What is methyldopa?
The substance methyldopa appears at room temperature as a crystalline, solid substance, which has virtually no color. The melting point of methyldopa is about 305 to 307 degrees Celsius. The substance dissolves in dilute mineral acids, but it has only a low solubility in water. In the majority of organic solvents methyldopa is not soluble.
The active ingredient methyldopa is one of the most widely sold drugs for lowering high blood pressure in pregnant women.
Basically, only the L-form is responsible for the pharmacological effects of methyldopa. This means that the substance is levorotatory in its construction. First and foremost, the drug displaces sympathetic neurotransmitters, attacking the biosynthesis of epinephrine and norepinephrine.
Since methyldopa is an amino acid, the substance crosses the blood-brain barrier and enters the brain in this way. There, the active ingredient is converted in the first step in alpha-methyldopamine and finally in alpha-methylnoradrenaline. Further processes lead to the production of norepinephrine being inhibited. Under normal circumstances, norepinephrine causes blood vessels to contract and blood pressure to rise.
After taking the drug Methyldopa, the effect sets in about three to six hours later. The duration of action is 10 to 16 hours. At the beginning of the therapy, the blood pressure drops primarily because the cardiac output decreases. With long-term treatment with methyldopa, the resistance in the vessels decreases, which reduces the blood pressure.
In the majority of cases, the administration of the active ingredient methyldopa takes place orally in the form of tablets. The bioavailability is about 25 percent. The plasma half-life is about one and a half to two hours. However, the blood pressure is lowered over a period of about 10 to 16 hours.
In the small intestine, about 50 percent of the drug is absorbed. From there, they pass into the blood and are transported to the brain. Finally, the drug methyldopa is broken down in the liver and intestine. Finally, the substance remains methyldopa-O-sulfate, which is mainly excreted renally via the urine.
Medical application & use
The active ingredient methyldopa is characterized by several potential applications. First and foremost, methyldopa is a drug used to treat hypertension.
The peculiarity of Methyldopa is that there are a variety of studies regarding the use of the drug during pregnancy. For this reason, the drug is very commonly used to treat high blood pressure in pregnant women. A similar drug forms the drug dihydralazine, which is also used in hypertension during pregnancy or eclampsia.
Methyldopa acts primarily by impairing the action of the central sympathetic nervous system. For this reason, the drug methyldopa is counted among the so-called antisympathotonics.
Risks & Side Effects
Methyldopa is characterized by several potential complaints and unwanted side effects. These vary depending on the individual case and differ in their appearance and severity. Basically, the active ingredient tends to be poorly tolerated by many patients. This should be taken into account in particular when taking the medicine during pregnancy. Although there are numerous studies on the use of the drug in pregnancy, various side effects are possible.
The relatively poor compatibility results primarily from the fact that methyldopa is an antisympathotonicum. A common side effect of this is fatigue, which manifests itself in more than ten percent of all patients treated. This side effect is usually reduced during the treatment.
In addition, dry mucous membranes in the nose and indigestion are possible. In addition, in some patients, the urine turns dark when it comes in contact with air. However, this side effect is harmless. Partly a sedation shows, which only subsides after a few days.
Other potential side effects that sometimes occur during treatment with methyldopa include daytime sleepiness, bradycardia and hypotension. The orthostatic reaction may be disturbed and tremor or hemolysis (including hemolytic anemia) may occur. In addition, dizziness, depression and edema are possible. Some patients also suffer from shortness of breath, fever or so-called extrapyramidal complaints.
In principle, all the difficulties and undesirable side effects that occur during the treatment with the drug methyldopa give rise to the consultation of a doctor. Pregnant women in particular are encouraged to take any side effects seriously. Because in pregnancy, side effects may lead to serious complications that endanger the health or even the life of the unborn child. In such cases a doctor should be consulted immediately. It may be necessary to discontinue methyldopa and to look for an alternative therapy or a better tolerated drug.