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Pentobarbital Sodium – Uses

The pentobarbital-chlorpromazine-alcohol group scale (PCAG) provides a measure of sedation, the amphetamine (A or AMP) scale provides a measure of amphetamine-like effects, the benzedrine group scale (BG) also assesses amphetamine-like effects, the lysergic acid diethylamide (LSD) scale is sensitive to somatic and dysphoric changes, and finally, the morphine-benzedrine group (MBG) is often used to describe euphoria.

Pediatric Sedation and Analgesia

Barbiturates (Thiopental Methohexital, Methohexital and Pentobarbital)

Barbiturates are used to relax children younger than three years old to conduct diagnostic imaging. They are generally safe, but are not recommended for patients suffering from porphyria. The most serious side effects are breathing depression and apnea, as well as hypotension. Both occur more frequently when barbiturates are administered together with opiates or benzodiazepines.

Thiopental (Pentothal) is a fast-acting barbiturate, with an onset the action lasting between 30 and 60 seconds when administered intravenously, and five to eight minutes when it is administered in rectally. It can have an effects of 15 minutes when administered intravenously. However, it can last up to an hour when administered by rectally. Injecting it intravenously with dosages of 20-25 mg/kg, thiopental can be administered rectally to infants in a dose of 5-10 mg/kg. Thiopental’s most notable negative effect of reducing the pressure in the intracranial artery; it is thus particularly beneficial for patients with increased intracranial pressure can be a problem.

Methohexital (Brevital) can be described as an extremely-short-acting drug with an onset between 30 and 60 seconds and a time of effects between 5 and 10 mins. It’s twice more potent than thiopental and is able to be administered intravenously at a dosage in the range of 0.5 or 1.0 mg/kg to children who are older than 12 years old. It is not recommended to be given in children who are younger and is not advised for children with epilepsy of the temporal lobe since it may trigger seizures in this subset. Methohexital is not commonly used in the emergency department due to a single research (Zink 1991) of 102 patients where 22 patients suffered respiratory depression that required bag valve-mask support. Five of the patients suffered from intermittent apnea. When when combined with an analgesic medicine the risk of respiratory depression can be reduced by first administering an medication to reduce pain, and then gradually increasing methohexital until it has the required effectiveness.

Pentobarbital (Nembutal) is a beneficial barbiturate-based sedative used in longer radiologic procedures, such as magnetic resonance imaging or scans using positron emission. Its duration of effect that lasts between 3 and 5 mins when administered intravenously and a time of action of 30 to 45 mins. For infants and children older than 6 months old, it is administered intravenously in a dose between 1 and 3 mg/kg, and adjusted between 3 and 5 minutes until 100 mg, or intramuscularly at an amount of 2-6 mg/kg, with a maximum dose in 100 mg.

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Pentobarbital Sodium



Pentobarbital, a sodium salt, has been utilized to treat hypnosis and sedation for the short-term treatment of insomnia. Pentobarbital sodium is also utilized as a premedication for anesthetic procedures. Pentobarbital is approved by FDA to treat emergency cases of certain convulsive episodes that occur in the acute phase, e.g., those caused by status epilepticus meningitis, eclampsia and cholera, tetanus, as well as the toxic effects of strychnine and local anesthetics. The other indications for pentobarbital include treatment of nonfatal submersion and traumatic/nontraumatic raised intracranial pressure.


Intraperitoneal (IP) injection of pentobarbital can be used in research medicine as an anesthetic to small animals like rat and mouse. Pentobarbital is a powerful medication for treating seizures triggered by convulsive disorders which are often result from strychnine.

Dosage of Drugs

Short-Acting Barbiturates: Pentobarbital

Pentobarbital is water-soluble. If it is released into the air with an estimated vapor pressure of 3x 10-10mmHg (25 degC) It will exist in a particulate form in the atmosphere. As particulate pentobarbital it is removed from the atmosphere through dry or wet deposition. Pentobarbital is not prone to photolysis by sunlight since pentobarbital doesn’t contain any chromophores which absorb light with wavelengths higher than 290 nanometers. If pentobarbital does get released into soil with a pKa of 7.8 means that it exists as an anion that doesn’t absorb strongly to soils with organic carbon , clays or. Pentobarbital isn’t expected to break down from soils that are moist according to estimates of Henry’s law constant of 8.4 10-13 atm-cu-m mo-1. If it is released into water, pentobarbital isn’t expected to be able to adsorb to suspended sediments or other solids present in water based on estimates of Koc. The release of water-borne volatiles is not thought to be a major fate-related process, based on Henry’s law constant estimates. Pentobarbital is estimated to have a bioconcentration factor (BCF) that is 11, which suggests the potential for bioconcentration within aquatic organisms is very low. Pentobarbital does not contain functional groups that can hydrolyze easily and hydrolysis isn’t expected to be a significant environmental fate-related process.


