HYDROFLUMETHIAZIDE

Absorption

Hydroflumethiazide is incompletely but fairly rapidly absorbed from the gastrointestinal tract

Toxicity

Overdoses lead to diuresis, lethargy progressing to coma, with minimal cardiorespiratory depression and with or without significant serum electrolyte changes or dehydration.

Chemical properties

White Solid

Originator

Saluron,Bristol,US,1959

The Uses of HYDROFLUMETHIAZIDE

Labelled Hydroflumethiazide. Antihypertensive; diuretic.

Indications

Used as adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy. Also used in the management of hypertension either as the sole therapeutic agent or to enhance the effect of other antihypertensive drugs in the more severe forms of hypertension.

What are the applications of Application

Hydroflumethiazide is an anti-hypertensive and a diuretic

Background

A thiazide diuretic with actions and uses similar to those of hydrochlorothiazide. (From Martindale, The Extra Pharmacopoeia, 30th ed, p822)

Definition

ChEBI: Hydroflumethiazide is a benzothiadiazine consisting of a 3,4-dihydro-HH-1,2,4-benzothiadiazine bicyclic system dioxygenated on sulfur and carrying trifluoromethyl and aminosulfonyl groups at positions 6 and 7 respectively. A diuretic with actions and uses similar to those of hydrochlorothiazide. It has a role as a diuretic and an antihypertensive agent. It is a benzothiadiazine and a thiazide.

Manufacturing Process

(a) Preparation of 5-Trifluoromethylaniline-2,4-Disulfonyl Chloride: 113 ml of chlorosulfonic acid was cooled in an ice-bath, and to the acid was added dropwise while stirring 26.6 grams of α,α,α-trifluoro-m-toluidine. 105 grams of sodium chloride was added during 1 to 2 hours, whereafter the temperature of the reaction mixture was raised slowly to 150° to 160°C, which temperature was maintained for 3 hours. After cooling the mixture, ice-cooled water was added, whereby 5-trifluoromethylaniline-2,4-disulfonyl chloride separated out from the mixture.
(b) Preparation of 5-Trifluoromethyl-2,4-Disulfamylaniline: The 5- trifluoromethylaniline-2,4-disulfonyl chloride obtained in step (a) was taken up in ether and the ether solution dried with magnesium sulfate. The ether was removed from the solution by distillation, the residue was cooled to 0°C and 60 ml of ice-cooled, concentrated ammonia water was added while stirring. The solution was then heated for one hour on a steam bath and evaporated in vacuo to crystallization. The crystallized product was 5-trifluoromethyl-2,4- disulfamylaniline, which was filtered off, washed with water and dried in a vacuum exsiccator over phosphorus pentoxide. After recrystallization from a mixture of 30% ethanol and 70% water the compound had a MP of 247° to 248°C.
(e) Preparation of 6-Trifluoromethyl-7-Sulfamyl-3,4-Dihydro-1,2,4- Benzothiadiazine-1,1-Dioxide: 3.2 grams of 5-trifluoromethyl-2,4- disulfamylaniline was added to a solution of 0.33 gram of paraformaldehyde in 25 ml of methyl Cellosolve (2-methoxy ethanol) together with a catalytic amount of p-toluenesulfonic acid, and the mixture was boiled with reflux for 5 hours. The solvent was then distilled off in vacuo, and the residue triturated with 30 ml of ethyl acetate. 6-trifluoromethyl-7-sulfamyl-3,4-dihydro-1,2,4- benzothiadiazine-1,1-dioxide crystallized out. After recrystallization from methanol/water the substance had a MP of 272° to 273°C.

Therapeutic Function

Diuretic, Antihypertensive

Pharmacokinetics

Hydroflumethiazide is an oral thiazide used to treat hypertension and edema. High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. Like other thiazides, Hydroflumethiazide promotes water loss from the body (diuretics). Thiazides inhibit Na+/Cl- reabsorption from the distal convoluted tubules in the kidneys. Thiazides also cause loss of potassium and an increase in serum uric acid. Thiazides are often used to treat hypertension, but their hypotensive effects are not necessarily due to their diuretic activity. Thiazides have been shown to prevent hypertension-related morbidity and mortality although the mechanism is not fully understood. Thiazides cause vasodilation by activating calcium-activated potassium channels (large conductance) in vascular smooth muscles and inhibiting various carbonic anhydrases in vascular tissue.

Metabolism

Essentially unchanged