That said responses, especially those which are partial, can be delayed. Quite what an adequate trial of clozapine is, is uncertain but a recommendation is that this should be for at least 8 weeks on a plasma trough level above 350-400 micro g/L. There is considerable inter-individual variation. A significant number of patients respond at lower and also much higher plasma concentrations and some patients, especially young male smokers may never achieve these plasma levels even at doses of 900 mg/day. Options then include either increasing the dose above the licensed maximum or the addition of a drug that inhibits clozapine metabolism. Avoiding unnecessary polypharmacy is a general principle in drug treatment. Optimising blood sampling
The neutrophil cut off for clozapine have shown an exceptional ability to mitigate the risk of neutropenia and agranulocytosis. There is a significant margin of safety. Some patients may have marginal neutrophil counts before and after initiation and they are at risk of premature clozapine discontinuation. A knowledge of neutrophil biology allows blood sampling optimisation. Neutrophils show a diurnal variation in response to the natural cycle of G-CSF production, they are increased in the afternoons, they are also mobilised into the circulation after exercise and smoking. Simply shifting blood sampling has been shown to avoid unnecessary discontinuations, especially in black populations. However this is a disruption to usual hospital practice. Other practical steps are to ensure that blood results become available in hours and when senior staff are available.
Nusinersen, marketed as Spinraza, is a medication used in treating spinal muscular atrophy (SMA), a rare neuromuscular disorder. In December 2016, it became the first approved drug used in treating this disorder. Since the condition it treats is so rare, Nusinersen has so-called "orphan drug" designation in the United States and the European Union. Medical uses
The drug is used to treat spinal muscular atrophy associated with a mutation in the SMN1 gene. It is administered directly to the central nervous system (CNS) using intrathecal injection.In clinical trials, the drug halted the disease progression. In around 60% of infants affected by type 1 spinal muscular atrophy, it improves motor function. Side effects
People treated with nusinersen had an increased risk of upper and lower respiratory infections and congestion, ear infections, constipation, pulmonary aspiration, teething, and scoliosis. There is a risk that growth of infants and children might be stunted. In older clinical trial subjects, the most common adverse events were headache, back pain, and other adverse effects from the spinal injection, such as post-dural-puncture headache.Although not observed in the trial patients, a reduction in platelets as well as a risk of kidney damage are theoretical risks for antisense drugs and therefore platelets and kidney function should be monitored during treatment.In 2018, several cases of communicating hydrocephalus in children and adults treated with nusinersen emerged; it remains unclear whether this was drug related. Pharmacology
Spinal muscular atrophy is caused by loss-of-function mutations in the SMN1 gene which codes for survival motor neuron (SMN) protein.