Vasopressor
Phenylephrine is commonly used as a vasopressor to increase the blood pressure in unstable patients with hypotension, especially resulting from septic shock. Such use is common in anesthesia or critical-care practices; it is especially useful in counteracting the hypotensive effect of epidural and subarachnoid anesthetics, as well as the vasodilating effect of bacterial toxins and the inflammatory response in sepsis and systemic inflammatory response syndrome. The elimination half life of phenylephrine is about 2.5 to 3.0 hours. The clinical effects of a single intravenous bolus dose of phenylephrine are short lived and needs to be repeated every 10–15 minutes. Commonly the drug is given as a carefully titrated intravenous infusion with a syringe pump or volumetric pump. Because of its vasoconstrictive effect, phenylephrine can cause severe necrosis if it infiltrates the surrounding tissues. Because of this, it should be given through a central line if at all possible. Damage may be prevented or mitigated by infiltrating the tissue with the alpha blocker phentolamine by subcutaneous injection.Phenylephrine hydrochloride at 0.25% is used as a vasoconstrictor in some suppository formulations.Recently, Phenylephrine has been used to treat conditions of orthostatic intolerance such as postural orthostatic tachycardia syndrome - where by activation of venous alpha 1 adrenoreceptors increases venous return and stroke volume which improves symptoms. Priapism
Phenylephrine is used to treat priapism. It is diluted with normal saline and injected directly into the corpora cavernosa. The mechanism of action is to cause constriction of the blood vessels entering into the penis, thus causing decreased blood flow and relieving the priapism.
Vanishing bile duct syndrome is a loose collection of diseases which leads to the injury to hepatic bile ducts and eventual ductopenia. Signs and symptoms
The presentation is dependent upon the underlying cause. The course can be rapid or chronic. Fatigue
Anorexia
Abdominal pain
Weight loss
Pruritus
Hyperlipidemia
Malabsorption
Fat-soluble vitamin deficiencies
Elevated alkaline phosphatase
Elevated gamma-glutamyltransferase
Elevated conjugated bilirubin

Cause
Congenital
In fetal and neonatal life the ductal plates are remodeled. The malformations can be atretic or fibrocystic. Atretic causes
Intrahepatic bile duct atresia (Alagille syndrome) (ALGS2 MIM:610205 and ALGS1 MIM:118450)
Extrahepatic bile duct atresia

Fibrocystic causes
Autosomal recessive polycystic kidney disease
Congential hepatic fibrosis
Carolis disease
Von Meyenburg complex

Chromosomal associations
Trisomy 17, 18 and 21

Genetic associations
Cystic fibrosis
Alpha 1 antitrypsin deficiency
Trihydroxycoprostanic acidemia
Bylers disease

Immunologic associations
Bile duct injury and loss can result from autoimmune destruction. T cells recognize biliary epithelial cell antigens causing injury and eventual atresia. Other causes
Primary biliary cirrhosis
Primary sclerosing cholangitis
Hodgkins lymphoma
Chronic graft-versus-host disease
Drugs(chlorpromazine)/Toxins
Ischemia

Diagnosis
Treatment
Treatment is dependent upon the underlying cause. Treatment is supportive as it is not possible to induce regrowth of lost ducts. Medical therapies
Ursodeoxycholic acid
Immunosuppression
General consensus is that more studies are needed before this can be considered
Organ transplant

References
External links
Uptodate:Hepatic ductopenia and vanishing bile duct syndrome