The Status Epilepticus and Seizure Clusters

Seizure clusters are also known as acute repeated seizures or serial seizures, are seizures that are closely clustered, resulting in an increase in the frequency of seizures in comparison to baseline, typically lasting from minutes or a few days. Seizure clusters can include any kind of seizure, and can vary in intensity but, in general, they are completely recovered between seizures. Seizure clusters are more frequent in epilepsy patients who have drug resistance and, in particular, those who have epilepsy that is not symptomatic and remote epilepsy. Patients who have seizure clusters tend to be diagnosed with an epileptic history. Seizure clusters may be a precursor to long-lasting seizures, or even to status epilepticus. This progression could be anticipated for each patient according to their history of seizures. This can help determine the best course of treatment for seizures that occur in clusters. The milder clusters can be treated by oral doses of the benzodiazepines. However, more severe clusters, especially those that are which can lead to epilepticus or prolonged seizures could require alternative methods of treatment. Rectal diazepam is the only FDA-approved medication for use outside of hospitals by non-medical caregivers (Cereghino and al. 1998) up to the point that intranasal midazolam spray became available in the year of 2019 (Detyniecki and co. 2019,). Buccal midazolam is widely in use in Europe and other nations (Nakken and Lossius and Lossius, 2011,) but hasn’t been recognized by the FDA in the United States. Intranasal diazepam received approval from the US FDA in the year 2020. The effectiveness of intramuscular diazepam given by autoinjectors was confirmed in a blinded controlled study (Abou-Khalil and co. 2013, 2013) However, it didn’t result in FDA approbation or marketing. Other methods that were tested include buccal diazepam, staccato midazolam.

Status epilepticus has been previously defined as seizure activity that lasts for 30 minutes or recurrent seizures that do not recover between episodes. The 30-minute duration is the subject of debate because it could delay aggressive treatment, especially in cases where a longer duration could be anticipated in the absence of treatment. Research suggests that irreparable neuronal injury can occur after 20-30 mins of generalized convulsive state epilepticus (GCSE) (Fujikawa et al., 1996; Meldrum and Brierley 1973) Therefore, all efforts must be taken to stop seizures prior to. There is a large body of evidence that suggests that the tonic-clonic period bilaterally of generalized or focal seizures lasts no longer than two minutes (Jenssen and co. 2006a; Theodore and. 1994) however, it can develop to become status epilepticus. In the end, it is suggested that aggressive therapy for status epilepticus begin after five minutes of tonic-clonic activities (Lowenstein and. 1999). There is evidence to suggest that FIAS which last for more than 10 minutes could develop into status epilepticus (Jenssen and co. 2006a). In light of the above data, the ILAE classified status epilepticus as an illness “resulting due to the malfunction of the mechanisms that are responsible for stopping seizures or the induction of mechanisms that result in abnormally prolonged seizures (after time point t1) and may have lasting effects (after timing point 2)” (Trinka and co. (2015)). The time point for epilepticus status was 5 mins for bilateral tonic-clonic seizures. 10-15 minutes in the case of focal seizures and between 10 and 15 minutes for absence seizures.

Anesthesia and Analgesia


Pentobarbital is an oxybarbiturate derivative to barbituric acid. Pentobarbital may be used as an anesthetic, sedative, and anticonvulsant. The mechanism of action of pentobarbital is similar to propofol and benzodiazepines, because GABAA receptors become activated, resulting in increased GABA binding and the opening of transmembrane chloride channel leading to cellular hyperpolarization in the nervous system’s central region. The administration of pentobarbital causes the effects of dose-dependent hypnosis, sedation muscles relaxation, stimulation in the sensorimotor cortex as well as the reticular activating mechanism.

