Definition
Myasthenia gravis is a chronic autoimmune disease characterized by an "alteration in the transmission of the contractile signals that the nerves send to the muscles.
More specifically, this pathology affects the post-synaptic cholinergic receptors located in the neuromuscular junction.
Causes
Being an autoimmune disease, myasthenia gravis is triggered by an abnormal response of the immune system towards certain parts of the body of the same organism.
In the case of myasthenia gravis, the immune system produces autoantibodies against acetylcholine receptors located in the neuromuscular plaque. More specifically, the antibodies bind to these receptors, blocking them and thus preventing the link with acetylcholine.
In some individuals, moreover, it seems that in the etiology of myasthenia gravis there is also the involvement of the thymus (a gland present in the chest involved in the development of the immune system). However, the exact link between the thymic gland and myasthenia gravis is not still been fully clarified.
Symptoms
The alteration in the transmission of contractile signals - due to the blocking of cholinergic receptors by autoantibodies - reduces the ability of the muscle to contract. All this translates into severe weakness and a great feeling of fatigue during the use of voluntary muscles. .
In some cases, the weakness can be localized only to some muscles, such as the ocular muscles (we therefore speak of ocular myasthenia); in other cases, however, the pathology can manifest itself in a more generalized manner.
Depending on the muscles affected by the disease, various symptoms may occur, including: diplopia, blurred vision, drooping of the eyelids, difficulty swallowing and chewing, gait problems, altered facial expressions, dysarthria, shortness of breath, respiratory acidosis and back pain.
In addition, in some cases, myasthenic crises can occur. These crises are characterized by an involvement of the respiratory muscles that can put the life of patients in serious danger. In fact, the myasthenic crisis requires immediate treatment and hospitalization of the patient.
The information on Myasthenia Gravis - Drugs to Treat Myasthenia Gravis is not intended to replace the direct relationship between health professional and patient. Always consult your doctor and / or specialist before taking Myasthenia Gravis - Drugs to Treat Myasthenia Gravis.
Medicines
Unfortunately, there is no real cure for myasthenia gravis, but some types of treatments can be undertaken to try to slow the course of the disease.
The drugs of first choice, in this case, are cholinesterase inhibitors (a particular enzyme whose task is to degrade acetylcholine). The doctor may also decide to administer corticosteroids and immunosuppressants, to reduce the excessive and abnormal response of the immune system.
In other cases, however, the doctor may deem it necessary to resort to plasmapheresis or surgical removal of the thymus.
The following are the classes of drugs most used in the therapy against myasthenia gravis and some examples of pharmacological specialties; it is up to the doctor to choose the active ingredient and dosage most suitable for the patient, based on the severity of the disease, the state of health of the patient and his response to treatment.
Cholinesterase inhibitors
As mentioned, the first choice treatment of myasthenia gravis is the administration of cholinesterase inhibitor drugs. These drugs, in fact, by inhibiting the enzyme responsible for the degradation of acetylcholine, indirectly increase its bioavailability and ensure that it can compete with autoantibodies for binding with its own receptors placed on the neuromuscular junction.
Among the most used active ingredients, we remember:
- Neostigmine (Prostigmine ®): For the treatment of myasthenia gravis, neostigmine is available for oral and parenteral administration.
When administered orally, the dose of neostigmine usually used is 150 mg, to be administered in divided doses over 24 hours. In the event that oral administration is not possible (as, for example, in the case of myasthenic seizures acute), then neostigmine can be administered intramuscularly or subcutaneously at a dose of 0.5 mg. Subsequent doses to be administered parenterally will be determined by the physician according to the patient's response to therapy. However, not Oral administration should be returned as soon as possible. - Pyridostigmine (Mestinon ®, Pyridostigmine NRIM ®): pyridostigmine is also indicated for the treatment of myasthenia gravis and is available in the form of tablets (prolonged release and not) suitable for oral administration.
The dose of pyridostigmine usually used in the treatment of myasthenia gravis is 60-180 mg, to be taken 2-4 times a day.
The exact amount of medicine to be taken and the frequency of administration must however be determined by the doctor on an individual basis.
Corticosteroids
Corticosteroids are powerful anti-inflammatory drugs that can interfere with the response of the immune system and for this reason they can be useful in the treatment of myasthenia gravis.However - because of the serious side effects they can cause - the use of corticosteroids should be done under close medical supervision and, if possible, should not be continued for long periods.
Among the active ingredients that can be used, we remember prednisone (Deltacortene ®). This drug is available for oral administration. The doses of prednisone usually used can vary from 5 mg to 15 mg of active ingredient per day. However, the exact dosage of the drug must be established by the physician for each patient.
Immunosuppressants
Immunosuppressants - as their name suggests - are drugs capable of suppressing the immune system. With the administration of these drugs, therefore, it is possible to decrease the autoimmune response that characterizes myasthenia gravis and that is triggered against the cholinergic receptors at the level of the neuromuscular junctions.
Among the various types of immunosuppressants that can be used in the treatment of myasthenia gravis, we mention azathioprine (Azafor ®, Azatioprina Aspen ®, Azatioprina Hexal ®). Azathioprine is available for oral administration in tablet form. Generally, the starting dose used is 1-3 mg / kg of body weight per day. However, the exact amount of azathioprine to be administered varies depending on the condition. of each patient and according to the patient's response to therapy, therefore, it must be established by the physician on an individual basis.
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