Epistatus: Uses, Dosage & Side Effects

What Is Epistatus and What Is It Used For?

Epistatus contains the active substance midazolam, which belongs to a class of medications known as benzodiazepines. Benzodiazepines are among the most widely used medications in neurology and emergency medicine due to their rapid-onset anticonvulsant, sedative, anxiolytic, and muscle relaxant properties. Midazolam has been recognized by the World Health Organization as an essential medicine for the treatment of status epilepticus in children, and it is included on the WHO Model List of Essential Medicines for Children.

The primary indication for Epistatus is the emergency treatment of prolonged, acute, convulsive seizures in infants (aged 3–6 months, hospital use only), toddlers (6 months to under 5 years), children (5 to under 10 years), and adolescents (10 to under 18 years). A seizure is considered prolonged when it lasts for more than 5 minutes, at which point the likelihood of spontaneous cessation decreases significantly and the risk of progressing to established status epilepticus increases. Status epilepticus is a medical emergency defined as a seizure lasting 30 minutes or longer (or repeated seizures without recovery of consciousness between them), which can lead to permanent brain injury and has a mortality rate of 3–20% depending on the underlying cause, duration, and patient age.

Midazolam works by enhancing the activity of gamma-aminobutyric acid (GABA) in the central nervous system. GABA is the principal inhibitory neurotransmitter in the brain, and when it binds to its receptor (the GABA-A receptor), it opens chloride ion channels that allow negatively charged chloride ions to enter the neuron, making it less excitable. Midazolam binds to a specific site on the GABA-A receptor complex (the benzodiazepine binding site) and increases the frequency with which the chloride channel opens in response to GABA. This enhanced inhibitory effect rapidly suppresses the abnormal, excessive neuronal firing that characterizes epileptic seizures.

Unlike intravenous formulations of midazolam that require venous access and medical professional administration, Epistatus is specifically designed for oromucosal (buccal) delivery. The solution is provided in pre-filled oral syringes and is administered by slowly squirting it into the space between the gum and the inner cheek (the buccal cavity). The buccal mucosa has a rich blood supply and relatively thin epithelium, allowing midazolam to be absorbed directly into the systemic circulation without undergoing significant first-pass metabolism in the liver. This results in a bioavailability of approximately 75% and onset of action typically within 5–10 minutes. The buccal route offers several advantages over the rectal route (which was the traditional community rescue treatment using diazepam): it is easier to administer during a seizure, more socially dignified for older children and adolescents, and does not require the patient to be undressed.

The clinical effectiveness of buccal midazolam has been demonstrated in multiple randomized controlled trials. The landmark study by McIntyre et al. (2005), published in The Lancet, compared buccal midazolam with rectal diazepam in 219 episodes of prolonged seizures in children presenting to emergency departments. Buccal midazolam was successful in terminating seizures in 56% of episodes compared with 27% for rectal diazepam (p=0.002), with no significant difference in adverse effects. A subsequent Cochrane systematic review confirmed that buccal midazolam is at least as effective as rectal diazepam and may be superior in the community setting, where the ease of administration leads to faster drug delivery and earlier seizure cessation.

What Should You Know Before Taking Epistatus?

Contraindications

Epistatus must not be used in the following situations:

• Hypersensitivity: Known allergy to midazolam, other benzodiazepines, or any of the excipients in the formulation. Symptoms of an allergic reaction may include skin rash, itching, swelling of the face or throat, and difficulty breathing.
• Severe respiratory insufficiency: Patients with significantly impaired respiratory function are at increased risk of respiratory depression with benzodiazepine use. However, in the context of a life-threatening prolonged seizure, the benefit of stopping the seizure generally outweighs this risk.
• Myasthenia gravis: Benzodiazepines may exacerbate the muscle weakness characteristic of this neuromuscular condition due to their muscle relaxant properties.
• Age under 3 months: The safety and efficacy of Epistatus have not been established in neonates and infants under 3 months of age. The blood-brain barrier in very young infants is less mature, potentially resulting in enhanced central nervous system effects.

