1. Name Of The Medicinal Product
Rapifen®
2. Qualitative And Quantitative Composition
Each ml of Rapifen contains alfentanil hydrochloride 544 micrograms, equivalent to 500 micrograms alfentanil base.
3. Pharmaceutical Form
Aqueous injection.
4. Clinical Particulars
4.1 Therapeutic Indications
As an analgesic supplement for use before and during anaesthesia.
It is indicated for:
1. Short procedures and outpatient surgery.
2. Procedures of medium and long duration when given as a bolus followed by supplemental doses or by continuous infusion.
At very high doses, Rapifen may be used as an anaesthetic induction agent in ventilated patients.
4.2 Posology And Method Of Administration
For intravenous administration.
Rapifen by the intravenous route can be administered to both adults and children. The dosage of Rapifen should be individualised according to age, bodyweight, physical status, underlying pathological condition, use of other drugs and type of surgery and anaesthesia. The usual recommended dosage regimen is as follows:
Adults
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Initial
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Supplemental
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Spontaneous respiration
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500 µg (1 ml)
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250 µg (0.5 ml)
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Assisted ventilation
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30-50 µg/kg
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15 µg/kg
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|
|
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Children
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Initial
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Supplemental
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Assisted ventilation
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30-50 µg/kg
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15 µg/kg
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If desired, Rapifen can be mixed with sodium chloride injection BP, dextrose injection BP or compound sodium lactate injection BP (Hartmann's solution). Such dilutions are compatible with plastic bags and giving sets. These dilutions should be used within 24 hours of preparation.
Children may require higher or more frequent dosing owing to a shorter half-life of Rapifen in this age group. The elderly and debilitated may require lower or less frequent dosing owing to a longer half-life of Rapifen in this age group (dilution may be helpful).
In spontaneously breathing patients, the initial bolus dose should be given slowly over about 30 seconds (dilution may be helpful).
After intravenous administration in unpremedicated adult patients, 1 ml Rapifen may be expected to have a peak effect in 90 seconds and to provide analgesia for 5-10 minutes. Periods of more painful stimuli may be overcome by the use of small increments of Rapifen. For procedures of longer duration, additional increments will be required.
In ventilated patients, the last dose of alfentanil should not be given later than about 10 minutes before the end of surgery to avoid the continuation of respiratory depression after surgery is complete.
In ventilated patients undergoing longer procedures, Rapifen may be infused at a rate of 0.5-1 microgram/kg/minute. Adequate plasma concentrations of alfentanil will only be achieved rapidly if this infusion is preceded by a loading dose of 50-100 microgram/kg given as a bolus or fast infusion over 10 minutes.
Lower doses may be adequate, for example, in geriatric patients or where anaesthesia is being supplemented by other agents.
The infusion should be discontinued up to 30 minutes before the anticipated end of surgery.
Increasing the infusion rate may prolong recovery. Supplementation of the anaesthetic, if required, for periods of painful stimuli, is best managed by extra bolus doses of Rapifen (1-2 ml) or low concentrations of a volatile agent for brief periods.
Patients with severe burns presenting for dressing, etc, have received a loading dose of 18-28 µg/kg/min for up to 30 minutes without requiring mechanical ventilation. In heart surgery, when used as a sole anaesthetic, doses in the range of 12-50 mg/hour have been used.
4.3 Contraindications
Obstructive airways disease or respiratory depression if not ventilating.
Concurrent administration with monoamine oxidase inhibitors or within 2 weeks of their discontinuation.
Administration in labour or before clamping of the cord during caesarean section due to the possibility of respiratory depression in the newborn infant.
Patients with a known intolerance to alfentanil and other morphinomimetics.
4.4 Special Warnings And Precautions For Use
Warnings:
Following administration of Rapifen, a fall in blood pressure may occur. The magnitude of this effect may be exaggerated in the hypovolaemic patient or in the presence of concomitant sedative medication. Appropriate measures to maintain a stable arterial pressure should be taken.
Significant respiratory depression and loss of consciousness will occur following administration of Rapifen in doses in excess of 1 mg and is dose-related. This and the other pharmacological effects of Rapifen are usually of short duration and can be reversed by the specific opioid antagonists (e.g. naloxone). Additional doses of the antagonists may be necessary because the respiratory depression may last longer than the duration of action of the opioid antagonist.
