A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Thioridazine Side Effects, and Drug Interactions - Thioridazine
Thioridazine Side Effects, and Drug Interactions - Thioridazine
SIDE EFFECTS
In the recommended dosage
ranges with thioridazine hydrochloride
most side effects are mild and transient.
Central Nervous System: Drowsiness may be encountered on
occasion, especially where large doses are given early in treatment.
Generally, this effect tends to subside with continued therapy
or a reduction in
dosage. Pseudoparkinsonism and other extrapyramidal
symptoms may occur but are infrequent. Nocturnal confusion,
hyperactivity, lethargy, psychotic
reactions, restlessness and headache
have been reported but are extremely rare.
Autonomic Nervous System: Dryness of mouth,
blurred vision, constipation, nausea, vomiting,
diarrhea, nasal
stuffiness and pallor
have been seen.
Endocrine System: Galactorrhea, breast
engorgement, amenorrhea, inhibition of ejaculation
and peripheral edema
have been described.
Skin: Dermatitis and skin
eruptions of the urticarial
type have been observed
infrequently. Photosensitivity is extremely rare.
Cardiovascular System: ECG
changes have been reported (see Phenothiazine Derivatives: Cardiovascular
Effects below).
Other: Rare cases described as parotid
swelling have been
reported following administration
of thioridazine.
Phenothiazine Derivatives
It should be noted that efficacy,
indications and untoward effects have varied with the different
phenothiazines. It has been reported that old age lowers the tolerance
for phenothiazines. The most common neurological side effects in
these patients are parkinsonism
and akathisia. There appears to be an increased risk
of agranulocytosis
and leukopenia in
the geriatric population. The physician
should be aware that the following have occurred with one or more
phenothiazines
and should be considered whenever one of these drugs is used.
Autonomic Reactions: Miosis, obstipation, anorexia,
paralyltic ileus.
Cutaneous Reactions: Erythema, exfoliative dermatitis,
contact dermatitis.
Blood Dyscrasias: Agranulocytosis, leukopenia,
eosinophilia, thrombocytopenia, anemia,
aplastic anemia, pancytopenia.
Allergic Reactions: Fever, laryngeal
edema, angioneurotic edema,
asthma.
Hepatotoxicity: Jaundice, biliary
stasis.
Cardiovascular Effects: Changes in the terminal
portion of the electrocardiogram,
including prolongation of the Q-T interval,
lowering and inversion
of the T-wave and appearance
of a wave tentatively identified
as a bifid T or a U wave
have been observed in some patients receiving the phenothiazine
tranquilizers, including thioridazine hydrochloride. To date, these
appear to be due to altered repolarization
and not related to myocardial
damage. They appear to be reversible. While there is no
evidence at present
that these changes are in any way precursors of any significant
disturbance of cardiac
rhythm, it should be noted that several sudden and unexpected deaths
apparently due to cardiac
arrest have occurred
in patients previously showing characteristic
electrocardiographic changes while taking the drug. The use of periodic
electrocardiograms has been proposed but would appear to be of questionable
value as a predictive
device. Hypotension, rarely resulting in cardiac
arrest.
Extrapyramidal Symptoms: Akathisia, agitation,
motor restlessness, dystonic
reactions, trismus, torticollis, opisthotonus, oculogyric
crises, tremor, muscular
rigidity, akinesia.
Tardive Dyskinesia: Chronic use of neuroleptics may
be associated with the development
of tardive dyskinesia.
The salient features
of this syndrome are
described in the WARNINGS
section and below.
The syndrome is characterized
by involuntary choreoathetoid
movements which variously involve the tongue, face, mouth,
lips, or jaw (e.g., protrusion
of the tongue, puffing of cheeks, puckering of the mouth,
chewing movements), trunk and extremities. The severity of the syndrome
and the degree of impairment
produced vary widely.
The syndrome may become
clinically recognizable either during treatment, upon dosage
reduction, or upon withdrawal
of treatment. Movements may decrease in intensity
and may disappear altogether if further treatment
with neuroleptics is withheld. It is generally believed that reversibility
is more likely after short rather than long-term neuroleptic
exposure. Consequently, early detection of tardive
dyskinesia is important.
To increase the likelihood of detecting the syndrome
at the earliest possible time, the dosage
of neuroleptic drug should
be reduced periodically (if clinically possible) and the patient
observed for signs of the disorder. This maneuver
is critical, for neuroleptic
drugs may mask the signs
of the syndrome.
Endocrine Disturbances: Menstrual irregularities,
altered libido, gynecomastia,
lactation, weight
gain, edema. False positive
pregnancy tests have been reported.
Urinary Disturbances: Retention, incontinence.
Others: Hyperpyrexia. Behavioral effects suggestive
of a paradoxical reaction
have been reported. These include excitement, bizarre dreams, aggravation
of psychoses and toxic
confusional states. More recently, a peculiar skin-eye syndrome
has been recognized as a side
effect following long-term
treatment with phenothiazines.
This reaction is marked
by progressive pigmentation of areas of the skin
or conjunctiva and/or
accompanied by discoloration of the exposed sclera
and cornea. Opacities of the anterior lens and cornea
described as irregular or stellate
in shape have also been
reported. Systemic lupus
erythematosus-like syndrome.
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