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Each capsule contains 100mg of Secobarbital Sodium






Therapeutic Indications
For the short term treatment of severe, intractable insomnia in patients already
taking barbiturates. New patients should not be started on this preparation.
Attempts should be made to wean patients off this preparation by gradual
reduction of the dose over a period of days or weeks (see drug abuse and
dependence). Abrupt discontinuation should be avoided as this may
precipitate withdrawal effects (see warnings).


Posology and Method of Administration
For oral administration to adults only. Normal dosage is 100 mg at bedtime.
Seconal Sodium is not recommended for use in elderly or debilitated patients.
Seconal should not be administered to children or young adults.
In studies, Secobarbital sodium has been found to lose most of its
effectiveness for both inducing and maintaining sleep by the end of two weeks
of continued drug administration, even with the use of multiple doses.


Hypersensitivity to barbiturates, a history of manifest or latent porphyria, marked
impairment of liver function or respiratory disease in which dyspnoea or obstruction
is evident.
Barbiturates should not be administered to children, young adults, patients with a
history of drug or alcohol addiction or abuse, the elderly and the debilitated.


Special warnings and precautions for use
Addiction potential: Secobarbital sodium may be habit forming. Tolerance and
psychological and physical dependence may occur with continued use. Patients who
have psychological dependence on barbiturates may increase the dosage or decrease
the dosage interval without consulting a doctor and, subsequently, may develop a
physical dependence on barbiturates.
To minimise the possibility of overdosage or development of dependence, the amount
prescribed should be limited to that required for the interval until the next
Withdrawal symptoms occur after long term normal use (and particularly after abuse)
on rapid cessation of barbiturate treatment. Symptoms include nightmares, irritability
and insomnia and, in severe cases,tremors, delirium, convulsions and death.
Barbiturates should be withdrawn gradually from any patient known to be taking
excessive doses over long periods.
Caution should be exercised when barbiturates are administered in the presence of
acute or chronic pain, because paradoxical excitement could be induced or important
symptoms could be masked.
Information for patients: The following information should be given to patients
receiving Secobarbital:
The use of Secobarbital carries with it an associated risk of psychological and/or
physical dependence. The patient should be warned against increasing the dose of
the drug without consulting a doctor.
Secobarbital may impair the mental and/or physical abilities required for the

performance of potentially hazardous tasks, such as driving a car or operating
machinery. The patient should be cautioned accordingly.
Alcohol should not be consumed while taking Secobarbital. The concurrent use of
Secobarbital with other CNS depressants (eg alcohol, narcotics, tranquillisers and
antihistamines) may result in additional CNS depressant effects.
Drug abuse and dependence: Barbiturates may be habit forming;
tolerance,psychological and physical dependence may occur especially following
prolonged use of high doses. Daily administration in excess of 400 mg Secobarbital,
for approximately 90 days, is likely to produce some degree of physical dependence.
A dosage of 600 - 800 mg, for at least 35 days, is sufficient to produce withdrawal
seizures. The average daily dose for the barbiturate addict is usually about 1.5g.
As tolerance to barbiturates develops, the amount needed to maintain the same level
of intoxication increases; tolerance to a fatal dosage, however, does not increase more
than twofold. As this occurs, the margin between intoxicating dosage and fatal
dosage becomes smaller. The lethal dose of a barbiturate is far less if alcohol is also
Symptoms of acute intoxication include unsteady gait, slurred speech and sustained
nystagmus. Mental signs of chronic intoxication include confusion, poor judgement,
irritability, insomnia and somatic complaints.
The symptoms of barbiturate withdrawal can be severe and may cause death. Minor
withdrawal symptoms may appear 8 to 12 hours after the last dose of a barbiturate.
These symptoms usually appear in the following order: anxiety, muscle twitching,
tremor of hands and fingers, progressive weakness, dizziness, distortion in visual
perception, nausea, vomiting, insomnia and orthostatic hypotension. Major
withdrawal symptoms (convulsions and delirium) may occur within 16 hours and last
up to five days after abrupt cessation of barbiturates. Intensity of withdrawal
symptoms gradually declines over a period of approximately 15 days. Individuals
susceptible to barbiturate abuse and dependence include alcoholics and opiate
abusers, as well as other sedative-hypnotic and amphetamine abusers.
Dependence on barbiturates arises from repeated administration on a continuous
basis, generally in amounts exceeding therapeutic dose levels. Treatment of
dependence consists of cautious and gradual withdrawal of the drug. Barbituratedependent patients can be withdrawn by using a number of withdrawal regimens. In
all cases, withdrawal takes an extended period. One method involves substituting a
30 mg dose of Phenobarbital for each 100 - 200 mg dose of barbiturate that the
patient has been taking. The total daily amount of Phenobarbital is then administered
in three or four divided doses, not to exceed 600 mg daily. Should signs of
withdrawal occur on the first day of treatment, a loading dose of 100 to 200 mg of
Phenobarbital may be administered intramuscularly in addition to the oral dose. After
stabilisation on Phenobarbital, the total daily dose is decreased by 30 mg a day as
long as withdrawal is proceeding smoothly. A modification of this regimen involves
initiating treatment at the patient’s regular dosage level and decreasing the daily
dosage by 10% as tolerated by the patient.

