This results in the newly formed dopamine being unable to cross the blood–brain barrier and the effectiveness of L-Dopa treatments is greatly decreased. Carbidopa reduces the amount of levodopa required to produce a given response by about 75% and, when administered with levodopa, increases both plasma levels and the plasma half-life of levodopa, and decreases plasma and urinary dopamine and homovanillic acid. Elimination half-life of levodopa in the presence of carbidopa is about 1.5 hours. Following SINEMET CR, the apparent half-life of levodopa may be prolonged because of continuous absorption. This is extremely useful in the treatment of Parkinsons disease symptoms because the amount of levodopa administered to the patient can be greatly reduced. This reduction in dosage is extremely useful due to the side effects that may occur from an overdose of L-Dopa within the body. Carbidopa is also used in combination with 5-HTP, a naturally occurring amino acid which is a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. carbidopa, which is used in PD to prevent conversion of the levodopa to dopamine, prevents 5-Hydroxytryptophan’s (5-HTP) metabolism in the liver and causes decreased levels of serotonin
in the blood. Research shows that co-administration of 5-HTP and carbidopa greatly increases plasma 5-HTP levels. Several cases of scleroderma-like illness have been reported in patients using carbidopa and 5-HTP. In Europe, 5-HTP is prescribed with carbidopa to prevent the conversion of 5-HTP into serotonin until it reaches the brain.
Allergen immunotherapy, also known as desensitization or hypo-sensitization, is a medical treatment for environmental allergies, such as insect bites, and asthma. Immunotherapy involves exposing people to larger and larger amounts of allergen in an attempt to change the immune systems response.Meta-analyses have found that injections of allergens under the skin are effective in the treatment in allergic rhinitis in children and in asthma. The benefits may last for years after treatment is stopped. It is generally safe and effective for allergic rhinitis, allergic conjunctivitis, allergic forms of asthma, and stinging insects. The evidence also supports the use of sublingual immunotherapy against rhinitis and asthma, but it is less strong. In this form the allergen is given under the tongue and people often prefer it to injections. Immunotherapy is not recommended as a stand-alone treatment for asthma.Side effects during sublingual immunotherapy treatment are usually local and mild and can often be eliminated by adjusting the dosage. Anaphylaxis during sublingual immunotherapy treatment has occurred on rare occasions.Potential side effects related to subcutaneous immunotherapy treatment for asthma and allergic rhinoconjunctivitis include mild or moderate skin or respiratory reactions. Severe side effects such as anaphylaxis during subcutaneous immunotherapy treatment are relatively uncommon.Discovered by Leonard Noon and John Freeman in 1911, allergen immunotherapy is the only medicine known to tackle not only the symptoms but also the causes of respiratory allergies. A detailed diagnosis is necessary to identify the allergens involved.