Like other opioids, alfentanil may cause bradycardia, an effect that may be marked and rapid in onset but which can be antagonised by atropine. Particular care must be taken following treatment with drugs which may depress the heart or increase vagal tone, such as anaesthetic agents or beta-blockers, since they may predispose to bradycardia or hypotension. Heart rate and blood pressure should therefore be monitored carefully. If hypotension or bradycardia occur, appropriate measures should be instituted.
Cardiac arrest following bradycardia has been reported on very rare occasions in non-atropinised patients. Therefore it is advisable to be prepared to administer an anticholinergic drug.
Precautions:
It is wise to reduce the dosage in the elderly and debilitated patients. In hypothyroidism, pulmonary disease, decreased respiratory reserve, alcoholism and liver or renal impairment the dosage should be titrated with care and prolonged monitoring may be required.
Patients on chronic opioid therapy or with a history of opioid abuse may require higher doses.
Rapifen may induce muscle rigidity during induction. Rigidity, which may also involve the thoracic muscles, can be avoided by the following measures:
• Slow IV injection (usually sufficient for lower doses);
• Premedication with a benzodiazepine;
• Administration of a muscle relaxant just prior to administration of Rapifen.
• Non-epileptic (myo)clonic movements can occur.
As with all potent opioids, profound analgesia is accompanied by marked respiratory depression, which may persist into or recur in the early postoperative period. Care should be taken after infusions or large doses of alfentanil to ensure that adequate spontaneous breathing has been established and maintained in the absence of stimulation before discharging the patient from the recovery area. Resuscitation equipment and narcotic antagonists should be readily available. Hyperventilation during anaesthesia may alter the patient's response to CO2, thus affecting respiration postoperatively.
The use of rapid bolus injections of opioids should be avoided in patients with compromised intracerebral compliance; in such patients a transient decrease in the mean arterial pressure has occasionally been accompanied by a transient reduction of the cerebral perfusion pressure.
This medicinal product contains less than 1 mmol sodium (23 mg) per 5 mg dose, i.e. essentially 'sodium-free'.
4.5 Interaction With Other Medicinal Products And Other Forms Of Interaction
Potential for Rapifen to affect other medicinal products
In combination with alfentanil, the blood concentrations of propofol are 17% higher than in the absence of alfentanil. The concomitant use of alfentanil and propofol may require a lower dose of Rapifen.
Potential for other medicinal products to affect Rapifen
Alfentanil is metabolised mainly via the human cytochrome P450 3A4 enzyme. In vitro data suggest that potent cytochrome P450 3A4 enzyme inhibitors (e.g., ketoconazole, itraconazole, ritonavir) may inhibit the metabolism of alfentanil. Available human pharmacokinetic data indicate that the metabolism of alfentanil is inhibited by fluconazole, erythromycin, diltiazem and cimetidine (known cytochrome P450 3A4 enzyme inhibitors). This could increase the risk of prolonged or delayed respiratory depression. The concomitant use of such drugs requires special patient care and observation; in particular, it may be necessary to lower the dose of Rapifen.
Treatment with drugs which may depress the heart or increase vagal tone, such as beta-blockers and anaesthetic agents, may predispose to bradycardia or hypotension. Bradycardia and possibly cardiac arrest can occur when Rapifen is combined with non-vagolytic muscle relaxants.
The use of opioid premedication, barbiturates, benzodiazepines, neuroleptics, halogenic gases and other non-selective CNS depressants may enhance or prolong the respiratory depressant effects of alfentanil.
If other narcotic or CNS depressant drugs are used concurrently with alfentanil, the effects of the drugs can be expected to be additive. When patients have received such drugs the dose of alfentanil required will be less than usual. Likewise, following the administration of alfentanil, the dose of other CNS depressant drugs should be reduced.
4.6 Pregnancy And Lactation
Although no teratogenic or acute embryotoxic effects have been observed in animal experiments, insufficient data are available to evaluate any harmful effects in man.
Consequently, it is necessary to consider possible risks and potential advantages before administering this drug to pregnant patients.
