Discontinuation
The British National Formulary recommends a gradual withdrawal when discontinuing antipsychotics to avoid acute withdrawal syndrome or rapid relapse. Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite. Other symptoms may include restlessness, increased sweating, and trouble sleeping. Less commonly there may be a feeling of the world spinning, numbness, or muscle pains. Symptoms generally resolve after a short period of time.There is tentative evidence that discontinuation of antipsychotics can result in psychosis. It may also result in reoccurrence of the condition that is being treated. Rarely tardive dyskinesia can occur when the medication is stopped. Pharmacology
Pharmacodynamics
Perphenazine has the following binding profile towards cloned human receptors unless otherwise specified:
Acronyms:
RS — Rat striatum receptor. RB — Rat brain receptor. Pharmacokinetics
Perphenazine has an oral bioavailability of approximately 40% and a half-life of 8 to 12 hours (up to 20 hours), and is usually given in 2 or 3 divided doses each day. It is possible to give two-thirds of the daily dose at bedtime and one-third during breakfast to maximize hypnotic activity during the night and to minimize daytime sedation and hypotension without loss of therapeutic activity. Formulations
It is sold under the brand names Trilafon (single drug) and Etrafon/Triavil/Triptafen (contains fixed dosages of amitriptyline). A brand name in Europe is Decentan pointing to the fact that perphenazine is approximately 10-times more potent than chlorpromazine. Usual oral forms are tablets (2, 4, 8, 16 mg) and liquid concentrate (4 mg/ml). The Perphenazine injectable USP solution is intended for deep intramuscular (i.m.)
Prax may refer to:

Prax (malware), or Regin, a malware and hacking toolkit
Prax Group, operators of Lindsey Oil Refinery, North Killingholme, North Lincolnshire, England
Praso, Italy (German: Prax), a former comune in Trentino, Italy
Mike Prax (born 1956), American politician from Alaska
Valentine Prax (1897–1981), French expressionist and cubist painter