Monostotic fibrous dysplasia is a form of fibrous dysplasia where only one bone is involved. It comprises a majority of the cases of fibrous dysplasia (approximately 70–80%).It is a rare bone disease characterized by the replacement of normal elements of the bone by fibrous connective tissue, which can cause very painful swellings and bone deformities, and make bone abnormally fragile and prone to fracture.A congenital, noninherited, benign anomaly of bone development in a single bone, it consists of the replacement of normal marrow and cancellous bone by immature bone with fibrous stroma. Monostotic fibrous dysplasia occurs with equal frequency in both sexes and normally develops early in life, with lesions frequently identified late in the first and early second decades. Most patients are asymptomatic, with the diagnosis often established after an incidental finding or with pain, swelling, or fracture. Lesions usually enlarge in proportion to skeletal growth and the abnormal replacement remain active only until skeletal maturity.Monostotic fibrous dysplasia does not convert into the polyostotic type. When symptoms are present, they often are nonspecific, including pain, swelling, or pathologic fracture. It most often affects the ribs (28%), proximal femur (23%), tibia, craniofacial bones (10-25%) and humerus (10-25%). See also
Polyostotic fibrous dysplasia

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Palonosetron, sold under the brand name Aloxi, is used for the prevention and treatment of chemotherapy-induced nausea and vomiting (CINV). It is a 5-HT3 antagonist.Palonosetron is administered intravenously, or as a single oral capsule. It has a longer duration of action than  other 5-HT3 antagonists. The oral formulation was approved on August 22, 2008, for prevention of acute CINV alone, as a large clinical trial did not show oral administration to be as effective as intravenous use against delayed CINV. It is on the World Health Organizations List of Essential Medicines.The oral combination netupitant/palonosetron is approved for both acute and delayed CINV. Adverse effects
The most common adverse effects are headache, which occurs in 4–11% of patients, and constipation in up to 6% of patients. In less than 1% of patients, other gastrointestinal disorders occur, as well as sleeplessness, first- and second-degree atrioventricular block, muscle pain and shortness of breath. Palonosetron is similarly well tolerated as other 5-HT3 antagonists, and slightly less than placebo. Interactions
Palonosetron does not relevantly inhibit or induce cytochrome P450 liver enzymes. There are case reports about serotonin syndrome when the drug is combined with serotonergic substances such as selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine reuptake inhibitors (SNRIs), two common types of antidepressants. Pharmacology
Mechanism of action
Palonosetron is a 5-HT3 antagonist, commonly known as a setron. These drugs act by blocking serotonin from binding to the 5-HT3 receptor. Pharmacokinetics
Orally taken palonosetron is absorbed well from the gut and has a bioavailability of 97%.