Warnings and Precautions

Before using Epistatus, the prescribing physician should discuss the following precautions with caregivers:

• Respiratory monitoring: After administration, caregivers should monitor the patient's breathing closely. The risk of respiratory depression is higher in patients who are already receiving regular benzodiazepines (e.g., clobazam, clonazepam) as part of their antiepileptic therapy, or in patients with pre-existing respiratory conditions.
• Paradoxical reactions: In rare cases, particularly in children and elderly patients, midazolam may cause paradoxical reactions including restlessness, agitation, irritability, involuntary movements, hyperactivity, hostility, rage reactions, and aggression. If such a reaction occurs, the use of midazolam should be reconsidered in future seizure management plans.
• Hepatic impairment: Midazolam is primarily metabolized in the liver by the cytochrome P450 enzyme CYP3A4. Patients with significant liver disease may have prolonged sedation due to decreased drug clearance. Dosage adjustments may be necessary.
• Renal impairment: Although midazolam is primarily hepatically cleared, its active metabolite (alpha-hydroxymidazolam) is renally excreted. Patients with severe kidney disease may experience prolonged effects.
• Training requirement: Caregivers must be properly trained by a healthcare professional in the correct administration technique before the first use of Epistatus. This includes understanding when to administer the medication, how to use the pre-filled syringe, positioning of the patient, monitoring after administration, and when to seek emergency medical help.

Pregnancy and Breastfeeding

Epistatus is indicated for use in children and adolescents under 18 years of age, so pregnancy and breastfeeding considerations are generally not directly applicable to the target patient population. However, healthcare providers should be aware that midazolam as a substance class crosses the placenta and is excreted in breast milk. If Epistatus were to be used off-label in a pregnant or breastfeeding patient, the potential benefits of treating a life-threatening seizure would need to be weighed against the potential risks to the fetus or infant. Benzodiazepines administered during pregnancy, particularly in the third trimester, may cause neonatal withdrawal symptoms (floppy infant syndrome) or respiratory depression in the newborn.

Use in Different Age Groups

Epistatus is available in four strength-specific formulations to allow appropriate dosing across the pediatric age range. The dose is determined by the patient's age group, not by body weight, to simplify administration during an emergency:

• Infants 3–6 months (hospital use only): 2.5 mg. This age group should only receive Epistatus in a hospital or clinical setting where respiratory monitoring and resuscitation equipment are immediately available.
• Infants and toddlers 6 months to under 1 year: 2.5 mg
• Toddlers 1 year to under 5 years: 5 mg
• Children 5 years to under 10 years: 7.5 mg
• Adolescents 10 years to under 18 years: 10 mg

How Does Epistatus Interact with Other Drugs?

Understanding drug interactions is particularly important for Epistatus because many patients with epilepsy are already taking one or more antiepileptic drugs (AEDs), some of which affect the same metabolic pathways as midazolam. Since Epistatus is used as an emergency rescue medication rather than a regular daily treatment, interactions primarily affect the intensity and duration of its effects rather than chronic exposure levels.

Midazolam is extensively metabolized in the liver and intestinal wall by the cytochrome P450 3A4 (CYP3A4) enzyme system. Drugs that inhibit CYP3A4 will increase plasma concentrations of midazolam, potentially leading to enhanced and prolonged sedation, while drugs that induce CYP3A4 will decrease plasma concentrations, potentially reducing the effectiveness of Epistatus.

Major Interactions

Interactions with Antiepileptic Drugs

Many children using Epistatus will already be taking antiepileptic medications as maintenance therapy. Several of these have clinically relevant interactions with midazolam:

• Carbamazepine and Phenytoin: Both are potent CYP3A4 inducers that can reduce midazolam plasma concentrations by 50–90%. Patients taking these medications chronically may have a reduced response to Epistatus, potentially requiring closer monitoring and earlier involvement of emergency medical services.
• Valproic acid (Sodium valproate): Valproate may slightly increase midazolam levels by displacing it from plasma protein binding sites. This interaction is generally of minor clinical significance but may contribute to enhanced sedation.
• Clobazam and Clonazepam: These are benzodiazepines used as maintenance antiepileptic therapy. Concurrent use with Epistatus produces additive CNS depressant effects, increasing the risk of prolonged sedation and respiratory depression. Caregivers should inform emergency medical personnel of all benzodiazepines the patient is taking.
• Stiripentol: A CYP3A4 inhibitor used as adjunctive therapy in Dravet syndrome. Co-administration may increase midazolam levels and prolong its effects.
• Cannabidiol (Epidyolex): Cannabidiol is a CYP3A4 inhibitor that may increase midazolam exposure. Patients receiving cannabidiol should be monitored for enhanced sedation following Epistatus administration.

