BMA Concise Guide to Medicine & Drugs

Bendroflumethiazide (Bendrofluazide)

Brand name Aprinox

Used in the following combined preparation Prestim

QUICK REFERENCE

Drug group Thiazide diuretic

Overdose danger rating Low

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Bendroflumethiazide belongs to the thiazide diuretic group of drugs, which increase the amount of salt and water the kidneys remove from the body. It is used predominantly for treating high blood pressure (see Antihypertensive drugs). The drug may also be used for reducing oedema (water retention) caused by heart, kidney, or liver conditions, and for treating premenstrual oedema. As with all thiazides, this drug increases the loss of potassium in the urine, which can cause various symptoms, and increases the likelihood of irregular heart rhythms, particularly if taken with digoxin for heart failure. Although this effect is rare with low doses, potassium supplements may be given with bendroflumethiazide as a precaution.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Once daily, early in the day. (Sometimes 1–3 x per week.)

Adult dosage range 2.5–10g daily.

Onset of effect Within 2 hours but takes weeks to produce maximum effect on blood pressure.

Duration of action 6–18 hours.

Diet advice Use of this drug may reduce potassium in the body, so you should eat plenty of fresh fruit and vegetables. Discuss with your doctor the advisability of reducing salt intake as a further precaution for hypertension.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose No cause for concern, but take as soon as you remember. However, if it is late in the day do not take the missed dose, or you may need to get up during the night to pass urine. Take the next scheduled dose as usual.

Stopping the drug Do not stop taking the drug without consulting your doctor; symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.

POSSIBLE ADVERSE EFFECTS

Some adverse effects, such as dizziness, nausea, fatigue, and leg cramps, are the result of excessive loss of potassium but can usually be corrected by taking potassium supplements. Bendroflumethiazide may precipitate gout in susceptible people, and diabetes may be more difficult to control. The blood cholesterol level may also rise slightly, and erectile dysfunction (impotence) may occur. Rarely, a rash may develop; if so, you should stop taking the drug and contact your doctor.

INTERACTIONS

Non-steroidal anti-inflammatory drugs (NSAIDs)

may reduce diuretic and antihypertensive effect of bendroflumethiazide, and bendroflumethiazide may increase kidney toxicity of NSAIDs.

Digoxin The effects of digoxin may be increased if excessive potassium is lost.

Anti-arrhythmic drugs Low potassium levels may increase these drugs’ toxicity.

Lithium Bendroflumethiazide may increase lithium levels in the blood.

Corticosteroids These drugs further increase potassium loss when they are taken with bendroflumethiazide. Potassium supplements may be necessary. Corticosteroids may also reduce the diuretic effect of bendroflumethiazide.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have long-term liver or kidney problems.

· You have or have had gout.

· You have diabetes.

· You have Addison’s disease.

· You have hyperparathyroidism.

· You have lactose intolerance.

· You are taking other medicines.

Pregnancy Not usually prescribed. Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk but the amount absorbed by the baby is usually too small to be harmful. Discuss with your doctor.

Infants and children Not usually prescribed. Reduced dose necessary.

Over 60 Reduced dose may be necessary.

Driving and hazardous work No special problems.

Alcohol No problems expected if consumption is kept low.

PROLONGED USE

Prolonged use of this drug can lead to excessive loss of potassium and imbalances of other salts.

Monitoring Blood tests may be performed periodically to check kidney function and levels of potassium and other salts.