After oral administration of hydrochlorothiazide, diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to 12 hours.
Hydrochlorothiazide may alter glucose tolerance and raise serum levels of cholesterol and triglycerides.
Hydrochlorothiazide may raise the serum uric acid level due to reduced clearance of uric acid and may cause or exacerbate hyperuricemia and precipitate gout in susceptible patients.
Thiazides decrease urinary calcium excretion and may cause mild elevation of serum calcium. Avoid using benazepril hydrochloride and hydrochlorothiazide in patients with hypercalcemia.
Ion exchange resins
Stagger the dosage of hydrochlorothiazide and ion exchange resins such that hydrochlorothiazide is administered at least 4 hours before or 4 to 6 hours after the administration of resins. Single doses of either cholestyramine or colestipol resins bind the hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by up to 85% and 43%, respectively.
Digitalis Glycosides
Thiazide-induced hypokalemia or hypomagnesemia may predispose the patients to digoxin toxicity.
Skeletal Muscle Relaxants
Possible increased responsiveness to muscle relaxants such as curare derivatives.
Antidiabetic Agents
Dosage adjustment of antidiabetic drug may be required.
Antineoplastic Agents (e.g., cyclophosphamide, methotrexate)
Concomitant use of thiazide diuretics may reduce renal excretion of cytotoxic agents and enhance their myelosuppressive effects.
Drugs that Alter Gastrointestinal Motility
The bioavailability of thiazide-type diuretics may be increased by anticholinergic agents (e.g., atropine, biperiden), apparently due to a decrease in gastrointestinal motility and the stomach emptying rate. Conversely, pro-kinetic drugs may decrease the bioavailability of thiazide diuretics.
Cyclosporin
Concomitant treatment with diuretics may increase the risk of hyperuricaemia and gout-type complications.
Alcohol, Barbiturates or Narcotics
Concomitant administration of thiazide diuretics with alcohol, barbiturates, or narcotics may potentiate orthostatic hypotension.
Pressor Amines
Hydrochlorothiazide may reduce the response to pressor amines such as noradrenaline but the clinical significance of this effect is not sufficient to preclude their use.
Minor alterations of fluid and electrolyte imbalance may precipitate hepatic coma in patients with impaired hepatic function or progressive liver disease.
Digestive
Pancreatitis, small bowel angioedema, jaundice (intrahepatic cholestatic), sialadenitis, vomiting, diarrhea, cramping, nausea, gastric irritation, constipation, and anorexia.
Neurologic
Vertigo, lightheadedness, transient blurred vision, headache, paresthesia, xanthopsia, weakness, and restlessness.
Musculoskeletal
Muscle spasm.
Hematologic
Aplastic anemia, agranulocytosis, leukopenia, neutropenia and thrombocytopenia.
Metabolic
Hyperglycemia, glycosuria, and hyperuricemia, pyrexia, asthenia, parathyroid gland changes with hypercalcemia and hypophosphatemia.
Hypersensitivity
Anaphylactoid reactions, necrotizing angiitis, respiratory distress (including pneumonitis and pulmonary edema), purpura, urticaria, rash, and photosensitivity.
Skin
Erythema multiforme including Stevens-Johnson syndrome, and exfoliative dermatitis including toxic epidermal necrolysis.