IV administration during childbirth (including Caesarian section) is not recommended, because alfentanil crosses the placenta and because the foetal respiratory centre is particularly sensitive to opiates. If, however, Rapifen is administered, an antidote should always be at hand for the child.
Alfentanil may appear in breast milk. It is therefore recommended that breast feeding is not initiated within 24 hours of treatment.
4.7 Effects On Ability To Drive And Use Machines
Where early discharge is envisaged, patients should be advised not to drive or operate machinery for the 24 hours following administration.
4.8 Undesirable Effects
Adverse Drug Reactions
The most frequently reported ADRs (incidence
Very common (
Table 1
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Adverse Drug Reactions reported in clinical trials and/or postmarketing
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|
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|
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Frequency Category
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|
|
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System Organ Class
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Very Common
(
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Common
(
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Uncommon
(
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Rare
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Not Known
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Immune System Disorders
|
|
|
|
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Hypersensitivity (including anaphylactic reaction, anaphylactoid reaction and urticaria
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Psychiatric Disorders
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Euphoric Mood
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Agitation; Crying
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Disorientation
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Nervous System Disorders
|
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Movement Disorder; Dizziness; Sedation; Dyskinesia
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Headache; Somnolence; Unresponsive to Stimuli
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Loss of Consciousness
(postoperative period); Convulsion; Myoclonus
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Eye Disorders
|
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Visual Disturbance
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|
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Miosis
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Cardiac Disorders
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Bradycardia; Tachycardia
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Arrhythmia; Heart Rate Decreased
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Cardiac Arrest
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Vascular Disorders
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Hypotension; Hypertension;
Blood Pressure Decreased; Blood Pressure Increased
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Vein Pain
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Respiratory, Thoracic and Mediastinal Disorders
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Apnoea
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Hiccups; Hypercapnia; Laryngospasm; Respiratory Depression (including fatal outcome)
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Bronchospasm; Epistaxis
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Respiratory Arrest; Cough
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Gastrointestinal Disorders
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Nausea; Vomiting
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Skin and Subcutaneous Tissue Disorders
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|
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Dermatitis Allergic; Hyperhidrosis
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Pruritus
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Erythema; Rash
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Musculoskeletal and Connective Tissue Disorders
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Muscle Rigidity
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General Disorders and Administration Site Conditions
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Chills; Injection Site Pain;
Fatigue
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Pain
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Pyrexia
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Injury, Poisoning and Procedural Complications
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Procedural Pain
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Agitation Postoperative;
Airway Complication of Anaesthesia; Confusion
Postoperative
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Anaesthetic Complication
Neurological; Procedural
Complication; Endotracheal
Intubation Complication
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4.9 Overdose
The manifestations of alfentanil overdose are generally an extension of its pharmacological action, which include the following:
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Action
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Bradycardia
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Anticholinergics such as atropine or glycopyrrolate.
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Hypoventilation or apnoea
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O2 administration, assisted or controlled respiration and an opioid antagonist may be required.
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Muscle rigidity
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Intravenous neuromuscular blocking agent may be given.
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If hypotension is severe or persists, the possibility of hypovolaemia should be considered and controlled with appropriate parenteral fluid administration.
The suggested treatments given above do not preclude the use of other clinically indicated counter measures.
Body temperature and adequate fluid intake should be maintained and the patient observed for 24 hours. A specific opioid antagonist (e.g. naloxone) should be available to treat respiratory depression.
5. Pharmacological Properties
5.1 Pharmacodynamic Properties
The analgesic potency of Rapifen is one quarter that of fentanyl. The duration of action of Rapifen is one third that on an equianalgesic dose of fentanyl and is clearly dose-related. Its depressant effects on respiratory rate and alveolar ventilation are also of shorter duration than those of fentanyl.
The onset of action of Rapifen is four times more rapid than that of an equianalgesic dose of fentanyl. The peak analgesic and respiratory depressant effects occur within 90 seconds.
