What happens if I overdose Phenobarbitone GPO?
Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include cold, clammy skin; change in size of pupil; deep sleep; loss of consciousness; slowed or fast breathing.
Proper storage of Phenobarbitone GPO tablets:
Store Phenobarbitone GPO tablets at room temperature (59 to 86 degrees F; 15 to 30 degrees C) in a tightly closed container. Store away from heat, moisture, and light. Do not store in the bathroom. Keep Phenobarbitone GPO tablets out of the reach of children and away from pets.
Overdose of Phenobarbitone GPO in details
Signs and Symptoms
The onset of symptoms following a toxic oral exposure to Phenobarbitone GPO may not occur until several hours following ingestion. The toxic dose of barbiturates varies considerably. In general, an oral dose of 1 g of most barbiturates produces serious poisoning in an adult. Death commonly occurs after 2 to 10 g of ingested barbiturate. The sedated, therapeutic blood levels of Phenobarbitone GPO range between 5 to 40 mcg/mL; the usual lethal blood level ranges from 100 to 200 mcg mL. Barbiturate intoxication may be confused with alcoholism, bromide intoxication, and various neurologic disorders. Potential tolerance must be considered when evaluating significance of dose and plasma concentration.
The manifestations of a long-acting barbiturate in overdose include nystagmus, ataxia, CNS depression, respiratory depression, hypothermia, and hypotension. Other findings may include absent or depressed reflexes and erythematous or hemorrhagic blisters (primarily at pressure points). Following massive exposure to Phenobarbitone GPO, pulmonary edema, circulatory collapse with loss of peripheral vascular tone, cardiac arrest, and death may occur.
In extreme overdose, all electrical activity in the brain may cease, in which case a "flat"EEG normally equated with clinical death should not 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.
Complications such as pneumonia, pulmonary edema, cardiac arrhythmias, congestive heart failure, and renal failure may occur. Uremia may increase CNS sensitivity to barbiturates if renal function is impaired. Differential diagnosis should include hypoglycemia, head trauma, cerebrovascular accidents, convulsive states and diabetic coma.
Treatment
To obtain up-to-date information about the treatment of overdose, a good resource is your certified Regional Poison Control Center. Telephone numbers of certified poison control centers are listed in the Physicians' Desk Reference (PDR). In managing overdosage, consider the possibility of multiple drug overdoses, interaction among drugs, and unusual drug kinetics in your patient.
Protect the patient's airway and support ventilation and perfusion. Meticulously monitor and maintain, within acceptable limits, the patients vital signs, blood gases, serum electrolytes, etc. Absorption of drugs from the gastrointestinal tract may be decreased by giving activated charcoal, which, in many cases, is more effective then emesis or lavage; consider charcoal instead of or in addition to gastric emptying. Repeated doses of charcoal over time may hasten elimination of some drugs that have been absorbed. Safeguard the patient's airway when employing gastric emptying or charcoal.
Alkalinization of urine hastens Phenobarbitone GPO excretion, but dialysis and hemoperfusion are more effective and cause less troublesome alteration in electrolyte equilibrium. If the patient has chronically abused sedatives, withdrawal reactions may be manifest following acute overdose.
What should I avoid while taking Phenobarbitone GPO?
This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.
Drinking alcohol can increase some of the side effects of Phenobarbitone GPO.
Phenobarbitone GPO warnings
1. Habit forming: Phenobarbitone GPO may be habit forming. Tolerance, psychological and physical dependence may occur with continued use.. To minimize the possibility of overdosage or the development of dependence, the prescribing and dispensing of sedative-hypnotic barbiturates should be limited to the amount required for the interval until the next appointment. Abrupt cessation after prolonged use in the dependent person may result in withdrawal symptoms, including delirium, convulsions, and possibly death. Phenobarbitone GPO should be withdrawn gradually.
2. Acute or chronic pain: Caution should be exercised when Phenobarbitone GPO is administered to patients with acute or chronic pain, because paradoxical excitement could be induced or important symptoms could be masked. However, the use of Phenobarbitone GPO as a sedative in the postoperative surgical period and as an adjunct to cancer chemotherapy is well established.
3. Use in pregnancy: Phenobarbitone GPO can cause fetal damage when administered to a pregnant woman. Retrospective case-controlled studies have suggested a connection between the maternal consumption of Phenobarbitone GPO and higher than expected incidence of fetal abnormalities. Following oral administration, Phenobarbitone GPO readily crosses the placental barrier and is distributed throughout fetal tissues with highest concentrations found in the placenta, fetal liver, and brain.