Infants that are physically dependent on barbiturates may be given Phenobarbital, 3 to
10 mg/kg/day. After withdrawal symptoms (hyperactivity, disturbed sleep, tremors
and hyperreflexia) are relieved, the dosage of Phenobarbital should be gradually
decreased and completely withdrawn over a two week period.
Carcinogenesis: Animal data show that Phenobarbital can be carcinogenic after
lifetime administration.
Human data: In a 29 year epidemiological study of 9136 patients who were treated
on an anticonvulsant protocol that included Phenobarbital, results indicated a higher
than normal incidence of hepatic carcinoma. Previously some of these patients had
been treated with thorotrast, a drug that is known to produce hepatic carcinomas.
Thus, this study did not provide sufficient evidence that Phenobarbital is carcinogenic
in humans.
A retrospective study of 84 children with brain tumours, matched to 73 normal
controls and 78 cancer controls (malignant disease other than brain tumours),
suggested an association between exposure to barbiturates prenatally and an increased
incidence of brain tumours.
Barbiturates should be administered with caution, if at all, to patients who are
mentally depressed or have suicidal tendencies. They should also be used with great
caution and at reduced dosage in those with hepatic disease, marked renal
dysfunction, shock or respiratory depression.
Elderly or debilitated patients may react to barbiturates with marked excitement,
depression or confusion (see ‘Contra-indications’). In some persons, barbiturates
repeatedly produce excitement rather than depression.
Barbiturates should not be administered to patients showing the premonitory signs of
hepatic coma (see ‘Contra-indications’).
A cumulative effect may occur with the barbiturates leading to features of chronic
poisoning including headache, depression and slurred speech.
Automatism may follow the use of a hypnotic dose of barbiturate
Laboratory tests: Prolonged therapy with barbiturates should be accompanied by
periodic evaluation of, for examplethe haematopoietic, renal and hepatic systems (but
see ‘Uses).

