How hydrochlorothiazide works
Hydrochlorothiazide acts directly in the kidneys. There, the entire blood volume is passed through about three hundred times per day. In the process, the so-called primary urine is squeezed out through a filter system (renal corpuscles).
This primary urine still contains the same concentration of salts and small molecules (such as sugar and amino acids) as the blood. It is transported via the renal tubules, where it is concentrated into secondary or final urine, into the renal pelvis, the ureters and finally into the bladder.
Concentration is achieved by reabsorbing water and energy-rich substances (salts, sugars, amino acids) that are still usable by the body in the renal tubules. In this way, the 180 liters of primary urine produced per day by an adult give rise to about two liters of final urine.
This effectively reduces blood volume and the amount of water accumulated in the tissues. This lowers blood pressure, which means the heart has to work less intensively. This relieves the heart as well as the vessels near the heart.
Thiazide diuretics, which include hydrochlorothiazide, have a flat dose-response curve. This means that, unlike loop diuretics (such as furosemide), higher doses are not associated with greater diuresis.
Absorption, degradation and excretion
After ingestion, hydrochlorothiazide is largely absorbed from the intestine into the blood, where about 75 percent is found after two to five hours. It exerts its effect in the renal tubules, which is noticeable about one to two hours after ingestion.
Finally, the active ingredient is excreted through the kidneys in the urine. About six to eight hours after ingestion, half of the active ingredient has left the body.
When is hydrochlorothiazide used?
- High blood pressure (arterial hypertension)
- Water retention in the tissues (edema)
- Heart failure (cardiac insufficiency) for symptomatic therapy
Hydrochlorothiazide is often administered in combination with other active ingredients that have a more targeted effect on the underlying disease (for example, in heart failure together with ACE inhibitors). This increases the blood pressure-lowering effect of hydrochlorothiazide, for example.
In the case of chronic underlying diseases, the diuretic can be used on a long-term basis.
How hydrochlorothiazide is used
Hydrochlorothiazide is usually taken in tablet form, unchewed with food and a glass of water. It is taken once daily in the morning.
The maintenance dosage for high blood pressure is usually between 12.5 and 50 milligrams.
What are the side effects of hydrochlorothiazide?
Frequently (in one in ten to one hundred people treated), side effects include high uric acid levels (hyperuricemia, which can lead to gout attacks in gout patients), high blood sugar levels (hyperglycemia), skin rash with itching, loss of appetite, nausea, vomiting, impotence disorders, and a drop in blood pressure when standing up from a sitting or lying position (orthostatic hypotension) – especially at the beginning of therapy with hydrochlorothiazide.
What should be considered when taking hydrochlorothiazide?
Contraindications
Hydrochlorothiazide must not be used in:
- acute glomerulonephritis (inflammation of the renal corpuscles)
- severe renal dysfunction
- Electrolyte disorders
- @ gout
- dehydration (dehydration or dehydration)
Interactions
Non-steroidal anti-inflammatory drugs (NSAIDs) that are frequently taken as painkillers (such as acetylsalicylic acid = ASA, ibuprofen, naproxen, diclofenac) can weaken the effect of hydrochlorothiazide. The same applies to coxibs (selective COX-2 inhibitors), which also belong to the group of NSAIDs.
Caution is advised with the simultaneous use of active ingredients with a narrow therapeutic range – i.e. active ingredients whose dosage must be precisely adhered to, because overdosage or underdosage occurs rapidly. Such agents include cardiac glycosides such as digitoxin and digoxin, and mood stabilizers such as lithium. When combined with hydrochlorothiazide, blood level monitoring is recommended.
Diabetics should check their blood glucose levels regularly when taking hydrochlorothiazide.
Age Limitation
Hydrochlorothiazide is not approved for use in children and adolescents because there are insufficient data on efficacy and safety in this age group.
Since hydrochlorothiazide can lead to a reduced supply to the placenta and thus to the child in pregnant women, it should not be used during pregnancy. However, if a diuretic is absolutely necessary, the active substance can be used.
Hydrochlorothiazide is acceptable up to a dosage of 50 mg daily during breastfeeding.
How to get medications with hydrochlorothiazide
Medicines containing hydrochlorothiazide are available by prescription and in pharmacies in Germany, Austria, and Switzerland in any dosage, package size, and combination.
How long has hydrochlorothiazide been known?
Hydrochlorothiazide was developed in 1955 by chemist George deStevens and marketed as early as 1958. It was one of the first active ingredients that could effectively and reliably lower blood pressure. In the meantime, numerous combination preparations and generics containing the active ingredient hydrochlorothiazide are available.
