A fluorine atom at the 3′ position practically doubles in vitro and in vivo activity, and the electron-donating nitrogen atom in the morpholine ring helps maintain high antibiotic potency and an acceptable safety profile.The anticoagulant rivaroxaban (Xarelto) bears a striking structural similarity to linezolid; both drugs share the oxazolidinone pharmacophore, differing in only three areas (an extra ketone and chlorothiophene, and missing the fluorine atom). However this similarity appears to carry no clinical significance. Synthesis
Linezolid is a completely synthetic drug: it does not occur in nature (unlike erythromycin and many other antibiotics) and was not developed by building upon a naturally occurring skeleton (unlike most beta-lactams, which are semisynthetic). Many approaches are available for oxazolidinone synthesis, and several routes for the synthesis of linezolid have been reported in the chemistry literature. Despite good yields, the original method (developed by Upjohn for pilot plant-scale production of linezolid and eperezolid) is lengthy, requires the use of expensive chemicals—such as palladium on carbon and the highly sensitive reagents methanesulfonyl chloride and n-butyllithium—and needs low-temperature conditions. Much of the high cost of linezolid has been attributed to the expense of its synthesis. A somewhat more concise and cost-effective route better suited to large-scale production was patented by Upjohn in 1998.Later syntheses have included an "atom-economical" method starting from D-mannitol, developed by Indian pharmaceutical company Dr. Reddys and reported in 1999, and a route starting from (S)-glyceraldehyde acetonide (prepared from ascorbic acid), developed by a team of researchers from Hunan Normal University in Changsha, Hunan, China.
Deactivating the F protein prevents the virus from fusing with its targets cell membrane and prevents the virus from entering the host cell. Pharmacodynamics
Palivizumab has demonstrated a significantly higher affinity and potency in neutralizing both A and B subtypes of RSV when compared with RSV-IGIV. Treatment with 2.5 mg/kg of palivizumab led to a serum concentration of 25-30 μg/mL in cotton rats and reduced RSV titers by 99% in their lungs. Pharmacokinetics
Absorption
A 2008 meta-analysis found that palivizumab absorption was quicker in the pediatric population compared to adults (ka = 1.01/day vs. ka = 0.373/day). The intramuscular bioavailability of this drug is approximately 70% in healthy young adults. Current recommendation for RSV immunoprophylaxis is administration of 5 x 15 mg/kg doses of palivizumab to maintain body concentrations above 40 μg/mL. Distribution
The volume of distribution is approximately 4.1 liters. Clearance
Palivizumab has a drug clearance (CL) of approximately 198 ml/day. The half-life of this drug is approximately 20 days with three doses sustaining body concentrations that will last the entire RSV season (5 to 6 months). A 2008 meta-analysis estimated clearance in the pediatric population by considering maturation of CL and body weight which showed a significant reduction compared to adults. Side effects
Palivizumab use may cause side effects, which include, but are not limited to:
Sore throat
Runny nose
Redness or irritation at the injection site
Vomiting
DiarrheaSome more serious side effects include:

Severe skin rash
Itching
Hives (urticaria)
Difficulty breathing

Contraindications
Contraindications for the use of palivizumab include hypersensitivity reactions upon exposure to palivizumab. Serious cases of anaphylaxis have been reported after exposure to palivizumab.