4.5. Interactions with other Medicinal Products and other forms of
Toxic effects and fatalities have occurred following overdoses of Secobarbital
alone and in combination with other CNS depressants. Caution should be
exercised in prescribing unnecessarily large amounts of Secobarbital for
patients who have a history of emotional disturbances or suicidal ideation or
who have misused alcohol or other CNS drugs.
Anticoagulants, Antivirals, Calcium-channel Blockers, Ciclosporin,
Levothyroxine, Theophylline : Barbiturates cause induction of the liver
microsomal enzymes responsible for metabolising many other drugs. In
particular they may result in increased metabolism, reduced plasma
concentrations and decreased clinical response to: Oral anticoagulants (eg
warfarin); antivirals (eg indinavir, nelfinavir, saquinavir); calcium-channel
blockers (eg diltiazem, felodipine, isradipine, nicardipine, nifedipine,
verapamil); ciclosporin; levothyroxine (thyroxine); theophylline. Patients
stabilised on any of these therapies may require dosage adjustments if
barbiturates are added to, or withdrawn from, their regimen.
Corticosteroids: Barbiturates appear to enhance the metabolism of exogenous
corticosteroids and steroid dosage may also need adjustment.
Griseofulvin: Barbiturates may interfere with the absorption of oral
griseofulvin, thus decreasing its blood level. Concomitant administration
should be avoided if possible.
Doxycycline: Barbiturates may shorten the half-life of doxycycline for as long
as two weeks after the barbiturate is discontinued. If administered
concomitantly the clinical response to doxycycline should be monitored
Phenytoin, Sodium Valproate, Valproic Acid: The effect of barbiturates on
phenytoin metabolism is variable. Phenytoin and barbiturate blood levels
should be monitored more frequently if administered concomitantly. Sodium
valproate and valproic acid increase Secobarbital serum levels. Therefore
these levels should be monitored and dosage adjustments made as clinically
CNS Depressants: Concomitant use of other CNS depressants, including other
sedatives or hypnotics, antihistamines, tranquillisers or alcohol, may produce
additive depressant effects.
Monoamine Oxidase Inhibitors (MAOIS): Prolong the effects of barbiturates.
Oestradiol, oestrone, progesterone and other steroidal hormones: There have
been reports of patients treated with antiepileptic drugs (eg Phenobarbital)
who became pregnant while taking oral contraceptives. Barbiturates may
decrease the effect of oestradiol. An alternative contraceptive method might
be suggested to women taking barbiturates.


Pregnancy and Lactation
Usage in Pregnancy: Barbiturates are contraindicated during pregnancy since
they can cause foetal harm. A higher than expected incidence of foetal
abnormalities may be connected with maternal consumption of barbiturates.
Barbiturates readily cross the placental barrier and are distributed throughout
foetal tissues with highest concentrations in placenta, foetal liver and brain.
Withdrawal symptoms occur in infants born to women who receive
barbiturates during the last trimester of pregnancy. If a patient becomes
pregnant whilst taking this drug, she should be told of the potential hazard to
the foetus.
Reports of infants suffering from long term barbiturate exposure in utero
included the acute withdrawal syndrome of seizures and hyper-irritability from
birth to a delayed onset of up to 14 days.
Labour and Delivery: Respiratory depression has been noted in infants born
following the use of barbiturates during labour. Premature infants are
particularly susceptible. Resuscitation equipment should be available.
Nursing Mothers: Small amounts of barbiturates are excreted in the milk and
they are therefore contraindicated for the nursing mother.


Effects on Ability to Drive and Use Machines
Secobarbital may impair the mental and/or physical abilities required for the
performance of potentially hazardous tasks such as driving a car or operating
machinery. The patient should be cautioned accordingly


Undesirable Effects
The following adverse reactions and their incidences were compiled from
surveillance of thousands of hospitalised patients who received barbiturates.
As such patients may be less aware of certain of the milder adverse effects of
barbiturates, the incidence of these reactions may be somewhat higher in fully
ambulatory patients.
More than 1 in 100 patients: The most common adverse reaction, estimated
to occur at a rate of 1 to 3 patients per 100, is the following:

LESS THAN 1 IN 100 PATIENTS: Adverse reactions estimated to occur at a
rate of less than 1 in 100 patients are listed below grouped by organ system
and by decreasing frequency:
NEUROLOGICAL: Agitation, confusion, hyperkinesia, ataxia, CNS
depression, nightmares, nervousness, psychiatric disturbance, hallucinations,
insomnia, anxiety, dizziness, abnormal thinking.
RESPIRATORY: Hypoventilation, apnoea.
CARDIOVASCULAR: Bradycardia, hypotension, syncope.
DIGESTIVE: Nausea, vomiting, constipation
OTHER: Headache, hypersensitivity reactions (angioneurotic oedema, rashes,
exfoliative dermatitis), fever, liver damage. Hypersensitivity is more likely to
occur in patients with asthma, urticaria or angioneurotic oedema.
Megaloblastic anaemia has followed chronic Phenobarbital use.


