Wytens (ANTIHYPERTENSIVES_DIURETICS)

Uses

Bisoprolol plus Hydrochlorothiazide is used for the treatment of Hypertension.

Wytens (ANTIHYPERTENSIVES_DIURETICS) is also used to associated treatment for these conditions: Atrial Fibrillation, Cardiovascular Events, Chronic Stable Angina Pectoris, Heart Failure, High Blood Pressure (Hypertension), Mild Hypertension, Premature Ventricular Contraction (PVC), Supraventricular Arrhythmias, Moderate Hypertension, Perioperative arrhythmiaAcidosis, Renal Tubular, Calcium Nephrolithiasis, Cirrhosis of the Liver, Congestive Heart Failure (CHF), Diabetes Insipidus, Edema, High Blood Pressure (Hypertension), Hypertension,Essential, Hypokalemia caused by diuretics, Nephrotic Syndrome, Premenstrual tension with edema, Sodium retention, Stroke, Prophylaxis of preeclampsia

How Wytens (ANTIHYPERTENSIVES_DIURETICS) works

Though the mechanism of action of bisoprolol has not been fully elucidated in hypertension, it is thought that therapeutic effects are achieved through the antagonism of β-1adrenoceptors to result in lower cardiac output. Bisoprolol is a competitive, cardioselective β1-adrenergic antagonist. When β1-receptors (located mainly in the heart) are activated by adrenergic neurotransmitters such as epinephrine, both the blood pressure and heart rate increase, leading to greater cardiovascular work, increasing the demand for oxygen. Bisoprolol reduces cardiac workload by decreasing contractility and the need for oxygen through competitive inhibition of β1-adrenergic receptors.

Bisoprolol is also thought to reduce the output of renin in the kidneys, which normally increases blood pressure. Additionally, some central nervous system effects of bisoprolol may include diminishing sympathetic nervous system output from the brain, decreasing blood pressure and heart rate.

Hydrochlorothiazide is transported from the circulation into epithelial cells of the distal convoluted tubule by the organic anion transporters OAT1, OAT3, and OAT4. From these cells, hydrochlorothiazide is transported to the lumen of the tubule by multidrug resistance associated protein 4 (MRP4).

Normally, sodium is reabsorbed into epithelial cells of the distal convoluted tubule and pumped into the basolateral interstitium by a sodium-potassium ATPase, creating a concentration gradient between the epithelial cell and the distal convoluted tubule that promotes the reabsorption of water.

Hydrochlorothiazide acts on the proximal region of the distal convoluted tubule, inhibiting reabsorption by the sodium-chloride symporter, also known as Solute Carrier Family 12 Member 3 (SLC12A3). Inhibition of SLC12A3 reduces the magnitude of the concentration gradient between the epithelial cell and distal convoluted tubule, reducing the reabsorption of water.

Dosage

Wytens (ANTIHYPERTENSIVES_DIURETICS) dosage

Bisoprolol is an effective treatment of hypertension in once-daily doses of 2.5 mg to 40 mg, while hydrochlorothiazide is effective in doses of 12.5 mg to 50 mg. In clinical trials of bisoprolol/hydrochlorothiazide combination therapy using bisoprolol doses of 2.5 mg to 20 mg and hydrochlorothiazide doses of 6.25 mg to 25 mg.

Side Effects

Generally well tolerated. Most side effects have been mild and transient. Normally fatigue, dizziness, headache, bradycardia, arrhythmia, peripheral ischemia, chest pain, palpitations, rhythm disturbances, cold extremities, claudication, orthostatic hypotension, diarrhoea, constipation, nausea, dyspepsia, rhinitis, pharyngitis etc. may occur.

Toxicity

LD50 information Oral LD50 of bisoprolol in the mouse was 730 mg/kg.

Overdose information

Signs of a β-blocker overdose include cardiovascular symptoms such as hypotension, congestive heart failure, and bradycardia. Other symptoms such as bronchospasm, and hypoglycemia may occur. If an overdose occurs with bisoprolol, supportive treatment should be initiated. Glucagon has been shown to be beneficial in bradycardia and hypotension associated with beta-blocker overdosage. Hypoglycemia may be managed by administering IV glucose. Monitor the patient and administer atropine in cases of bradycardia, pressors and fluids in the case of hypotension, and conventional heart failure therapy if heart failure occurs. If heart block occurs, the patient must be closely monitored and isoproterenol infusion or transvenous cardiac pacemaker insertion should take place. For the management of overdose-related bronchospasm, administer bronchodilators with or without IV aminophylline. Limited research suggests that bisoprolol fumarate is not removed adequately by hemodialysis sessions.

The oral LD₅₀ of hydrochlorothiazide is >10g/kg in mice and rats.

Patients experiencing an overdose may present with hypokalemia, hypochloremia, and hyponatremia. Treat patients with symptomatic and supportive treatment including fluids and electrolytes. Vasopressors may be administered to treat hypotension and oxygen may be given for respiratory impairment.

Precaution

Dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances are potential syndrome of fluid and electrolyte imbalance.Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction rather than salt administration.Hyperuricemia or acute gout may be precipitated in certain patients receiving thiazide diuretics. Bisoprolol fumarate, alone or in combination with hydrochlorothiazide, has been associated with increases in uric acid.

