Fentanyl is a topical narcotic analgesic (pain reliever) available as a patch (transdermal delivery system) which allows continuous dosing of a potent narcotic opioid analgesic released per hour. Fentanyl is by no means an initial agent for pain relief and is indicated for persistent, moderate to severe chronic pain in patients requiring continuous relief of pain not previously managed by other medications such as non-steroidal anti-inflammatories, acetaminophen/opioid combination medications or immediate release dosing opioids, and in opioid tolerant patients only. It should be avoided in acute pain or in post-operative patients due to its respiratory depressive effects which could be exacerbated by general anesthetic agents, and in patients with previous demonstrated sensitivity reactions to the short acting opioids or with allergies to adhesives.

The hourly dose is dependent upon the size of the patch; 25mcg(micrograms)/hour contains 2.5mg and is 10cm2 in size which is the minimal hourly dosing available. Other sizes and strengths are 50 mcg/hour containing 5mg and is 20 cm2, 75mcg//hours containing 7.5mg which is 30 cm2, and 100mcg/hour containing 10mg which is 40cm2. The last three patches are for opioid tolerant (those patients having had previous doses of an opioid and are known to tolerate the narcotic well).

As an opioid analgesic it exerts its pharmacological action by interacting with an opioid receptor located in the brain, spinal cord and peripheral tissues with primary affect on the central nervous system (the brain and spinal cord) producing relief of pain and sedation. Patients on Fentanyl may still recognize the symptoms of pain but have an increased tolerance and reduced perception. By also producing euphoria, altered mood, and dysphoria and drowsiness, the patient may be able to cope better with the painful situation.

Drug interactions with Fentanyl can occur with various medications a patient may be simultaneous prescribed. -Benzodiazepines (i.e. Valium, Xanax, etc) Due to the CNS (central nervous system) depressants effects, the dose of this drug class should be reduced by 50% to avoid excessively lowered blood pressure (hypotension)

-Certain drugs with similar modes of metabolism (CYP3A4 inducers) some drugs induced certain metabolic enzymes which increased the clearance or elimination of Fentanyl and reduced analgesic effect- such as phenytoin and carbamazepine (anti-epileptic medications) and rifampin (pulmonary medication for infection). Some medications inhibit the enzyme CYP3A4, and caused increased levels of Fentanyl such as erythromycin (antibiotic), antifungals (ketoconazole, etc). In either case, these dosages must be adjusted accordingly.

-Patients with a history of drug or alcohol dependence should be monitored carefully and concomitant use with alcohol should be avoided.

Fentanyl should not be used in labor and delivery and not recommended for nursing mothers or in children younger than two yeas of age. Patients over the age of sixty may have reduced clearance of Fentanyl and should also be monitored closely if the drug is indicated.

Various precautions also should be followed with Fentanyl. The proper disposal of the used patches is important as some medication may remain the in the reservoir or the patch. The patch should be folded over on itself (i.e. adhesive to adhesive) and flushed down the toilet immediately after removal.

Adverse reactions may occur affecting various organ systems of the body, which are age related due to metabolic maturity.

Adults may experience general abdominal pain and headache, while the pediatric patient also may experience fever, syncope (feeling of feinting), allergic like reactions and flushing. Arrhythmia and chest pain in the adult and hypertension and tachycardia (fast heart beat in the pediatric patients. The adult nervous system may manifest as confusion, hallucinations, nervousness, euphoria, tremors, speech disorders, abnormal thoughts, gait, and dreams, numbness, paranoia, poor coordination, while the pediatric patient may also experience convulsions, agitation. Coughing up blood (hemoptysis, hiccups, pharyngitis in the adults patient, and rhinitis (running nose) coughing in the pediatric patient may occur. Both may experience difficulty urinating, with rashes, pruritis (itching) and excessive sweating.

Application of the patch should be performed immediately after opening the package and applied to non-irritated or non-irradiated skin (i.e. skin not previous exposed to radiation for cancer treatments), on a flat skin surface on the chest, back, or upper arm avoiding hair. If necessary if hair is present it SHOULD NOT BE SHAVED BUT CLIPPED, prior to application and skin should only be cleansed with CLEAR WATER. The patch should be pressed firmly and held for 30 seconds any may remain up to 72 hours.

REFERENCES

THE RX CONSULTANT, “Chronic Nonmalignant Pain and Use of Opioids” Vol. XI, #5, May 2002

PDR, PHYSICIANS DESK REFERENCE, 59th Edition 2005

MPR, Monthly Prescribing Reference, 2011 edition, Pain Management.

As a podiatrist, I have not had the necessity to prescribe Fentanyl, however from past staff hospital experience as a Pharmacist, I have often seen the benefits of this mediation provide much needed pain relief for the chronic pain patient, and note the ease of compliance due to the application of the patch.

ADDITIONAL REFERENCES

American Pain Society

Centers For Disease Control

MedlinePlus

See our other pain medication discussions.