Like all GABAA agonists, pentobarbital exhibits minimal or no analgesic effects. Pentobarbital causes a dose-dependent respiratory depression that could require respiratory assistance (Peeters and co. 1988). When doses are higher pentobarbital has anticonvulsant and hypotensive properties. The cause of hypotension is vasodilation as well as decreased myocardial contractility and decreased cardiac output. These and other effects on the cardiovascular system depend on the route of administration. They are more likely to be less severe when using IP instead of IV. This is because the peak blood concentration of blood is achieved much more slowly than during IV administration, and the amount of drug absorbed into portal system is susceptible to destruction within the liver. Hypothermia is widespread and has been observed in Gerbils (Weinandy and co. 2005). The hypothermia most likely is a result of a decreased vasodilation and metabolism at the basal level. Sedation, as well as respiratory depression may occur when pentobarbital is used together with tranquilizers, benzodiazepines or alpha2-agonists, opioids propofol, inhalants, and anesthetic agents. The animals receiving pentobarbital must receive oxygen-supplementation or monitored using pulse oxygen oximetry. The general anesthetic dosages could require support for respiratory or endotracheal intubation.

If pentobarbital is given an additional source of heat is recommended to be applied to the animal throughout the period of surgery and maintained until complete recovery in order to avoid hypothermia. Pentobarbital is administered intraperitoneally or via intravenous injection. In the case of general anesthetic, it is administered as an Bolus (Borkowski and co., 1990). 1990) or as a CRI. Commercial products usually contain propylene glycol that may cause pain after injection and thrombophlebitis. This is why the intramuscular and subcutaneous methods of injection aren’t suggested.

Status Epilepticus


Pentobarbital (or thiopental) can be a complete treatment for SE with refractory. Short-acting barbiturates can be absorbed quickly however, they need intensive treatment. Doses that range from 3 to 5 mg/kg, followed by infusions of 1 or 3 mg/kg/hour is typical. there are studies that suggest that patients require at minimum 3.5 mg/kg/hour. Effectiveness is measured as the effect on the electroencephalogram, with an attempt to eliminate seizures or aim for a burst suppression or flat record; most reviewers seek a burst suppression pattern. Pentobarbital’s half-life is around 20 hours, however it could be extended in higher doses. Therefore, prolonged coma following treatment with pentobarbital is not due to the “burnt out” brain prior to the medication having taken time to disappear. The levels of pentobarbital are more helpful to determine the residual toxicity of a drug than in assessing the therapeutic effect.

All SE are able to be controlled by appropriate doses of pentobarbital. However, hypotension is quite common. Typically it is a matter of volume replacement, and small doses of vasopressors will suffice. The function of the myocardium and temperature regulation may be affected. A majority of studies on pentobarbital have shown a high rate of mortality that is often attributed to serious underlying conditions that cause SE that are refractory enough to require pentobarbital. The benefit of pentobarbital aside from its constant efficacy when administered in large enough doses, is decrease in cerebral metabolism as well as blood flow. It is also simple to alter. The ideal duration for barbiturate-induced compa hasn’t been determined. The recommended duration is between 4 and 72 hours. At least 24 hours can be helpful. Patients are likely to be taking therapeutic doses of two other anticonvulsants prior to pentobarbital withdrawal.


Beta-adrenoceptor antagonists

Pentobarbital improves the clearance and lowers the plasma concentrations of certain beta-blockers, including alprenolol (100,101), with the loss of beta-blockade. In healthy subjects, pentobarbital 100 mg decreased the levels of plasma of oral alprenolol at steady state 200 mg/day for 10 consecutive days and its metabolite, 4-hydroxyalprenolol without affecting half-lives.

In eight healthy individuals, pentobarbital 100 mg/day over 10 days decreased the AUC for metoprolol by 32% with significant variation between individuals (2-46 percent).



Pentobarbital is one of the barbiturates that can be capable of causing profound amnesia, hypnosis, sedation and anticonvulsant action in a dose-dependent manner. It does not possess any inherent analgesic properties. If it is carefully titrated IV it is sedative within 5 minutes, with the duration of 30-40 minutes.


Pentobarbital is an acid derivative of barbituric, is widely used to treat anesthesia of nonhuman primates however, it can cause significant respiratory and cardiovascular depletion and the effects are in a cumulative manner. The recovery from pentobarbital takes a long time and is often associated with an involuntary exuberance and the occurrence of prolonged ataxia. Pentobarbital is more effective replaced by other medications, excluding last resort (nonrecovery) procedures, such as perfusion-fixation, where the depressant effects of this medication are considered not to be important. Thiopental can be a helpful induction agent. However, maintaining of anesthesia through continuous infusion or administering successive doses leads to long recovery times and it is best replaced by alphaxalone or propofol.