Interaction

Bisoprolol should not be combined with other beta-blocking agents. Patients receiving catecholamine-depleting drugs should be closely monitored, because the added beta-adrenergic blocking action of Bisoprolol may produce excessive reduction of sympathetic activity. In patients receiving concurrent therapy with clonidine, if therapy is to be discontinued, it is suggested that Bisoprolol be discontinued for several days before the withdrawal of clonidine. Bisoprolol should be used with care when myocardial depressants or inhibitors of AV conduction, such as certain calcium antagonists or antiarrhythmic agents are used concurrently. Concomitant use with digitalis glycosides can increase the risk of bradycardia. Concurrent use of rifampin increases the metabolic clearance of Bisoprolol, resulting in a shortened elimination half-life of Bisoprolol. However, initial dose modification is generally not necessary.

Volume of Distribution

The volume of distribution of bisoprolol is 3.5 L/kg. The mean volume of distribution was found to be 230 L/kg in heart failure patients, which was similar to the volume of distribution in healthy patients. Bisoprolol is known to cross the placenta.

The volume of distribution varies widely from one study to another with values of 0.83-4.19L/kg.

Elimination Route

Bisoprolol is well absorbed in the gastrointestinal tract. The AUC is 642.87 g.hr/mL and bioavailability of bisoprolol is about 90% due to the minimal first pass effects. Absorption is unaffected by food intake. Peak plasma concentrations of bisoprolol are attained within 2-4 hours and steady-state concentrations are achieved within 5 days of administration. In a pharmacokinetic study, the mean peak concentration of bisoprolol was 52 micrograms/L. Cmax at steady state concentrations of bisoprolol is 64±21 ng/ml administered at 10 mg daily.

An oral dose of hydrochlorothiazide is 65-75% bioavailable, with a T_max of 1-5 hours, and a C_max of 70-490ng/mL following doses of 12.5-100mg. When taken with a meal, bioavailability is 10% lower, C_max is 20% lower, and T_max increases from 1.6 to 2.9 hours.

Half Life

A pharmacokinetic study in 12 healthy individuals determined the mean plasma half-life of bisoprolol to be 10-12 hours. Another study comprised of healthy patients determined the elimination half-life to be approximately 10 hours. Renal impairment increased the half-life to 18.5 hours.

The plasma half life of hydrochlorothiazide is 5.6-14.8h.

Clearance

Total body clearance in healthy patients was determined to be 14.2 L/h. In patients with renal impairment, clearance was reduced to 7.8 L/h. Hepatic dysfunction also reduced the clearance of bisoprolol.

The renal clearance of hydrochlorothiazide in patients with normal renal function is 285mL/min. Patients with a creatinine clearance of 31-80mL/min have an average hydroxychlorothiazide renal clearance of 75mL/min, and patients with a creatinine clearance of ≤30mL/min have an average hydroxychlorothiazide renal clearance of 17mL/min.

Elimination Route

Bisoprolol is eliminated equally by both renal and hepatic pathways. About 50% of an oral dose is excreted unchanged in the urine with the remainder of the dose excreted as inactive bisoprolol metabolites. Under 2% of the ingested dose is found to be excreted in the feces.

Hydrochlorothiazide is eliminated in the urine as unchanged hydrochlorothiazide.

Pregnancy & Breastfeeding use

Use in special population:

Nursing Mothers: Thiazides are excreted in human breast milk. Small amounts of bisoprolol fumarate (< 2% of the dose) have been detected in the milk of lactating rats. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Use in Pregnancy: Pregnancy Category C.

Geriatric Use: No overall differences in effectiveness or safety were observed between these patients and younger patients. Other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Contraindication

It is contraindicated in patients in cardiogenic shock, overt cardiac failure, second or third degree AV block, marked sinus bradycardia, anuria and hypersensitivity to either component of this product or to other sulfonamide derived drugs.

Special Warning

Pediatric Patients: There is no pediatric experience with Bisoprolol.

Geriatric Patients: It is not necessary to adjust the dose in the elderly, unless there is also significant renal or hepatic dysfunction.

Renal impairment: Reduce dose if eGFR less than 20 ml/ minute/ 1.73 m2 (max. 10 mg daily).

Hepatic impairment: Maximum 10 mg daily in severe impairment (hepatitis or cirrhosis).

Elderly: in some patients specially the elderly an initial dose of 12.5 mg daily may be sufficient.

Children: An initial dose for children has been 1 to 2 mg per kg body-weight in 2 divided doses. Infants under 6 months may need doses upto 3 mg per kg daily.

Acute Overdose

There are limited data on overdose with bisoprolol fumarate and hydrochlorothiazide. The most frequently observed signs expected with overdosage of a beta-blocker are bradycardia and hypotension. Lethargy is also common, and with severe overdoses, delirium, coma, convulsions, and respiratory arrest have been reported to occur. Congestive heart failure, bronchospasm, and hypoglycemia may occur.

Storage Condition

Store in a cool and dry place, protected from light.

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