RAPIFEN® 2 ML SOLUTION FOR INJECTION AND INFUSION
Alfentanil hydrochloride 0,5 mg
What it does
Alfentanil is a strong pain-relieving medication belonging to the opioid class, commonly used in medical settings.
Commonly used for: severe pain relief, pain management during surgery
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
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Answers come only from this medicine's registration record, BNF monograph and interaction data - not medical advice.
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Sourcing - Kenya onlyRegistration & product details
Source: Botswana Medicines Regulatory Authority · fetched 2026-04-15 20:42:56 · updated 2026-10-20 04:32:03
Drug Interactions
92Pharmacodynamic Warnings
Alfentanil appears in TABLE 6: Drugs that cause bradycardia
Alfentanil appears in TABLE 11: Drugs with CNS depressant effects
Severe (10)
Alfentanil - decreases concentration
Brigatinib potentially decreases the concentration of opioids (alfentanil, fentanyl). Avoid. Also see TABLE 6 p. 1518
Alfentanil - increases exposure
Ceritinib is predicted to increase the exposure to opioids (alfentanil, fentanyl). Avoid. Theoretical → Also see TABLE 6 p. 1518
Alfentanil - decreases exposure
Lorlatinib is predicted to decrease the exposure to opioids (alfentanil, fentanyl). Avoid.
Alfentanil - increases exposure
Selpercatinib is predicted to increase the exposure to opioids (alfentanil, buprenorphine). Avoid.
Opioids - decreases concentration
Brigatinib potentially decreases the concentration of opioids (alfentanil, fentanyl). Avoid. Also see TABLE 6 p. 1518
Opioids - increases exposure
Ceritinib is predicted to increase the exposure to opioids (alfentanil, fentanyl). Avoid. Theoretical → Also see TABLE 6 p. 1518
Opioids - increases risk of cnstoxicity
Ritonavir increases the risk of CNS toxicity when given with opioids (pethidine). Avoid.
Opioids - decreases exposure
Lorlatinib is predicted to decrease the exposure to opioids (alfentanil, fentanyl). Avoid.
Opioids - increases risk of adverse effects
Selegiline increases the risk of adverse effects when given with opioids (pethidine). Avoid. Also see TABLE 13 p. 1520
Opioids - increases exposure
Selpercatinib is predicted to increase the exposure to opioids (alfentanil, buprenorphine). Avoid.
Moderate (53)
Alfentanil - increases exposure
Dronedaroneispredictedtoincreasetheexposuretoopioids (alfentanil,buprenorphine,fentanyl,oxycodone).Monitorand adjustdose.oStudy →AlsoseeTABLE6p.1518
Alfentanil - increases exposure
Miconazole is predicted to increase the exposure to opioids (alfentanil). Use with caution and adjust dose.
Alfentanil - increases exposure
Antifungals, azoles (fluconazole, isavuconazole, posaconazole) are predicted to increase the exposure to opioids (alfentanil, buprenorphine, fentanyl, oxycodone). Monitor and adjust dose.
Alfentanil - increases exposure
Berotralstat is predicted to increase the exposure to opioids (alfentanil, fentanyl). Monitor and adjust dose.
Alfentanil - decreases exposure
Cenobamate is predicted to decrease the exposure to opioids (alfentanil). Adjust dose. Also see TABLE 11 p. 1519
Unknown (29)
Alfentanil - increases exposure
Asciminibispredictedtoincreasetheexposuretoopioids (alfentanil).rTheoretical
Alfentanil - increases exposure
Bulevirtideispredictedtoincreasetheexposuretoopioids (alfentanil).oTheoretical
Alfentanil - increases exposure
Entrectinib is predicted to increase the exposure to opioids (alfentanil, fentanyl).
Alfentanil - increases exposure
Mifepristoneispredictedtoincreasetheexposuretoopioids (alfentanil).rTheoretical
Alfentanil - decreases exposure
Mitotane is predicted to decrease the exposure to opioids (alfentanil, fentanyl).
Data from BNF 85 (British National Formulary). This is not a substitute for professional medical advice. Matched via: exact
About this medicine
Alfentanil is a strong pain-relieving medication belonging to the opioid class, commonly used in medical settings.
What it treats
- severe pain relief
- pain management during surgery
How it works
Alfentanil works by blocking pain signals in the brain, helping to reduce the sensation of pain.
Who it's for
It is for patients experiencing severe pain, especially those undergoing surgery.
Drug class
Opioids
Cautions
- • Be careful if you are taking medications that slow down your heart rate.
- • Avoid using it with drugs that can make you feel sleepy or less alert.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: Alfentanil
BNF-referencedAlfentanil is a potent synthetic opioid analgesic used primarily for its analgesic properties during surgical procedures and in assisted ventilation. It is particularly effective for short-duration procedures due to its rapid onset and short duration of action.
