Synonym: haldol Chemical name: 4-[4-(p-chlorophenyl)-4-hydroxypiperidol]-4’-fluorobutyrophenone CAS: 52-86-8 MF: C21H23ClFNO2 FW: 375.9 Solubility: insoluble in water; soluble in ethanol and DMSO. Major uses Haloperidol is a neuroleptic drug for the treatment of psychotic disorders (e.g. schizophrenia, mania, psychopathy etc.). It is also a widely used tranquilizer (e.g. for treatment of behavioral problems in hyperactive children) [1]. Haloperidol may be used as a drug of abuse [2]. Human toxicity Most common major signs of acute intoxication at a massive overdose are the central nervous system (CNS) depression, somnolence, coma, respiratory depression, cardiac dysrhythmia and hypotension. The recommended daily dose for patients with moderate symptoms is 1 to 6 mg, and for patients with severe symptoms, 6 to 15 mg. Maximum tolerated doses are between 300 and 1000 mg [2]. In adults, ingestion of 300 mg or more have experienced life-threatening symptoms. Some individuals have had fatal reactions to even therapeutic doses of haloperidol. At the same time, it happened that adults survived overdoses as large as 1000 mg [2]. Therapeutic blood plasma concentrations are in the range of 0.005-0.02 mg/l [3]. In patients who respond to haloperidol, a serum concentration of at least 0.005 mg/l is advisable to ensure a positive response. Side effects increased in incidence with plasma concentrations greater than 0.006 mg/l, at 12 to 14 h after the final administration [4]. The toxic plasma/serum level of haloperidol was reported to be 0.005-0.05 mg/l [5]. The lethal blood levels have not been definitively established; however, in one fatal case with suicidal overdose, post mortem heart blood concentration of haloperidol was 1.9 mg/l (5 μM)); in second fatal case, which was believed to be a natural cardiac death, heart blood concentration of haloperidol was 0.6 mg/l (1.6 μM) [6]. Kinetic data [4] Absorption: haloperidol is well absorbed from the gastrointestinal tract. Volume of distribution (Vd): 20 l/kg. Blood protein bindning: 90-94%. Peak serum concentration levels are attained 0.5 to 4 h after an oral dose. Elimination: clearance occurs exclusively by hepatic metabolism. The elimination half-life ranges from 13 to 35 h. Metabolism and excretion Haloperidol is mainly metabolized by the liver, where it undergoes cytochrome P450- catalyzed oxidative cleavage of hydrocarbon chain, forming inactive fluorophenyl and piperidine metabolites. An additional metabolic pathway involves reduction of the keto group on the side chain to an alcohol, forming a compound known as reduced haloperidol. The latter has about 25% of the antipsychotic activity of the parent drug (reviewed in [6]). Other identified metabolites include 4-fluorobenzol-propionic acid and 4-fluoro- phenylaceturic acid [2]. Excretion: Renal excretion is negligible, with less than 1% of an administered dose excreted in the urine. Pharmacological and toxicological mechanisms Similar to the other neuroleptics, haloperidol is a dopamine receptor antagonist: it blocks D-2 dopamine receptors in the brain. Thus, the antipsychotic activity of this anticholinergic drug is closely associated with its ability to block the action of dopamine [1, 2]. The toxic effect of haloperidol is related to blocking of dopamine receptors in the CNS; however, the knowledge of exact mechanisms is still meager [1]. Target organs: CNS, heart, liver [1]. References 1. Haddad, L.M., Winchester, J.F. (1990) Clinical Management of Poisoning and Drug Overdose. 2nd ed., pp. 780-793. W.B. Saunders Company. 2. Poisindex, Thomson Micromedex (2005). 3. Cheng, V.A., Paalzow, L.K., Bondesson, U., Ekblom, B., Eriksson, K., Eriksson, S.O., Lindberg, A., Lindström, L. (1987) Pharmacokinetics of haloperidol in psychotic patients. Psychopharmacology 91, 410-414. 4. Ellenhorn, M.J., Schonwald, S., Ordog, G., Wasserberger, J. (1997) Ellenhorn’s Medical Toxicology: Diagnosis and Treatment of Human Poisoning, 2nd ed., pp. 674- 675. Williams & Wilkins. 5. Winek, C.L. (1994) Drug and chemical blood-level data. Winek’s Toxicological Annual, Pittsburgh. Allegheny County Department Laboratories. 6. Levine, B.S., Wu, S.C., Goldberger, B.A., Caplan, Y.H. (1991) Two fatalities involving haloperidol. J Anal Toxicol 15, 282-284. Written by Ada Kolman, December 2005; revised March 2007
Over time, your teeth can become stained and “yellow” as a result of diet, environmental and lifestyle factors such as smoking and red wine. There are many different methods used to help whiten your teeth, and as you will find, some work much better than others. Tooth whitening refers to anything that can change the shade of your teeth and generally relies on some form of “bleaching” pro
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