vasodilator with central effects and has been advocated as a physical and mental geriatric
performance enhancer. Other ergot alkaloids have a hypotensive effect and also cause
smooth-muscle contraction, specifically in the uterus. This property is utilized in obstet-
rics to stop postpartum bleeding. There is a structural correlation between DA and ergot
alkaloids: the parent tetracyclic indole acid, lysergic acid, can be considered as con-
taining an extended phenylethylamine moiety. Amides of lysergic acid are hallucino-
gens and will be discussed among serotonergic drugs.
A novel and very interesting group of compounds is represented by bromocriptine
(4.87). It is used in parkinsonism and for inhibiting the excessive excretion of prolactin,
a peptide hormone of the pituitary that regulates lactation. It also inhibits the secretion
ofgrowth hormone, another product of the anterior pituitary, and has been evaluated
in the treatment of acromegaly, a form of gigantism arising from excessive growth
hormone production.
4.4.3.2 Dopamine Antagonists (Neuroleptics)
The medicinal chemistry of dopamine antagonists (antidopaminergics) is dominated by
endeavors to design therapeutic molecules for major psychiatric disorders such as psy-
chosis. Psychosis is a severe psychiatric disorder in which mental functioning is suffi-
ciently impaired to interfere with the patient’s capacity to meet the normal demands of
everyday life. This impairment involves a marked inability to correctly interpret reality,
and is often accompanied by severe distortions of perception, intellectual functioning,
mood, motivation, and behavior, together with personality decompensation and regres-
sion. The individual has little, if any, insight into either the nature or severity of his or
her disturbance. There are many types of psychosis, including schizophrenia,paranoid
psychosisandaffective psychosis.
Schizophrenia is a complex group of psychotic disorders manifested by typical dis-
turbances of thinking, mood, and behavior. The associated disintegration of mental
status is attributable to a thought disorder, accompanied by misinterpretations of
reality and frequently by delusions and hallucinations (i.e., they may believe that some
external force is controlling their mind and actions). The term schizophrenia has
generally been misinterpreted as meaning “splitting of the mind”; there is a popular
misconception that this involves multiple, split personalities. (This Dr Jekyll/Mr Hyde
view of schizophrenia as a state characterized by alternating, conflicting personalities
is incorrect.) In schizophrenia, the split consists of incongruity between the individual’s
various mental functions, such as a fragmentation between thought content and
NEUROTRANSMITTERS AND THEIR RECEPTORS 243