Brand Name: HYDROPIL
Generic Name: Hydrochlorothiazide
Preparations: 12.5/ 25 mg Tablets
Pharmacological Category: Thiazide diuretic

Mechanism of Action (MOA)
HYDROPIL (Hydrochlorothiazide) inhibits the sodium-chloride symporter in the distal convoluted tubule, which is responsible for 5% of total sodium reabsorption thereby inhibiting reabsorption of sodium along with water.

Pharmacokinetics
Absorption: Fairly rapidly absorbed from the gastrointestinal tract
Onset of Action: Diuresis: nearly 2 hour; in hypertension: 3-4 days
Peak Effect: Diuresis: 4-6 hours
Bioavailability: About 65 to 70%
Plasma Half-life: About 5 and 15 hours
Protein Binding: 40-68%
Distribution: Crosses the placental barrier and distributed into breast milk
Metabolism: Minimally metabolized
Elimination Half-life: 5.6-14.8 hours
Excretion: Mainly unchanged in the urine

Indications and Dosage
• Hypertension: Initially 12.5 mg daily followed by 25 to 50 mg daily if necessary, either alone or with other antihypertensives. Maximum dose: 100 mg daily.
• Oedema associated with heart failure/ renal & hepatic disorders, premenstrual syndrome, corticosteroids and oestrogens: Usual dose is 25 to 100 mg daily, may be reduced to a dose of 25 to 50 mg daily or intermittently. In severe cases: Initial doses of up to 200 mg daily, but the more powerful loop diuretics are preferred in such patients.
• Nephrogenic diabetes insipidus:
Adult: Initial dose of up to 100 mg daily
Children: 1 to 2 mg/kg daily in single or 2 divided doses
Infants under 6 months: doses of up to 3 mg/kg daily

Administration: usually given in the morning so that sleep is not interrupted by diuresis.

Side Effects
COMMON: Nausea, vomiting, loss of appetite, diarrhoea, constipation, muscle spasm, dizziness, headache
(Signs of electrolyte imbalance include dry mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pain and cramps, seizures, oliguria, hypotension, and gastrointestinal disturbances.)
OTHER: Anorexia, Sialadenitis, photosensitivity reactions, orthostatic hypotension, paraesthesia, impotence, and yellow vision
REPORTED: Hypersensitivity reactions include skin rashes, fever, pulmonary oedema, pneumonitis, anaphylaxis, and toxic epidermal necrolysis. cholestatic jaundice, pancreatitis, and blood dyscrasias including thrombocytopenia
RARE: Granulocytopenia, leucopenia, and aplastic and haemolytic anaemia

Contraindications
Severe hepatic/ renal impairment, anuria, hypercalcaemia, Addison’s disease

Warnings/ Precautions
• Caution in elderly and patients with existing fluid and electrolyte disturbances.
• May cause hyperuricaemia and precipitate attacks of gout in some patients.
• May be associated with electrolyte imbalances including hypochloraemic alkalosis, hyponatraemia, and hypokalaemia.
• Hypokalaemia intensifies the effect of digitalis on cardiac muscle and treatment with digitalis or its glycosides may have to be temporarily suspended.
• Patients with hepatic cirrhosis are particularly at risk from hypokalaemia.
• May cause hyperglycaemia and aggravate or unmask diabetes mellitus. Blood-glucose concentrations should be monitored in patients taking antidiabetics, since requirements may change.
• Can reduce urinary excretion of calcium, sometimes resulting in mild hypercalcaemia.

Drug Interactions
• Concomitant use of digoxin with hydrochlorothiazide may increase the toxicity of digoxin by hypokalaemic effect.
• May increase the risk of arrhythmias with drugs that prolong the QT interval.
• May enhance the effect of other antihypertensives, particularly the first-dose hypotension that occurs with alpha blockers or ACE inhibitors.
• Orthostatic hypotension associated with diuretics may be enhanced by alcohol, barbiturates, or opioids.
• The antihypertensive effects may be antagonised by drugs that cause fluid retention, such as corticosteroids, NSAIDs, or carbenoxolone; diuretics may enhance the nephrotoxicity of NSAIDs.
• Should not usually be used with lithium because of lithium toxicity. Other drugs for which increased toxicity has been reported when given with thiazides include allopurinol and tetracyclines.
• May alter the requirements for hypoglycaemics in diabetic patients.

Pregnancy Category: B

Presentations
HYDROPIL 12.5: 10 X 10’s
HYDROPIL 25: 10 X 10’s