INFORMATION FOR HEALTH PROFESSIONALS
Home | Consumers | Health Professionals | Regulatory | Other | Hot Topics | Search
Home | Consumers | Health Professionals | Regulatory | Other | Hot Topics | Search
Hydroxyzine hydrochloride in:
10mg Capsule: Opaque, orange coloured , oval, size 3, soft gelatin capsules containing an off-white , creamy substance; with an imprint of 10 on the capsule.
25mg Capsule: Opaque, green coloured , oval, size 3, soft gelatin capsules containing an off-white , creamy substance; with an imprint of 25 on the capsule.
50mg Capsule: Opaque, red coloured, oval, size 3, soft gelatin capsules containing an off-white, creamy substance; with an imprint of 50 on the capsule
Hydroxyzine hydrochloride, a diphenylmethane derivative is a rapid acting tranquilliser and antihistaminic agent. It induces a calming effect in anxious, tense, psychoneurotic adults and also in anxious hyperkinetic children, without impairing mental alertness. Hydroxyzine’s sedative action may be due to a suppression of activity in certain key regions of the subcortical area of the central nervous system. It is not a cortical depressant. Primary skeletal muscle relaxation and antispasmodic action have also been demonstrated.
Animal studies have demonstrated a number of properties of hydroxyzine, including marked antihistamine activity and primary skeletal muscle relaxation. Spasmolytic action on isolated rabbit jejunum was demonstrated to be 80% that of papaverine hydrochloride.
Hydroxyzine has an antiemetic effect. Vomiting induced in dogs by apomorphine was prevented by oral administration of hydroxyzine 20 mg/kg. Oral administration of hydroxyzine significantly potentiated the analgesic effect of meperidine in rats.
Although hydroxyzine is not a cortical depressant, it has been speculated that its antianxiety effects may be caused by suppression of activity in certain subcortical regions of the central nervous system.
Hydroxyzine hydrochloride suppresses some of the hypothalamic nuclei and extends its effects peripherally in the sympathetic portion of the autonomic nervous system where it depolarizes nervous and muscle fibres. Except in extremely high doses it has no apparent effect on the cerebral, thalamic or spinal cord areas. There is also evidence that part of its activity is caused by a depressant action on the reticular formation. Hydroxyzine inhibits the somatic effects of excitatory drugs such as epinephrine, dextro-amphetamine, mescaline and lysergic acid.
Experimentally, hydroxyzine decreases motor activity by a direct relaxing effect on muscles. Excitable tissues are depolarized. The local anaesthetic effect is equal or greater than that of procaine. The spinal cord and higher centres of the central nervous system are not depressed by the drug and may even show increased activity at very high doses. The hypothalamic and peripheral depressant effects of hydroxyzine in the absence of central depression explain its effect upon the response of experimental animals to cortical stimulants and hallucinatory drugs. Electroencephalographic studies have shown that the excitatory drugs are diminished very little, if any, whereas the behaviour of the animals may be greatly altered. In other words, the electrical impulses are not diminished but the animals appear outwardly calm.
A 0.7 mg/kg dose of hydroxyzine was administered to 7 healthy volunteers and produced a mean peak serum concentration of 72.5 ± 11.1 ng/mL at a mean time of 2.1 ± 0.4 hours. It was not possible to fit the serum hydroxyzine concentration vs time data to a compartment model, since insufficient samples were collected in the absorption phase. A two-compartment model with first-order absorption may be required, as evidenced by visual inspection of the curves.
The mean elimination half-life calculated from the terminal linear portion of the curves was 20.0 + 4.1 hours. This was similar to the mean residence time value of 17.7 + 5.2 hours calculated with the method of statistical moments. The mean clearance rate, 9.78 + 3.25 mL/min/kg, and mean apparent volume of distribution, 16.0 + 3.0 L/kg, were also calculated by nonparametric methods
SERECID is indicated in the management of anxiety and tension as in the preparation for dental procedures and in acute emotional problems.
SERECID is also indicated in the management of anxiety associated with organic disturbances and as adjunctive therapy in alcoholism and allergic conditions with strong emotional overlay, such as in asthma, chronic urticaria, and pruritus.
SERECID is useful in the control of nausea and vomiting.
Dosage is dependent upon the intensity of the emotional disturbance, rather than upon the weight of the patient.
Adults: 25 mg three times a day to 100 mg four times a day.
Children: Under 6 years, 30 to 50 mg daily in divided doses.
Over 6 years, 50 to 100 mg daily in divided doses.
SERECID may potentiate the effects of narcotics, hypnotics, sedatives, pharmacotherapeutic agents or alcohol when the drug is administered in conjunction with these central nervous system depressants.
SERECID should be administered cautiously to epileptic patients. In rare cases, an increase in tendency to seizure has been observed, as well as involuntary motor activity in hospitalised patients receiving high doses of the drug.
Patients should be cautioned against driving a car or operating dangerous machinery while taking SERECID since drowsiness may occur with use of this drug.
SERECID is contraindicated in the early months of pregnancy since studies in rats have shown that hydroxyzine causes foetal abnormalities when given in doses substantially above the human therapeutic range.
Drowsiness may occur in some patients, but is usually transitory. Dryness of the mouth may be encountered at higher doses. Involuntary motor activity, including rare instances of tremor and convulsions, has been reported, usually with doses considerably higher than those recommended.
Not known
The most common manifestation of hydroxyzine overdosage is hypersedation. Hypotension or feeling faint may be another sign of overdose.
If vomiting has not occurred spontaneously, it should be induced. Immediate gastric lavage is also recommended. General supportive care, including frequent monitoring of the vital signs and close observation of the patient is indicated. Hypotension, though unlikely may be controlled with intravenous fluids and norepinephrine or metaraminol. Do not use epinephrine since hydroxyzine counteracts its pressor action. Caffeine and sodium benzoate injection may be used to treat CNS depressant effects.
Protect from light and moisture. Store below 30°C.
Prescription Medicine.
30 capsules
Hydroxyzine hydrochloride is (±) -2- [2- {4- (p-chloro-α-phenylbenzyl) -1-piperazinyl} ethoxy] ethanol dihydrochloride. Its molecular formula and molecular weight are C21H27ClN2O2.2HCl and 447.83 respectively.
Lincoln Pharmaceuticals
A Division of Douglas Pharmaceuticals Ltd
Central Park Drive, Lincoln
PO Box 45-027
AUCKLAND 8
Ph: (09) 835-0660
Fax: (09) 835-0665
19 August 1999