This is because the disease is relatively rare and the drugs developed are protected by that patent. Because each drug has research and development costs, pharmaceutical companies have a patent protection period in order to recover the costs. This disease is rare and relatively rare. To recover this cost, it will be expensive to spread it to patients. Drugs within the patent protection period are quite expensive.
Disease Introduction
Spinal muscular atrophy (SMA) is a disease caused by the degeneration of motor neurons in the anterior horn of the spinal cord, leading to muscle weakness and atrophy. It is an autosomal recessive genetic disease and is not uncommon clinically. The clinical manifestations of this disease vary greatly. According to the patient's age of onset and clinical course, SMA is divided into 4 types from severe to mild. The most common characteristic is the degeneration of the anterior horn cells of the spinal cord. The clinical manifestations are progressive and symmetrical, with widespread flaccid paralysis and muscle atrophy mainly in the proximal limbs. Intellectual development and sensation are normal.
The clinical manifestations of this disease vary greatly. According to the patient's age of onset and clinical course, SMA is divided into 4 types from severe to mild.
Type 1
Also known as Werdnig-Hoffman disease, the infantile form, accounts for about 45% of all SMA cases. The child's onset of illness occurred within 6 months of birth, with rapidly developing progressive and symmetrical limb weakness, and the maximum motor ability could not reach the level of sitting alone. The muscle weakness is proximal, and due to significant hypotonia, the lower limbs assume a "frog-leg" posture when lying down. The child's expression and eye movements are normal, tongue muscle fasciculations, and oropharyngeal muscle weakness lead to weak crying, weak sucking, weakened gag reflex, and prone to aspiration. Because the intercostal muscles are more heavily involved than the diaphragm, contradictory breathing results and the chest exhibits a characteristic "bell-shaped" deformity. The respiratory muscles are weak and prominent, and most children die of respiratory failure within 2 years of age.
Type 2
Also known as Dubowitz's disease, the intermediate type, accounting for about 30 to 40%. Patients usually develop symptoms 6 to 18 months after birth, and progress more slowly than type 1. The maximum exercise ability can reach the point of sitting alone, but the age of sitting alone may lag behind that of normal children of the same age, and they cannot stand or walk alone. The muscle weakness is proximal, and the lower limbs are heavier than the upper limbs. The facial muscles and extraocular muscles are not affected. The tongue muscles are atrophic with fasciculations. Tendon reflexes in the limbs disappear. Fasciculations can be observed in the distal limbs. As the disease progresses, complications such as dysphagia, weak cough, respiratory insufficiency, scoliosis, and joint contracture appear. Some children lose the ability to sit alone in childhood. Although lifespan is shortened, most survive into adulthood.
Type 3
Also known as Kugelberg-Welander disease, the juvenile type, accounting for about 20%. Most patients develop symptoms after 18 months of life. Early motor development is normal and they can walk alone. Some walk alone is delayed. As age increases, proximal muscle weakness occurs, with the lower limbs being heavier than the upper limbs. Eventually, the patient partially loses the ability to walk alone and becomes increasingly dependent on a wheelchair. As the disease progresses, limb fasciculations and foot deformities may occur. Some patients have scoliosis, respiratory insufficiency, etc. that affect their daily lives, and their life expectancy is not shortened or is slightly reduced.
Type 4
Late-onset, that is, adult type, with normal early motor development, onset in adults, proximal limb weakness, slow progression, and no shortened life expectancy.
Nosinaxin Sodium, a drug for the treatment of children with SMA
On December 23, 2016, Nosinaxin Sodium Injection was approved for the first time in the United States and is the world’s first precise target for SMA. As a therapeutic drug, the drug has subsequently been approved for the treatment of SMA in the European Union, Brazil, Japan, South Korea, Canada and other countries.
On April 28, 2019, Nosinaxin Sodium Injection was launched in China for the treatment of 5qSMA.
Drugs for treating rare diseases are relatively expensive during the patent period. During the patent period, generic drugs did not come out. People need medical treatment, so why are medicines so expensive? ?