The toxic dose of barbiturates varies considerably. In general, an oral dose of
1g of most barbiturates produces serious poisoning in an adult. Death
commonly occurs after 2 to 10g of ingested barbiturate. The sedative,
therapeutic blood levels of Secobarbital range between 0.5 and 5 mg/l; the
usual lethal blood level ranges from 15 to 40 mg/l. Barbiturate intoxication
may be confused with alcoholism, bromide intoxication and various
neurological disorders. Potential tolerance must be considered when
evaluating significance of dose and plasma concentration.
In extreme overdose, all electrical activity in the brain may cease, in which
case a “flat” EEG normally equated with clinical death cannot be accepted.
This effect is fully reversible unless hypoxic damage occurs. Consideration
should be given to the possibility of barbiturate intoxication even in situations
that appear to involve trauma.
SIGNS AND SYMPTOMS: Symptoms of oral overdose may occur within 15
minutes and begin with CNS depression, absent or sluggish reflexes,
underventilation, hypotension and hypothermia, which may progress to
pulmonary oedema and death. Haemorrhagic blisters may develop, especially
at pressure points.
Complications such as pneumonia, pulmonary oedema, cardiac arrhythmias,
congestive heart failure and renal failure may occur. Uraemia may increase
CNS sensitivity to barbiturates if renal function is impaired. Differential
diagnosis should include hypoglycaemia, head trauma, cerebrovascular
accidents, convulsive states and diabetic coma.

General management should consist of symptomatic and supportive therapy.
charcoal may be more effective than emesis or lavage. Diuresis and peritoneal
dialysis are of little value. Haemodialysis and haemoperfusion enhance drug
clearance and should be considered in serious poisoning. If the patient has
chronically abused sedatives, withdrawal reactions may be manifest following
acute overdose.




Pharmacodynamic Properties
Seconal Sodium (Secobarbital sodium), a short acting barbiturate, is a CNS
depressant. In ordinary doses the drug acts as a sedative and hypnotic.
Barbiturates are capable of producing all levels of CNS mood alteration, from
excitation to mild sedation, hypnosis and deep coma. Overdosage can product
death. Barbiturates depress the sensory cortex, decrease motor activity, alter
cerebellar function and produce drowsiness, sedation and hypnosis.
Barbiturate-induced sleep differs from physiologic sleep. Sleep laboratory
studies have demonstrated that barbiturates reduce the amount of time spent in
the rapid eye movement (REM) phase of sleep, or dreaming stage. Also stages
III and IV sleep are decreased. Following abrupt cessation of barbiturates
used regularly, patients may experience markedly increased dreaming,
nightmares and/or insomnia. Therefore, withdrawal of a single therapeutic
dose over five or six days has been recommended to lessen the REM rebound
and disturbed sleep which contribute to drug withdrawal syndrome (for
example, decrease the dose from 3 to 2 doses a day for 1 week).


Pharmacokinetic Properties
Barbiturates are weak acids that are absorbed and rapidly distributed to all
tissues and fluids, with high concentrations in the brain, liver and kidneys.
Lipid solubility of the barbiturates is the dominant factor in their distribution
within the body. Barbiturates are bound to plasma and tissue proteins; the
degree of binding increases as a function of lipid solubility. The onset of
action of Seconal Sodium is from 10 to 15 minutes and the duration of action
ranges from 3 to 4 hours. The plasma half life of Seconal Sodium is 15 - 40
Secobarbital sodium has a high lipid solubility, plasma protein binding, brain
protein binding, a short delay in onset of activity and a short duration of

Seconal is metabolised primarily by the hepatic microsomal enzyme system
and the metabolic products are excreted in the urine and, less commonly, in
the faeces. Seconal is detoxified in the liver.


Preclinical Safety Data
Carcinogenesis: Animal data show that phenobarbital can be carcinogenic
after lifetime administration.




List of excipients
Starch, Silicone, Erythrosine, Quinoline yellow, Gelatin, Black Iron Oxide,


Not applicable.


Shelf Life
60 months.


Special Precautions for Storage
Store below 25°C. Keep lid tightly closed.


Nature and Contents of Container
High density polyethylene bottles with screw caps containing 100 capsules.


Instruction for Use/Handling
Not applicable.


Flynn Pharma Ltd.
Alton House,
4 Herbert Street
Dublin 2,
Republic of Ireland


PL 13621/0003





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Source: Medicines and Healthcare Products Regulatory Agency

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