Chlorphenamine is an antihistamine that is used to treat allergic diseases. It inhibits the action of the neurotransmitter histamine and thus counteracts allergic symptoms such as itching, redness, and skin reactions. Chlorphenamine also has an antidepressant and sedative effect. It is marketed under various trade names as a monopreparation and also as a substance in combination preparations. Possible side effects include fatigue, nervousness, dry mouth, and sleep disturbances.
What is chlorphenamine?
Chlorphenamine belongs to the alkylamine chemical group. It is a first-generation antihistamine. The drug is used in human and veterinary medicine to treat allergic reactions. The drug is known under the trade names Trimeton and Balkis Dr. Henk Schnupfenkapseln. It is also contained in various combination preparations such as Solmucalm, Rhinopront, Pecto-Baby, Migraine-Kranit and Benical. In medical devices, chlorphenamine is present as so-called chlorphenamine maleate. Chlorphenamine maleate is a white, crystalline powder and is soluble in water.
Pharmacological effect
Chlorphenamine is a histamine receptor antagonist. These agents decreased or even completely abolish the effect of histamine, a messenger substance that is intrinsic to the body. Histamine is a biogenic amine and an important mediator in the human body. It plays a role in gastric acid production and in the central nervous system. It is also responsible for allergic reactions. Upon contact with an allergen, histamine is released in granulocytes and the mast cells and binds to the receptor. This can lead to redness, edema and itching. Chlorphenamine acts at the so-called H1 receptor. The H1 receptors are located on endothelial cells. After their activation, there is a release of nitric oxide due to increased calcium levels. This results in relaxation of the vascular musculature. This circumstance leads to so-called vasodilation. The blood vessels dilate. Due to the release of histamine, this process can lead to allergy symptoms such as itching, reddening of the skin or anaphylactic shock. The latter is life-threatening. Chlorphenamine has other properties in addition to its effect on the neurotransmitter histamine. It has an antidepressant effect because it reduces the reuptake of norepinephrine and serotonin at the nerve endings. However, there have been no studies on this possible area of application in humans to date. In addition, chlorphenamine has a fatiguing (sedative) effect.
Medical use and application
Because of its inhibitory action at the histamine receptor, chlorphenamine is used to treat allergic diseases. Therefore, indications include respiratory diseases such as hay fever, rhinitis, allergic rhinitis, chronic runny nose, and sinusitis. In addition, it can be used to treat colds and flu-like effects. The drug can also be used for symptomatic therapy in allergic reactions such as hives or conjunctivitis. Since the drug has an antidepressant effect, it could conceivably be used to treat depressive moods. However, this mode of action has not yet been demonstrated in humans. Due to the relaxing and sedative effect of the medical product, chlorphenamine is not infrequently misused as a sedative. This is particularly dangerous in combination with other depressant substances such as alcohol. The simultaneous use of these substances can intensify the undesirable effects of the drug. In addition to alcohol, an interaction between chlorphenamine maleate and neuroleptics, benzodiazepines or antidepressants is possible. Chlorphenamine should not be used in medicine if the patient suffers from hypersensitivity, bladder emptying disorders or a severely enlarged prostate. Furthermore, the substance should not be used to treat acute asthma attacks. In addition, the drug should not be taken during pregnancy and lactation. Furthermore, young children should not be treated with chlorphenamine.
Risks and side effects
Chlorphenamine has a variety of side effects. Adverse effects include dry mouth, sore throat, nasal dryness, sleep disturbances, fatigue, nervousness, drowsiness, and vision loss. In addition, the drug can cause glaucoma.Since chlorphenamine has a fatiguing effect, people should refrain from operating machinery and driving while taking it. In case of an overdose of the active substance, a so-called anticholinergic syndrome may occur. This is characterized by fever, convulsions, dry mouth, flushing of the skin, and hallucinations. Muscle tension, low blood pressure, circulatory collapse, and respiratory paralysis are other symptoms that can occur with an overdose of the drug. Therefore, a fatal outcome cannot be ruled out if the drug is used incorrectly. A 2015 American cohort study also demonstrated a positive correlation of long-term use of chlorphenamine maleate with an increased risk of dementia diseases such as Alzheimer’s.