Withdrawal symptoms occur in infants born to mothers who receive Phenobarbitone GPO throughout the last trimester of pregnancy. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.
4. Synergistic effects: The concomitant use of alcohol or other CNS depressants may produce additive CNS depressant effects.
What should I discuss with my healthcare provider before taking Phenobarbitone GPO?
Some medical conditions may interact with Phenobarbitone GPO elixir. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have depression, pain, breathing problems, suicidal tendencies, or are in shock
- if you have a history of substance abuse or dependence
Some MEDICINES MAY INTERACT with Phenobarbitone GPO elixir. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Ethanol, MAO inhibitors (eg, phenelzine), quinine, sodium oxybate (GHB), stiripentol, or valproic acid because side effects such as increased sedation and difficulty breathing may occur
- Ethanol, methoxyflurane, orsodium oxybate because the risk of their side effects may be increased by Phenobarbitone GPO elixir
- Anticoagulants (eg, warfarin), beta-blockers (eg, propranolol), clozapine, corticosteroids (eg, hydrocortisone), cyclosporine, doxorubicin, doxycycline, estrogens (eg, estradiol), imatinib, metronidazole, steroidal contraceptives (eg, birth control pills), theophylline, or voriconazolebecause their effectiveness may be decreased by Phenobarbitone GPO elixir
This may not be a complete list of all interactions that may occur. Ask your health care provider if Phenobarbitone GPO elixir may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
Phenobarbitone GPO precautions
General
Phenobarbitone GPO may be habit forming. Tolerance and psychological and physical dependence may occur with continuing use. Phenobarbitone GPO should be administered with caution, if at all, to patients who are mentally depressed, have suicidal tendencies, or a history of drug abuse. Elderly or debilitated patients may react to Phenobarbitone GPO with marked excitement, depression, and confusion. In some persons, Phenobarbitone GPO repeatedly produces excitement rather than depression.
In patients with hepatic damage, Phenobarbitone GPO should be administered with caution and initially reduced doses. Phenobarbitone GPO should not be administered to patients showing the premonitory signs of hepatic coma.
Laboratory Tests
Prolonged therapy with Phenobarbitone GPO should be accompanied by periodic laboratory evaluation of organ systems, including hematopoietic, renal, and hepatic systems
Carcinogenesis
Human-data: A retrospective study of 84 children with brain tumors matched to 73 normal controls and 78 cancer controls (malignant disease other than brain tumors) suggested an association between exposure to barbiturates prenatally and an increased incidence of brain tumors.
Pregnancy
Teratogenic effects: Pregnancy Category D.
Nonteratogenic effects: Reports of infants suffering from long- term Phenobarbitone GPO exposure in utero included the acute withdrawal syndrome of seizures and hyperirritability from birth to a delayed onset of up to 14 days.
Labor and Delivery
Hypnotic doses of Phenobarbitone GPO do not appear to significantly impair uterine activity during labor. Full anesthetic doses of Phenobarbitone GPO decrease the force and frequency of uterine contractions. Administration of sedative-hypnotic Phenobarbitone GPO to the mother during labor may result in respiratory depression in the newborn. Premature infants are particularly susceptible to the depressant effects of Phenobarbitone GPO. If Phenobarbitone GPO is used during labor and delivery, resuscitation equipment should be available.
Data are currently not available to evaluate the effect of Phenobarbitone GPO on the later growth, development, and functional maturation of the child.
Nursing Mothers
Caution should be exercised when Phenobarbitone GPO is administered to a nursing woman since small amounts of Phenobarbitone GPO are excreted in the milk.
What happens if I miss a dose of Phenobarbitone GPO?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
References
- DrugBank. "phenobarbital". http://www.drugbank.ca/drugs/DB01174 (accessed September 17, 2018).
- MeSH. "Excitatory Amino Acid Antagonists". https://www.ncbi.nlm.nih.gov/mesh/68... (accessed September 17, 2018).
- NITE-CMC. "5-Ethyl-5-phenyl-2,4,6(1H,3H,5H)-pyrimidinetrione; Phenobarbital: The chemical classification in this section was conducted by the Chemical Management Center (CMC) of Japan National Institute of Technology and Evaluation (NITE) in accordance with GHS Classification Guidance for the Japanese Government, and is intended to provide a reference for preparing GHS labelling and SDS for users.". http://www.safe.nite.go.jp/english/g... (accessed September 17, 2018).
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Information checked by Dr. Sachin Kumar, MD Pharmacology
