Pharmacology and Clinical Use of Apaurin (Diazepam) in EMS

Introduction Apaurin (diazepam) is a long-acting benzodiazepine with marked anxiolytic, anticonvulsant, sedative, and muscle-relaxant effects. In emergency medicine it’s the first-line drug for acute epileptic seizures (status epilepticus), febrile seizures in children, and acute agitation or anxiety states.

1. Drug Identification

• Active substance: Diazepamum.
• Trade names in Slovakia: Apaurin (injection), Diazepam (tablets / rectal tube).
• ATC classification: N05BA01 (Anxiolytics, benzodiazepine derivatives).
• Dosage form in EMS:
  • Injection solution 10 mg/2 ml.
  • Rectal tube 5 mg or 10 mg (mainly for pediatrics).
• Pharmacological group: Benzodiazepine.

2. Mechanism of Action (Pharmacodynamics) Diazepam indirectly stimulates the brain’s inhibitory neurotransmitter system:

• GABA-A receptor binding: Diazepam binds to a specific benzodiazepine binding site on the gamma-aminobutyric acid (GABA) receptor.
• Potentiation of inhibition: Increases the receptor’s affinity for GABA itself, leading to more frequent opening of chloride channels.
• Hyperpolarization: Chloride ion influx into the neuron hyperpolarizes it, making it less excitable.
• Result: Suppression of the spread of electrical discharges in the brain (stopping seizures) and overall CNS depression.

3. Hemodynamic Effects – IN DETAIL

• Blood pressure: At standard doses, mild drop in systolic pressure from general sedation. Hypotension risk rises with rapid IV administration or combination with other depressant substances (alcohol, opioids).
• Heart rate: Mild decrease (bradycardia) secondary to sedation.
• Respiratory system: Critical risk of respiratory center depression! Diazepam reduces CO2 sensitivity and respiratory rate. Apnea risk is high, especially with a rapid IV bolus.

4. Pharmacokinetics (from a Paramedic’s Perspective)

• Routes of administration:
  • IV: Fastest effect for seizures (give slowly into a large vein).
  • PR (rectal): Preferred in children or when IV access isn’t possible.
  • IM: Not recommended in EMS (slow, unpredictable absorption, tissue irritation).
• Onset of action: IV administration: 1–3 minutes; rectal: 5–10 minutes.
• Peak effect: IV: nearly immediate.
• Duration of effect: 15–60 minutes (redistribution from brain to fatty tissue), but elimination half-life is very long (20–50 hours).
• Metabolism: Hepatic. Has active metabolites (nordiazepam).

5. Indications in Prehospital Practice

1. Status epilepticus / acute seizures: Of any origin (metabolic, traumatic, febrile).
2. Acute anxiety and agitation: Panic attacks, acute stress reactions.
3. Sedation before procedures: E.g., before electrical cardioversion (if midazolam isn’t available).
4. Muscle spasms: Tetanus or acute painful muscle contractures.
5. Withdrawal syndrome: Delirium tremens in alcoholism.

6. Dosing in EMS

• Adult (seizures): 10 mg IV (slowly, approximately 2–5 mg per minute). May be repeated after 10 minutes up to a total dose of 30 mg.
• Pediatrics (rectal): Children under 15 kg: 5 mg; over 15 kg: 10 mg.
• Pediatrics (IV): 0.2–0.3 mg/kg body weight.
• Scope of practice: Physician (RLP). A basic-crew paramedic (RZP) — administering diazepam (particularly rectally) is a standard competency for seizure management in Slovakia.

7. Contraindications

• Absolute: Myasthenia gravis (risk of total muscle weakness), severe respiratory insufficiency, hypersensitivity, acute intoxication with depressant substances (alcohol).
• Relative: Shock states, elderly patients (fall and confusion risk), angle-closure glaucoma.

8. Adverse Effects

• Respiratory: Hypoventilation, apnea.
• Neurological: Somnolence, ataxia (coordination impairment), paradoxical excitation (particularly in children and seniors — agitation instead of sedation).
• Local: Thrombophlebitis with IV administration (the solution is irritating; dilute or flush).

9. Drug Interactions in EMS

• Opioids (fentanyl, morphine): Significant potentiation of respiratory depression.
• Alcohol: An extremely dangerous combination (risk of fatal CNS and respiratory depression).
• Muscle relaxants: Amplified effect.

10. Specifics in Emergency Medicine

• Error #1: A rapid bolus. Giving 10 mg IV over 5 seconds almost always causes apnea. Monitor breathing!
• Error #2: Dilution. Apaurin can precipitate (cloud) when mixed with normal saline in a syringe. It’s recommended to give it undiluted into a running infusion line.
• Safety: When giving it IV, always have a bag-valve-mask and airway equipment ready.

11. Red Flags

1. Bradypnea: If respiratory rate drops below 8–10/min, assist ventilation.
2. Hypotension: If BP drops significantly, consider positioning and fluids.
3. Paradoxical reaction: If the patient becomes more aggressive after administration, do not give further benzodiazepine doses.

12. Antidote

• Flumazenil (Anexate): A specific antagonist that reverses the benzodiazepine effect (covered in a separate article).

13. Practical Field Scenario Situation: A 30-year-old man found on the street in tonic-clonic seizures. Seizures have continued uninterrupted for 5 minutes. Status: Facial cyanosis, foaming at the mouth, GCS 3. Decision-making:

1. Head protection, oxygen therapy.
2. Secure IV access (if not possible, 10 mg PR).
3. Apaurin 10 mg IV, slowly (over 2 minutes).
4. Monitor seizure cessation and return of spontaneous breathing. Hemodynamic rationale: Seizure activity extremely depletes oxygen reserves. Apaurin stops the seizures, allowing reoxygenation, but we must watch that we don’t cause apnea with the drug itself.

14. Practical Summary – 5 Key Points

1. Slowly into the vein: At least 2 minutes for 10 mg.
2. Breathing is priority: Benzodiazepines and apnea go hand in hand.
3. Rectal for children: Fast and safe at home.
4. Don’t dilute with saline: Give it directly to avoid drug precipitation.
5. Status epilepticus: Diazepam is your first soldier on the field.

Professional Sources and Literature:

1. SmPC (Summary of Product Characteristics) – Apaurin injection solution 10 mg/2 ml.
2. Slovak Ministry of Health guidance on the treatment of status epilepticus.
3. Dobiáš, V. et al.: Emergency Healthcare. Osveta, 2021.
4. Lüllmann, H. et al.: Pharmacology and Toxicology. Grada, 2014. (Chapter: Psychopharmaceuticals.)
5. ILCOR / ERC Guidelines: Recommendations for field seizure management.