Indications
- Peri-operative analgesia
- Assisted ventilation
- Enhancement of anaesthesia during short procedures
Dosage
Children: Neonate: Initially 5–20 micrograms/kg, supplemental doses up to 10 micrograms/kg. Child: Initially 10–20 micrograms/kg, supplemental doses up to 10 micrograms/kg; for maintenance, 30–60 micrograms/kg/hour via intravenous infusion.
Adults: For intravenous injection, initial bolus of 50-100 micrograms/kg over 30 seconds; for maintenance, 30-60 micrograms/kg/hour via intravenous infusion. Doses should be adjusted based on clinical response and patient condition.
Mechanism of action
Alfentanil binds to mu-opioid receptors in the central nervous system, resulting in analgesia and sedation. It modulates pain perception and response by inhibiting the release of neurotransmitters involved in pain pathways.
Pharmacodynamics
Alfentanil exhibits rapid onset of action, providing analgesia within minutes of administration, with effects generally lasting for a shorter duration compared to other opioids. Its potency allows for lower doses to achieve desired analgesic effects.
Pharmacokinetics
Alfentanil is rapidly metabolized in the liver and has a shorter half-life compared to traditional opioids, making it suitable for use in situations requiring quick recovery from anesthesia. Clearance may be increased in children, and its half-life can be prolonged in neonates.
Contra-indications
- Hypersensitivity to alfentanil or any of its components
- Severe respiratory depression
- Acute or severe bronchial asthma
- Paralytic ileus
- Concurrent use with monoamine oxidase inhibitors (MAOIs)
Adverse effects
- Respiratory depression
- Drowsiness
- Nausea
- Vomiting
- Hypotension
- Bradycardia
- Constipation
Interactions
- Brigatinib: Severe (decreases concentration)
- Ceritinib: Severe (increases exposure)
- Lorlatinib: Severe (decreases exposure)
- Selpercatinib: Severe (increases exposure)
- Dronedarone: Moderate (increases exposure)
- Miconazole: Moderate (increases exposure)
- Antifungals, azoles: Moderate (increases exposure)
- Berotralstat: Moderate (increases exposure)
- Cenobamate: Moderate (decreases exposure)
- Cobicistat: Moderate (increases exposure)
Precautions
- Use with caution in patients with renal impairment
- Monitor for respiratory depression, especially postoperatively
- Adjust dose in obese patients based on ideal body weight
Pregnancy
Use only if clearly needed; potential risks should be balanced against benefits.
Breast-feeding
Caution is advised; monitor infant for sedation.
Storage
Store below 25°C. Protect from light.
Formulations
- Alfentanil 5 mg/1 ml solution for injection ampoules
- Alfentanil 1 mg/2 ml solution for injection ampoules
- Alfentanil 25 mg/50 ml solution for injection vials
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
Molecular reference: Alfentanil
PubChem CID 51263Molecular formula: C21H32N6O3
Mechanism of action
Opiate receptors are coupled with G-protein receptors and function as both positive and negative regulators of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine and noradrenaline is inhibited. Opioids also inhibit the release of vasopressin, somatostatin, insulin and glucagon. Alfentanil's analgesic activity is, most likely, due to its conversion to morphine. Opioids close N-type voltage-operated calcium channels (OP2-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (OP3 and OP1 receptor agonist). This results in hyperpolarization and reduced neuronal excitability. Opioids are the most effective and widely used drugs in the treatment of severe acute and chronic pain. They act through opioid receptors that belong to the family of G protein-coupled receptors. Three classes of opioid receptors (mu, delta, kappa), expressed in the central and peripheral nervous system, have been identified. The analgesic effect of opioids is mediated through multiple pathways of opioid receptor signaling (e.g., G(i/o) coupling, cAMP inhibition, Ca(++) channel inhibition). The standard exogenous opioid analgesics used in the operating room are fentanyl, sufentanil, morphine, alfentanil, and remifentanil.
Pharmacodynamics
Alfentanil is a synthetic opioid analgesic. Alfentanil interacts predominately with the opioid mu-receptor. These mu-binding sites are discretely distributed in the human brain, spinal cord, and other tissues. In clinical settings, alfentanil exerts its principal pharmacologic effects on the central nervous system. Its primary actions of therapeutic value are analgesia and sedation. Alfentanil may increase the patient's tolerance for pain and decrease the perception of suffering, although the presence of the pain itself may still be recognized. In addition to analgesia, alterations in mood, euphoria and dysphoria, and drowsiness commonly occur. Alfentanil depresses the respiratory centers, depresses the cough reflex, and constricts the pupils.
Biological pathways
Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.
This drug in other countries
The same active ingredient registered across other registries we cover - including different brands.