What Is the Correct Dosage of Epistatus?

Epistatus is supplied as a ready-to-use, pre-filled oral syringe containing a single dose of midazolam oromucosal solution. The use of age-based dosing rather than weight-based dosing is a deliberate design choice to minimize the risk of dosing errors during the stressful and time-critical situation of an ongoing seizure. Each syringe is color-coded and clearly labeled with the corresponding age range to further reduce the risk of errors.

How to Administer Epistatus

Correct administration technique is critical for the medication to work effectively. Caregivers should practice the technique with their healthcare provider before the first actual use. The following steps should be followed:

1. Confirm the seizure is prolonged: Wait until the seizure has lasted for the duration specified in the individual care plan (usually 5 minutes). Time the seizure using a clock or phone.
2. Position the patient safely: If possible, place the patient on their side (recovery position) to prevent aspiration. Do not restrain the patient or put anything in their mouth.
3. Prepare the syringe: Remove the cap from the pre-filled oral syringe. Do not attach a needle.
4. Administer the solution: Gently insert the tip of the syringe between the gum and the inner cheek. Slowly push the plunger to deliver approximately half the dose on one side. If possible, administer the remaining half on the other side of the mouth.
5. Monitor and wait: Note the time of administration. Monitor the patient's breathing closely. Wait for up to 10 minutes for the seizure to stop.
6. Seek emergency help if needed: If the seizure has not stopped within 10 minutes of administration, or if the patient develops breathing difficulties, call emergency services immediately.

Missed Dose

The concept of a “missed dose” does not apply to Epistatus in the traditional sense, as it is an emergency rescue medication used only during active seizures rather than a scheduled daily treatment. If a caregiver was unable to administer Epistatus during a seizure (for example, because the medication was not available at the time), they should call emergency services immediately and report the situation. After the episode has resolved, the prescribing physician should be contacted to discuss whether any adjustments to the seizure management plan are needed, and to ensure an adequate supply of Epistatus is available for future emergencies.

Overdose

An overdose of midazolam can cause excessive central nervous system depression, manifesting as severe drowsiness, confusion, impaired coordination, diminished reflexes, respiratory depression, apnea (cessation of breathing), hypotension (low blood pressure), and in severe cases, coma. Respiratory depression is the most dangerous consequence of midazolam overdose and can be fatal if untreated.

If an overdose is suspected, call emergency services immediately. The specific antidote for benzodiazepine overdose is flumazenil (Anexate), a competitive antagonist at the benzodiazepine binding site on the GABA-A receptor. Flumazenil is administered intravenously in a hospital setting and rapidly reverses the sedative and respiratory depressant effects of midazolam. However, flumazenil must be used with caution in patients with epilepsy, as it can provoke seizures. Supportive care, including assisted ventilation and cardiovascular monitoring, should be provided as needed.

What Are the Side Effects of Epistatus?

Like all medicines, Epistatus can cause side effects, although not everybody gets them. Many of the side effects associated with midazolam are extensions of its pharmacological action on the central nervous system and are generally expected in the context of treating an acute seizure. The side effect profile of buccal midazolam has been well characterized through clinical trials, post-marketing surveillance, and decades of clinical experience with midazolam in various formulations.

It is important for caregivers to understand that the effects of Epistatus (such as drowsiness and sedation) can overlap with the postictal state—the recovery period after a seizure during which patients typically experience confusion, fatigue, headache, and sleepiness. This makes it difficult to distinguish drug side effects from the natural aftermath of the seizure itself. Any concerns about a patient's condition after Epistatus administration should be discussed with a healthcare professional.

