Thyrox Plus

Nicotinamide (25mg) + Thyroxine (15mg) + Vitamin B6 (Pyridoxine) (1mg)
Price: ₹70 - ₹110 for 30 tablets
Mfr: Merck Limited | Form: Tablet

📋 Clinical Overview

A fixed-dose combination product containing a B-vitamin (Nicotinamide), a thyroid hormone (Thyroxine), and another B-vitamin (Pyridoxine). It is primarily indicated for the management of pellagra and associated nutritional deficiencies, often seen in specific at-risk populations in India. The thyroxine component is present in a very low, non-hormone replacement dose, historically posited to have metabolic or dermatological effects, though this use is not supported by modern endocrinology guidelines. The combination is not a standard therapy for hypothyroidism.

💊 Dosage & Administration

Adult: One tablet once daily, or as directed by the physician. Typically taken in the morning on an empty stomach.

Note: Take tablet on an empty stomach, at least 30 minutes before breakfast, with a full glass of water. Do not take with coffee, milk, or antacids. Maintain a consistent daily schedule.

⚠️ Contraindications

  • Hypersensitivity to any component
  • Uncorrected adrenal insufficiency (due to thyroxine component)
  • Thyrotoxicosis
  • Acute myocardial infarction untreated

🔬 Mechanism of Action

Nicotinamide: Precursor to NAD and NADP, essential coenzymes in redox reactions, DNA repair, and cellular energy metabolism. It also inhibits poly(ADP-ribose) polymerase (PARP) and has anti-inflammatory effects on skin. Levothyroxine (at 15mcg): The physiological role of such a micro-dose is unclear; it may provide trace hormone support but is insufficient to treat hypothyroidism. It may have subtle effects on basal metabolic rate. Pyridoxine: Converted to pyridoxal phosphate (PLP), a cofactor for over 140 enzymes involved in amino acid, glucose, and lipid metabolism, neurotransmitter synthesis (serotonin, dopamine, GABA), and heme synthesis.

🤕 Side Effects

  • Nausea
  • Headache
  • Flushing (less common with nicotinamide vs. niacin)
  • Mild gastritis

🤰 Special Populations

Pregnancy: Levothyroxine is Category A; requirements often increase during pregnancy. Nicotinamide and Pyridoxine are generally safe. However, this fixed-dose combination is not a recommended source of levothyroxine for hypothyroidism in pregnancy. Use only if clearly needed and under strict supervision. Pyridoxine is used for nausea in pregnancy at higher doses.

Driving: Usually no effect. However, if symptoms of hyperthyroidism (nervousness, tremor) occur, may impair ability to drive or operate machinery.

🔄 Drug Interactions

Oral Anticoagulants (Warfarin)Levothyroxine may potentiate anticoagulant effect; increased INR risk.Major
Antidiabetic Agents (Insulin, Sulfonylureas)Levothyroxine may reduce glycemic control; adjust dose.Moderate
DigoxinLevothyroxine may decrease serum digoxin levels.Moderate
Antacids (Calcium, Aluminum, Magnesium)Decrease absorption of levothyroxine. Separate by at least 4 hours.Major
Iron SupplementsDecrease absorption of levothyroxine. Separate by at least 4 hours.Major
Proton Pump Inhibitors (Omeprazole)May reduce levothyroxine absorption by altering gastric pH.Moderate
Phenytoin, CarbamazepineIncrease metabolism of levothyroxine, may increase dose requirement.Moderate
IsoniazidMay increase pyridoxine requirements/antagonize effect.Moderate

🔁 Alternatives to Thyrox Plus

Same composition (Nicotinamide (25mg) + Thyroxine (15mg) + Vitamin B6 (Pyridoxine) (1mg)), different brands:

Thyronorm Forte Thyrofit Eltroxin Plus