Onset
of action:
Serum concentrations increase gradually following initial
application, levelling off between 12 and 24 hours.
Distribution:
Highly lipophilic, redistributes into muscle and fat.
Metabolism:
Hepatic via cytochrome P450 3A4 isoenzyme system.
Excretion:
Urine (primarily as metabolites, 10% as unchanged drug). |
Cardiovascular:
Hypotension, bradycardia.
Central nervous system:
Somnolence, confusion, asthenia.
Gastrointestinal:
Nausea, vomiting, constipation, dry mouth.
Respiratory:
Hypoventilation.
Skin:
Sweating, pruritus , rash, applications site reaction--erythema,
papules, itching, edema.
Urogenital:
Urinary retention. |
CNS
depressants:
Increased sedation with CNS depressants, phenothiazines
CYP3A4 inhibitors:
May increase the levels/effects of fentanyl. Example
inhibitors include azole antifungals, ciprofloxacin,
clarithromycin, diclofenac, doxycycline, erythromycin,
imatinib, isoniazid, nefazodone, nicardipine, propofol,
quinidine, and verapamil.
MAO inhibitors:
Severe and unpredictable potentiation by MAO inhibitors
has been reported with opioid analgesics.
St John's wort may decrease fentanyl levels. Avoid valerian,
kava kava, gotu kola (may increase CNS depression). |
DO
NOT
cut or damage the patch as this will result in uncontrolled
drug delivery to patient.
DO NOT expose the application site
to direct external heat sources such as heating pads
& saunas. This is because increase in temperature
may result in increase fentanyl release from transdermal
system. |