In man, alfentanil at therapeutic doses had no detrimental effects of myocardial performance. The cardiovascular stability is remarkable both in healthy and poor-risk patients. The only changes seen in blood pressure and heart rate are transient, slight decreases occurring immediately after induction. The incidence and degree of respiratory depression is less and of shorter duration after alfentanil than with fentanyl. Like other narcotic analgesics, alfentanil increases the amplitude of the EEG and reduces its frequency. Alfentanil reduces intraocular pressure by about 45%. It blocks increases in plasma cortisol and in plasma antidiuretic and growth hormones throughout surgery and prevents increases in plasma catecholamines up to but not during or after cardiopulmonary bypass in patients undergoing open heart surgery.
5.2 Pharmacokinetic Properties
Alfentanil is a synthetic opioid with µ-agonist pharmacological effects.
After bolus injections ranging from 2.4 to 125 µg/kg, plasma levels in man decay triexponentially with a terminal half life of approximately 90 minutes. Total distribution volume varies from 0.4 to 1.0 L/kg, indicating a limited distribution of alfentanil to the tissues. Plasma clearance, varying from 3.3 to 8.3 ml/kg/min represents approximately one third of liver plasma flow indicating that elimination of alfentanil is not flow dependent. Since only 0.4% of the dose is excreted with the urine as unchanged drug, elimination of alfentanil occurs mainly by metabolism.
These main parameters in patients undergoing surgery are similar to those in healthy volunteers. Only when the drug was given as the sole anaesthetic in a continuous high infusion over about 5 hours was the clearance of alfentanil reduced resulting in a plasma half-life of about 200 minutes, the distribution volume not being markedly changed.
Plasma protein binding of alfentanil is 92%, mainly due to a strong binding to the 'acute phase' α1 acid-glycoprotein. It is not bound to the blood cells. Pharmacokinetics were comparable in rats, dogs and man. The elderly show a longer half-life for Rapifen after IV bolus doses.
Special Populations
Paediatric patients
Protein binding in newborns is 75% and increases in children to 85%. The plasma clearance in newborns is approximately 7.2 ± 3.2mL/kg/min and 4.7 ± 1.7 mL/kg/min in children between 4.5 to 7.75 years. The volume of distribution at steady state was 1230 ± 520 mL/kg in newborns and 163.5 ± 110 mL/kg in children. The half-life is 146 ± 57 minutes in newborns and 40.2 ± 8.9 minutes in children.
Hepatic Impairment
After administration of a single intravenous dose of 50 µg/kg, the terminal half-life in cirrhotic patients is significantly longer than in controls. The volume of distribution remains unchanged. The free fraction of alfentanil increases in cirrhotic patients to 18.5% compared with 11.5% in controls. This increase in free fraction together with a reduction in clearance from 3.06 mL/min/kg in controls to 1.60 mL/min/kg in cirrhotic patients will result in a more prolonged and pronounced effect (see Section 4.4.).
Renal Impairment
The volume of distribution and clearance of the free fraction is similar in renal failure patients and healthy controls. The free fraction of alfentanil in patients with renal failure is increased to 12.4 to 19 % compared with 10.3 to 11% in controls. This may result in an increase in clinical effects of alfentanil (see Section 4.4.).
5.3 Preclinical Safety Data
Preclinical effects observed were only at exposures considered sufficiently in excess of the maximum human exposure indicating little relevance to clinical use.
6. Pharmaceutical Particulars
6.1 List Of Excipients
Sodium chloride
Water for injection
6.2 Incompatibilities
See 'Dosage and dosage schedules'.
6.3 Shelf Life
5 years.
6.4 Special Precautions For Storage
Store in a controlled drug store, at or below 25°C.
6.5 Nature And Contents Of Container
Colourless glass one-point-cut ampoules (PhEur, Type I).
Pack size: packs of 10 x 2 ml ampoules; packs of 5 and 10 x 10 ml ampoules.
6.6 Special Precautions For Disposal And Other Handling
For single use only. Discard any unused contents.
7. Marketing Authorisation Holder
Janssen-Cilag Limited
50-100 Holmers Farm Way
High Wycombe
Buckinghamshire
HP12 4EG
UK
8. Marketing Authorisation Number(S)
PL 0242/0091
9. Date Of First Authorisation/Renewal Of The Authorisation
27 July 1983/30 March 2004
10. Date Of Revision Of The Text
26th May 2010