia

  • Management of torsades de pointes, asthma exacerbations

5. Phosphate:

  • Hypophosphatemia correction

  • Phosphate binders used in hyperphosphatemia in dialysis patients

  • Component of bowel preparations

6. Zinc:

  • Treatment of zinc deficiency, especially in chronic diarrhea or malabsorption

  • Wound healing, age-related macular degeneration, Wilson’s disease (as acetate or sulfate)

7. Copper, Selenium, Chromium:

  • Trace element repletion in parenteral nutrition

  • Selenium in Keshan disease, thyroid disorders

  • Chromium as a potential adjunct in diabetes mellitus

8. Iron:

  • Iron-deficiency anemia treatment

  • Pre- and post-operative anemia management

  • Supplementation during pregnancy and menstruation

Dosage Forms and Routes of Administration

  • Oral: Tablets, capsules, syrups (e.g., potassium chloride, ferrous sulfate, calcium carbonate)

  • Parenteral/IV: For rapid correction or when oral route is contraindicated (e.g., magnesium sulfate IV in eclampsia)

  • Topical: Zinc oxide for dermatological use

  • Nasally or via irrigation: Sodium chloride sprays

  • Enteral/Parenteral nutrition solutions: Balanced electrolyte formulas

Dosing and Administration

Dosing is individualized based on serum levels, renal function, underlying disease, and route of administration. Examples include:

  • Potassium chloride (oral): 20–40 mEq/day in divided doses for prevention

  • Calcium gluconate (IV): 1–2 g over 10–20 minutes for acute hypocalcemia

  • Magnesium sulfate (IV): 1–2 g/hour infusion for preeclampsia or torsades

  • Ferrous sulfate (oral): 325 mg TID (provides ~65 mg elemental iron per dose)

  • Zinc sulfate: 220 mg orally once daily

Contraindications

  • Hyperkalemia: Avoid potassium supplements or potassium-sparing diuretics

  • Hypercalcemia: Avoid calcium supplements

  • Renal insufficiency: Caution with magnesium, potassium, phosphate

  • Hemochromatosis: Iron supplementation contraindicated

  • Wilson’s disease: Copper supplementation contraindicated

Adverse Effects

1. Gastrointestinal:

  • Iron: Constipation, dark stools, epigastric pain

  • Magnesium and potassium: Diarrhea, nausea

2. Electrolyte Disturbances:

  • Hyperkalemia: ECG changes, cardiac arrest

  • Hypercalcemia: Nausea, confusion, arrhythmias

  • Hypermagnesemia: Hypotension, bradycardia, loss of deep tendon reflexes

3. Injection-site reactions:

  • Phlebitis with IV potassium or calcium

  • Tissue necrosis with extravasation of calcium chloride

4. Other:

  • Zinc: Metallic taste, GI upset

  • Selenium: Hair loss, fatigue, garlic breath in toxicity

  • Iron: Risk of overdose in children

Drug Interactions

  • Potassium + ACE inhibitors/ARBs/spironolactone: ↑ risk of hyperkalemia

  • Calcium + Tetracyclines/fluoroquinolones: ↓ antibiotic absorption

  • Magnesium + CNS depressants: ↑ sedation

  • Iron + Levothyroxine: ↓ absorption of both

  • Zinc + Chelating agents (penicillamine): ↓ efficacy of both

  • Phosphate binders + calcium: risk of calcium-phosphate precipitation

Pharmacokinetics

  • Absorption of oral minerals is influenced by stomach pH, dietary intake, and presence of chelators

  • Distribution is generally wide but compartmentalized (e.g., magnesium stored in bone and soft tissues)

  • Metabolism is not applicable to most, as they are elemental

  • Excretion mainly via kidneys (except iron, which is conserved unless lost via bleeding)

  • Bioavailability: Iron and calcium salts vary by formulation (e.g., ferrous fumarate has higher elemental iron content than gluconate)

Monitoring Parameters

  • Electrolyte Panels: Na⁺, K⁺, Cl⁻, CO₂, Mg²⁺, Ca²⁺, PO₄³⁻

  • Renal function (eGFR, CrCl) prior to administering renally excreted minerals

  • ECG during high-dose potassium or magnesium infusion

  • CBC and ferritin for iron status

  • Serum zinc, copper, selenium levels in parenteral nutrition patients

Warnings and Precautions

  • Potassium IV must be diluted and administered slowly to avoid cardiac arrest

  • Calcium chloride IV is more irritating than calcium gluconate; use central line

  • Magnesium can cause neuromuscular blockade in overdose

  • Iron products can cause anaphylaxis when given IV (e.g., iron dextran)

  • Trace elements should be used with care in hepatic and renal impairment due to accumulation risk

Special Considerations

  • Pregnancy: Most minerals are safe; iron, calcium, and folic acid are essential supplements

  • Pediatrics: Doses must be adjusted by weight; iron overdose is a leading cause of poisoning in children

  • Elderly: Increased risk of constipation from iron and calcium; monitor renal function for magnesium and potassium

Clinical Application in Parenteral Nutrition (TPN)

In patients requiring TPN, minerals and trace elements are included in standardized concentrations:

  • Sodium and potassium as chloride, acetate, phosphate salts

  • Magnesium sulfate

  • Calcium gluconate

  • Phosphate (sodium or potassium salt)

  • Trace elements (zinc, copper, manganese, selenium, chromium)

Dosing in TPN is carefully adjusted to avoid precipitation (e.g., calcium-phosphate compatibility) and accumulation in organ dysfunction.

Examples of Brand and Generic Products

Sodium Chloride:

  • Normal Saline (0.9% NaCl)

  • Hypertonic saline (3% NaCl)

Potassium Chloride:

  • K-Dur, Klor-Con, Slow-K

Calcium Salts:

  • Calcium carbonate (Tums, Caltrate)

  • Calcium gluconate, calcium chloride (IV)

Magnesium:

  • Mag-Ox, magnesium sulfate injection

Phosphate:

  • Fleet Phospho-Soda, K-Phos Neutral

Iron Supplements:

  • Ferrous sulfate (Feosol)

  • Iron sucrose (Venofer), Ferric carboxymaltose (Injectafer)

Zinc:

  • Zinc sulfate tablets

  • Zinc oxide cream (Desitin)

Selenium:

  • Sodium selenite IV or capsule form

Chromium:

  • Chromium picolinate



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