Drug information of polythiazide

polythiazide


Polythiazide is a thiazide diuretic. A diuretic is any substance that promotes the production of urine.
A thiazide diuretic with actions and uses similar to those of hydrochlorothiazide. 

Mechanism of effect

The mechanism of action results in an interference with the renal tubular mechanism of electrolyte reabsorption. At maximal therapeutic dosage all thiazides are approximately equal in their diuretic potency. The mechanism whereby thiazides function in the control of hypertension is unknown.

Pharmacodynamic

As a thiazide diuretic, Polythiazide inhibits the sodium-chloride symporter which decreases solute reabsorption leading to a retention of water in the urine, as water normally follows solutes. More frequent urination is due to the increased loss of water that has not been retained from the body as a result of a concomitant relationship with sodium loss from the convoluted tubule. The short-term anti-hypertensive action is based on the fact that thiazides decrease preload, decreasing blood pressure

Drug indications

Renese (polythiazide) is indicated as adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy.
Renese (polythiazide) has also been found useful in edema due to various forms of renal dysfunction as: Nephrotic syndrome; Acute glomerulonephritis; and Chronic renal failure.
Renese (polythiazide) is indicated in the management of hypertension either as the sole therapeutic agent or to enhance the effectiveness of other antihypertensive drugs in the more severe forms of hypertension.

Dosage

The usual dosage of Renese (polythiazide) tablets for diuretic therapy is 1 to 4 mg daily, and for antihypertensive therapy is 2 to 4 mg daily.

Drug contraindications

Anuria. Hypersensitivity to this or other sulfonamide derived drugs.

Side effects

Gastrointestinal System Reactions
  1. anorexia
  2. gastric irritation
  3. nausea
  4. vomiting
  5. cramping
  6. diarrhea
  7. constipation
  8. jaundice (intrahepatic cholestatic jaundice)
  9. pancreatitis
Central Nervous System Reactions
  1. dizziness
  2. vertigo
  3. paresthesias
  4. headache
  5. xanthopsia
Hematologic Reactions
  1. leukopenia
  2. agranulocytosis
  3. thrombocytopenia
  4. aplastic anemia
Dermatologic —Hypersensitivity Reactions
  1. purpura
  2. photosensitivity
  3. rash
  4. urticaria
  5. necrotizing angiitis (vasculitis) (cutaneous vasculitis)
Cardiovascular Reaction
Orthostatic hypotension may occur and may be aggravated by alcohol, barbiturates or narcotics.

Alerts

Thiazides should be used with caution in severe renal disease. In patients with renal disease, thiazides may precipitate azotemia. Cumulative effects of the drug may develop in patients with impaired renal function.
Thiazides should be used with caution in patients with impaired hepatic function or progressive liver disease, since minor alterations of fluid and electrolyte balance may precipitate hepatic coma.
Thiazides may add to or potentiate the action of other antihypertensive drugs. Potentiation occurs with ganglionic or peripheral adrenergic blocking drugs.
Sensitivity reactions may occur in patients with a history of allergy or bronchial asthma.
The possibility of exacerbation or activation of systemic lupus erythematosus has been reported.

Points of recommendation

Periodic determination of serum electrolytes to detect possible electrolyte imbalance should be performed at appropriate intervals.
All patients receiving thiazide therapy should be observed for clinical signs of fluid or electrolyte imbalance; namely, hyponatremia, hypochloremic alkalosis, and hypokalemia. Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids. Medication such as digitalis may also influence serum electrolytes. Warning signs, irrespective of cause, are: dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting.
Hypokalemia may develop with thiazides as with any other potent diuretic, especially with brisk diuresis, when severe cirrhosis is present, or during concomitant use of corticosteroids or ACTH.
Interference with adequate oral electrolyte intake will also contribute to hypokalemia. Digitalis therapy may exaggerate metabolic effects of hypokalemia especially with reference to myocardial activity.
Any chloride deficit is generally mild and usually does not require specific treatment except under extraordinary circumstances (as in liver disease or renal disease). Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction, rather than administration of salt except in rare instances when the hyponatremia is life threatening. In actual salt depletion, appropriate replacement is the therapy of choice.
Hyperuricemia may occur or frank gout may be precipitated in certain patients receiving thiazide therapy.
Insulin requirements in diabetic patients may be increased, decreased, or unchanged. Latent diabetes mellitus may become manifest during thiazide administration.
Thiazide drugs may increase the responsiveness to tubocurarine.
The antihypertensive effects of the drug may be enhanced in the postsympathectomy patient.
Thiazides may decrease arterial responsiveness to norepinephrine. This diminution is not sufficient to preclude effectiveness of the pressor agent for therapeutic use.
If progressive renal impairment becomes evident, as indicated by a rising nonprotein nitrogen or blood urea nitrogen, a careful reappraisal of therapy is necessary with consideration given to withholding or discontinuing diuretic therapy.
Thiazides may decrease serum PBI levels without signs of thyroid disturbance.

Pregnancy level

Polythiazide has been assigned to pregnancy category C by the FDA.

Breast feeding warning

No information is available on the amount of polythiazide in breastmilk. Intense diuresis with large doses may decrease breastmilk production. Other diuretics in low doses are preferred over polythiazide.

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