Fentanyl

Fentanyl is a potent opioid analgesic and is mainly a -opioid agonist. It is used as an adjunct to general anesthetics.

Drug Names

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Fentanyl patch 12 mcg/hr	FENT08	DD
Fentanyl patch 25 mcg/hr	FENT07	DD

Mechanism of Action

Equivalent doses of opioid analgesics

Analgesic/Route	Dose
Codeine: PO	100 mg
Diamorphine: IM, IV, SC	3 mg
Dihydrocodeine: PO	100 mg
Morphine: PO	10 mg
Morphine: IM, IV, SC	5 mg
Oxycodone: PO	6.6 mg
Tramadol: PO	100 mg

Route of Administration

Fentanyl is usually given parenterally, intranasally, or by the transmucosal route as the citrate, or in transdermal patches as the base.

Dosage

For the treatment of intractable chronic pain in adults:

Chronic severe pain:

Transdermal patches: 12mcg/72hours, adjusted at 48-72hours in steps of 12-25mcg/hour if needed.

Max: 300mcg/hours

• Doses should be individually titrated according to previous opioid usage
• Use of a patch providing 25 micrograms of fentanyl per hour is equivalent to about 60 to 90mg daily of oral morphine sulphate
• More than one patch may be applied if doses greater than 100 micrograms/hour are required
• Elderly or debilitated patients should be observed carefully for signs of toxicity

Transmucosal: a lozenge-on-a-stick dosage form, for management of breakthrough cancer pain.

• An initial unit dose of 200 micrograms may be taken over 15 minutes for breakthrough pain and repeated if necessary, after a further 15 minutes.

Buccal and sublingual tablets containing fentanyl citrate for transmucosal delivery.

• An initial dose of 100 micrograms may be taken for breakthrough pain and repeated once if necessary after 30 minutes.

Intranasal preparations containing fentanyl citrate, equivalent to 50 to 400 micrograms of fentanyl per spray.

• An initial dose or 50 to 100 micrograms is sprayed into one nostril for breakthrough pain and repeated once if necessary, after 10 minutes. Patients must wait at least 2 or 4 hours before treating another episode.

Doses in children:

Fentanyl is usually given by intravenous injection as an adjunct to general anaesthesia. 2 – 12 years: 1 to 3 micrograms/kg

Transdermal patches ranging from 12 to 100 micrograms/hour may be used for the treatment of intractable chronic pain in children aged 2 to 16 years. The initial dose should be based on the previous 24-hour opioid requirement.

Use of a patch providing 12 micrograms of fentanyl per hour is equivalent to about 30 to 44 mg daily of oral morphine sulphate.

Patches should be applied to the upper backs of young children to minimize the potential for removal.

Side Effects

As for Opioid Analgesic in general

The commonest adverse effects are nausea, vomiting, constipation, drowsiness and confusion.

Large doses of opioids produce respiratory depression and hypotension, with circulatory failure and deepening coma. Death may occur from respiratory failure.

Treatment of Adverse Effects

1. Constipation can be treated with laxatives such as senna tables and lactulose.
2. Nausea and vomiting can be alleviated by metoclopramide.
3. Intensive supportive therapy may be required to correct respiratory failure and shock. Naloxone is used for rapid reversal of the severe respiratory depression and coma.

Euphoria, nausea and vomiting, respiratory depression, constipation and cough suppression, hypertension, application-sited reaction, appetite changes, anxiety

Pharmacokinetics

Oral bioavailability	After transmucosal delivery, up to 50% of the dose is rapidly absorbed from the buccal mucosa; the remainder is swallowed and slowly absorbed from the gastrointestinal tract. Some first-pass metabolism occurs via this route. The absolute bioavailability of transmucosal delivery is about half that for intravenous fentanyl. The absolute bioavailability of intranasal delivery is bout 89% and fentanyl is absorbed very rapidly through the nasal mucosa. Absorption is slow after transdermal application.
Onset of action	After parenteral doses fentanyl citrate has a rapid onset and short duration of action.
Elimination half-life	It may take 17 hours or longer for plasma concentrations of fentanyl to decrease by 50% after removal of a transdermal patch; patients who have had adverse effects should be monitored for up to 24 hours.
Metabolism	fentanyl is mainly metabolized in the liver into the inactive metabolite

Drug Management

Efficiency

Pain control

Safety

mental status, blood pressure, respiratory drive, and misuse / overuse.

Caution

Transdermal patch is not suitable for acute pain Tolerance and dependence

Contraindication

Transdermal patch is not suitable for acute pain

FAQ

How should I use the patch?

Follow the doctor's prescription, Apply the patch to non-hairy skin. Remove from the sealed pouch, peel off the protective liner, and apply right away to the skin. Press firmly, making sure the contact is complete.

What should I avoid while using?

Do not use the patch if it appears to be broken, cut, or damaged. Avoid abrupt withdrawal

What happen if I overdose?

Emergency situation, called 999 immediately Antidote: Naloxone

What happen if I miss a dose?

Take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.