What Is Alfentanil?

It is a derivative of fentanyl and its hydrochloride is used medicinally. Mainly acting on opioid receptors, it is a short-acting analgesic with an analgesic intensity of 1/4 of fentanyl and a duration of action of 1/3. Onset of effect is fast, the peak is 1.5 to 2 minutes by intravenous injection, which is maintained for about 10 minutes, and the elimination half-life is 64 to 129 minutes. After a long-term infusion, the duration of its effect can be extended rapidly. Alfentanil is less lipophilic than fentanyl, but has a higher binding rate to plasma proteins, a smaller volume of distribution, conforms to the three-compartment model, and is excreted through the urine after inactivation of liver metabolism.

Drug Name: Alfentany
Alias: Alfenthani
Whether prescription drugs: prescription
Main indications: Induction and maintenance of short-term surgery anesthesia and general anesthesia
Dosage: Intravenous injection of 500 g or 8-20 g / kg

Adverse reactions: Nausea, vomiting, and stiffness of chest wall muscles
Main medication contraindications: This drug should not be used in combination with monoamine oxidase inhibitors
Dosage form: liquid
Athletes use with caution: Use with caution
Whether to include health insurance: Not included

Alfentanil Basic Information

Chinese name:

Chinese alias: Alfenthani

English name: Alfentanil

English alias: Alfentanilum; N- {1- [2- (4-ethyl-5-oxo-4,5-dihydro-tetrazol-1-yl) -ethyl] -4-methoxymethyl-piperidin-4-yl} -N -phenyl-propionamide; Rapifen; Alfentanil; Alfentanyl;

CAS number: 71195-58-9

Molecular formula: C ₂₁ H ₃₂ N ₆ O ₃

Molecular weight: 416.51700

Exact mass: 416.25400

PSA: 85.49000

LogP: 1.32180

Alfentanil physical and chemical properties

Density: 1.22 g / cm ³

Boiling point: 511.8ºC at 760 mmHg

Flash point: 263.3ºC ^[1]

Alfentanil drug-related instructions

Alfentanil classification

Neurological Drugs> Analgesics> Strong Analgesics

Alfentanil dosage form

1mg (1ml), 1mg (2ml), 2mg (10ml), 5mg (10ml), 500ug (5ml)-for pediatric use.

Alfentanil Pharmacological effects

It is an opioid receptor agonist and an ultra-short-term powerful analgesic. It has a fast onset of action and a short duration of action. The analgesic effect is greatest at 1 minute after injection, and the inhibitory effects on respiratory rate and oxygen supply through the alveoli generally last only a few minutes. Cardiovascular effects are similar to fentanyl.

Alfentanil Pharmacokinetics

The distribution process in vivo is a three-compartment model, especially when a single high-dose injection is used. A single dose of 100 g / kg is given intravenously to a patient. The distribution of t1 / 2 is 3.7min, the elimination of t1 / 2 is 1 to 2 hours, the apparent volume of distribution is 91ml / kg, and the clearance rate increases with age. And the redistribution from deep tissue decreases linearly. The plasma protein binding rate was 92%. The clearance rate of patients with cirrhosis was 1.6 ± 1.0ml / kg per minute, which was significantly lower than that of normal people. Almost all are metabolized by the liver, and the excretion dose from the urine of the original drug is less than 1%, and the liver excretion coefficient is 0.3 to 0.6. When using alfentanil in pregnant women, t1 / 2 and liver excretion coefficients were not significantly different from normal women.

Alfentanil Indication of Alfentanil

It is used for anesthesia induction and analgesia during anesthesia, anesthesia of coronary coronary artery bypass surgery.

Alfentanil Contraindications

1. People who are allergic to alfentanil and other opioids.

2. Those who obviously cannot tolerate morphine-like drugs.

Alfentany notes

1. (1) People with impaired liver and kidney function; (2) People with head injury or increased intracranial pressure; (3) People with lung disease or reduced respiratory reserve (because alfentanil can cause respiratory depression or suffocation) (4) pregnant women and babies.

2. Intravenous alfentanil can increase the incidence of muscle rigidity, which can be prevented by applying benzodiazepines and muscle relaxants in advance.

Alfentanil Adverse effects of Alfentanil

Like all opioid analgesics, it can cause respiratory depression or suffocation, which is dose-dependent. Large doses of respiratory depression can be countered by naloxone. Bradycardia can be countered by atropine. Myotonia can be caused during the induction of anesthesia, but it can be avoided by taking diazepam or giving muscle relaxants before anesthesia. Nausea and vomiting may occur after surgery, but the duration is short.

Alfentanil

1. The dosage is determined according to the operation time. The operation time is 10 ~ 30min, 30 ~ 60min and more than 60min. The intravenous injection amount is 20 ~ 40g / kg, 40 ~ 80g / kg, 80 ~ 150g / kg. When the dose is 120g / kg, it can cause sleep and analgesia, which can be changed to 1g / kg per minute; for surgery completed within 10min, intravenous injection is 7-15g / kg; for surgery over 10min, it can be every 10-15min Or as appropriate, 7 to 15 g / kg.

2. For those with automatic breathing, start with an intravenous injection of 500 g or 8 to 20 g / kg, and then add 250 g or 3 to 5 g / kg; for adults and children with assisted breathing, give 30 to 50 g / kg, and add 15 g / kg. .

Alfentanil Interaction with Alfentanil

1. Barbiturates, sedatives, opioids, inhaled anesthetics (enflurane, isoflurane) will enhance the effect of alfentanil.

2. Erythromycin, erythromycin / sulfaisoxazole, diltiazem, fluconazole can inhibit the cytochrome P4503A involved in alfentanil metabolism, thereby reducing the metabolism of alfentanil, making alfentanil The duration of action is longer and the toxicity is increased. The dose should be adjusted by monitoring the patient's response.

3. The combination of mesopital and thiopental and alfentanil can increase the respiratory depression.

4. Naltrexone competes with alfentanil for opioid receptors, causing opioid withdrawal symptoms.

5. Propofol can change the metabolism of alfentanil, thereby increasing the toxicity of alfentanil (such as respiratory depression, hypotension, bradycardia, etc.).

6. Rifabutin can induce cytochrome P450, accelerate the metabolism of alfentanil, and reduce the effect of alfentanil.

7. Long-term use of epinephrine beta blockers before surgery (such as acebutolol, betaxolol, bevanolol, bisoprolol, cateolol, cerilol, esmolol, In patients with labelolol, levobunolol, metoprolol, naldolol, and oxenololol, the use of alfentanil increases the incidence of bradycardia.

8. Alcohol will increase the metabolism of alfentanil in the liver, which will reduce the therapeutic effect of alfentanil.

Alfentany expert review

Clinically, it is not generally used for pain relief. As an intravenous general anesthetic, it has little effect on the cardiovascular system and generally does not affect blood pressure. ^[2]