Paradoxical Reactions in Children

Paradoxical reactions deserve special mention because they are more commonly observed in children than in adults. Instead of the expected sedation and calming effect, the patient may become agitated, restless, irritable, aggressive, or even hostile after receiving midazolam. These reactions are thought to occur due to the complex pharmacology of GABA-A receptor subtypes in the developing brain. The incidence of paradoxical reactions is estimated at 1–5% in the pediatric population. If a paradoxical reaction occurs, the prescribing physician should be informed, and the seizure management plan may need to be revised to include an alternative rescue medication.

Respiratory Depression

Respiratory depression is the most clinically significant adverse effect of midazolam and the primary safety concern with Epistatus. The risk is dose-dependent and is increased in the following circumstances:

• Concurrent use of other CNS depressants (opioids, barbiturates, other benzodiazepines, sedating antihistamines)
• Pre-existing respiratory disease or obstructive airway conditions
• Very young infants (particularly those under 6 months, for whom hospital-only administration is recommended)
• Hepatic impairment leading to reduced drug clearance
• Administration of doses higher than recommended

In clinical practice, serious respiratory depression requiring medical intervention following buccal midazolam in the community setting is rare. A large retrospective study published in Archives of Disease in Childhood (2009) analyzed over 1,000 community administrations of buccal midazolam and found that the rate of significant respiratory events requiring intervention was less than 1%. Nevertheless, caregivers must be trained to recognize signs of respiratory depression (very slow or shallow breathing, blue discoloration of lips or fingertips, unresponsiveness) and to seek immediate medical help if these occur.

How Should You Store Epistatus?

Proper storage of Epistatus is essential to ensure the medication remains effective when needed in an emergency. Midazolam oromucosal solution is a relatively stable pharmaceutical preparation, but it can degrade if exposed to high temperatures, direct sunlight, or moisture for prolonged periods.

The following storage guidelines should be followed:

• Temperature: Store below 25°C (77°F). Do not refrigerate or freeze. Brief exposure to higher temperatures during travel (e.g., in a car during summer) should be minimized. Consider using an insulated pouch if ambient temperatures exceed 25°C.
• Light protection: Keep the pre-filled syringes in their original packaging (outer carton) to protect from light. Midazolam is sensitive to ultraviolet light, which can accelerate chemical degradation.
• Accessibility: While Epistatus should be kept out of the reach of children to prevent accidental ingestion, it must also be readily accessible to the trained caregiver in an emergency. Many families keep the medication in a designated, clearly labeled emergency kit that is stored in a secure but quickly accessible location.
• Expiry date: Check the expiry date printed on the packaging at least every 3 months. Replace the medication before it expires. Do not use Epistatus after the expiry date, as the potency of the active ingredient may have decreased, potentially reducing its effectiveness in stopping a seizure.
• Travel: Always carry Epistatus when traveling with a child who has been prescribed it. Keep a copy of the prescription and the individual seizure management plan with the medication. Inform airlines or other transport providers if necessary.
• Disposal: Do not dispose of expired or unused Epistatus in household waste or down the drain. Return it to a pharmacy for safe disposal in accordance with local regulations.

What Does Epistatus Contain?

Each pre-filled oral syringe of Epistatus contains midazolam as the active substance, formulated as midazolam maleate (the maleate salt form improves the aqueous solubility and stability of the solution). The four available strengths correspond to the following midazolam content:

Excipients (Inactive Ingredients)

In addition to the active ingredient, Epistatus contains the following excipients that are necessary for the formulation's stability, pH balance, and palatability:

• Sodium chloride: Used to adjust the tonicity (osmolality) of the solution to make it compatible with the buccal mucosa.
• Hydrochloric acid: Used to adjust the pH of the solution to the optimal range for midazolam stability and buccal absorption.
• Sodium hydroxide: Used in combination with hydrochloric acid for precise pH adjustment.
• Purified water: The solvent base of the formulation.

Epistatus does not contain lactose, gluten, preservatives, or colorants. The solution is clear to slightly yellow in color. The formulation has been designed to have a relatively simple excipient profile to minimize the risk of allergic or sensitivity reactions, particularly in the pediatric population where excipient sensitivities are a consideration.

The pre-filled oral syringes are made of polypropylene with a low-density polyethylene plunger, both of which are latex-free. This is an important consideration for patients with latex allergies. The syringe has a Luer-lock tip that is not compatible with intravenous needles, reducing the risk of inadvertent intravenous administration.