Pentoxifylline
Benjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.
More about the experts All content is checked by medical journalists.The active ingredient pentoxifylline is used as a so-called rheological agent to improve blood circulation. As a xanthine derivative, it is related to caffeine, the stimulating active ingredient in coffee. By improving the flow properties of the blood, pentoxifylline also helps normalize blood clotting. Here you can read everything you need to know about pentoxifylline: effect, use and side effects.
This is how pentoxifylline works
The effect of pentoxifylline is explained by two complementary effects of the active ingredient.
Effect on blood vessels
After ingestion, pentoxifylline reaches the muscle layer in the walls of the blood vessels via the blood. There the active ingredient inhibits the breakdown of the body's own messenger substance cAMP (cyclic adenosine monophosphate). This means that the vessel walls have a lower tension (tone), that is, they are wider. As a result, more blood flows, especially in the very small vessels in the body. In the case of vascular occlusive diseases, pentoxifylline often improves blood flow to the affected extremity.
Effect on red blood cells
Pentoxifylline acts directly on red blood cells (erythrocytes). These are the most common blood cells in terms of numbers and are characterized by the fact that they have a cell nucleus and are biconcave in shape. Thanks to their malleability, they can move through very narrow blood capillaries, even if they are smaller in diameter than normal erythrocytes. Pentoxifylline promotes this deformability.
Other effects
Pentoxifylline also acts on the cells of the immune system in the blood (leukocytes) and on the platelets (thrombocytes). As a result, it has a dampening effect on the immune system, anti-inflammatory and anticoagulant.
Absorption, degradation and excretion of pentoxifylline
After ingestion, pentoxifylline is quickly and completely absorbed in the intestine, but about three-quarters of it is converted in the liver before it enters the body's circulatory system. However, the most common conversion product shows the same effects as pentoxifylline. The highest blood levels are measured about an hour after ingestion. After one and a half hours, around half of the active ingredient and its breakdown products are excreted in the urine via the kidneys.
When is pentoxifylline used?
In Germany, the active ingredient pentoxifylline is only approved for the treatment of peripheral arterial circulatory disorders and circulatory-related disorders of the inner ear. The former often occur as a result of a blood clot in the leg arteries and can lead to so-called "intermittent claudication" due to the reduced resilience: those affected have to keep standing because of leg pain while walking. The inner ear dysfunction can lead to sudden hearing loss and tinnitus.
Outside the approval areas (“off-label”), pentoxifylline is also used to treat other diseases. These include so-called multi-infarct dementia, diseases of the peripheral nerves (peripheral neuropathies), fatty liver and endometriosis.
The duration of use depends on the type and severity of the disease and is determined individually by the doctor.
This is how pentoxifylline is used
The rheological agent pentoxifylline can be fed directly into a vein as an infusion solution or taken in the form of prolonged-release tablets (tablets with delayed release of active substances). The total daily dose is usually between 300 and 1200 milligrams of pentoxifylline. It should be divided into two to three doses, each taken after a meal. The infusion can be done independently of meals. The usual tablet dosages for pentoxifylline are 400 or 600 milligrams per prolonged-release tablet.
It may be useful to take other anticoagulants or active ingredients that promote blood circulation.
What side effects does pentoxifylline have?
Very often, i.e. in more than one in ten patients, adverse drug reactions (ADRs) such as nausea, vomiting, bloating and diarrhea occur.
Common pentoxifylline side effects include flushing (flushing of the face with a sensation of heat), dizziness, tremors, headache and fever.
Allergic reactions occur very rarely. Shortness of breath, swelling of the mucous membranes and low blood pressure occur shortly after ingestion. The active ingredient must then be discontinued immediately and a doctor notified.
What should be considered when using pentoxifylline?
Medicines in particular that have an anticoagulant or antihypertensive effect, such as pentoxifylline, can have an increased effect when taken at the same time. This can lead to an increased drop in blood pressure with dizziness and weakness as well as an increased tendency to bleed. Blood pressure and coagulation values should therefore be checked regularly, especially at the start of combined treatment with pentoxifylline.
When treating diabetes mellitus or prediabetes (an early form of diabetes), care must be taken to ensure that pentoxifylline can also lower blood sugar. This can lead to hypoglycaemia more quickly.
The chemically related theophylline is often used to treat asthma. When used at the same time, theophylline may be reduced less, causing it to accumulate in the body. This can be dangerous, as even a slight overdose of theophylline can cause serious side effects. If theophylline and pentoxifylline are used at the same time, the theophylline dosage may therefore have to be reduced by the attending physician.
Pentoxifylline must not be taken during pregnancy due to a lack of data. The active ingredient is only excreted in breast milk in small amounts during breastfeeding, which is why it can be taken after a careful risk-benefit assessment by the doctor.
There are no data available for use in children and adolescents, which is why its use is not recommended. A dose reduction may be necessary in elderly patients (over 65 years of age) and patients with impaired liver or kidney function.
How to get medication with pentoxifylline
Because of the possible serious side effects, pentoxifylline can only be bought at the pharmacy after a doctor's prescription (i.e. with a prescription).
How long has pentoxifylline been known?
The chemically closely related active ingredient theophylline was extracted from tea leaves by the German biologist Albrecht Kossel in 1888 and then described. However, the further development of the substance to pentoxifylline takes some time. By modifying theophylline, it was possible to achieve that the substance has a more selective effect on the flow properties of the blood. Pentoxifylline was approved in the USA in 1984 and in Germany in 1985. Since the patent protection has already expired, there are numerous generics with the active ingredient pentoxifylline on the market.
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