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piroxicam (Feldene)
Tradename: Feldene.
Indications:
1) temporary relief of minor aches, pains, fever & inflammation
2) symptomatic treatment of acute & chronic rheumatoid arthritis
3) osteoarthritis
4) ankylosing spondylitis
Dosage:
1) 20 mg PO QD
2) do not assess effect of therapy for 2 weeks
3) use with caution or reduced doses in the elderly
Tabs: 10, 20 mg.
Pharmacokinetics:
1) food delays absorption [5]
2) metabolized in the liver by cyt P450 2C9
3) onset of action is several hours
4) duration of action is 24 hours
5) elimination 1/2life is 48 hours
6) 5% of drug is excreted unchanged in the urine
Monitor: liver function tests periodically [6]
Adverse effects:
1) common (> 10%)
- rash, dizziness, abdominal cramps, heartburn, indigestion, nausea
2) less common (1-10%)
- itching, tinnitus, fluid retention, headache, nervousness, vomiting
3) uncommon (< 1%)
- congestive heart failure, hypertension, arrhythmias, epistaxis, confusion, hallucinations, aseptic meningitis, depression, peripheral neuropathy, urticaria, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, gastritis, GI ulceration, cystitis, agranulocytosis, anemia, hemolytic anemia, bone marrow depression, leukopenia, thrombocytopenia, hepatitis, angioedema, allergic rhinitis, toxic amblyopia, blurred vision, conjunctivitis, dry eyes, decreased hearing, polyuria, shortness of breath, polydypsia, tachycardia, hot flashes, drowsiness, insomnia, acute renal failure
4) other
a) GI effects & bleeding may be more prominent with piroxicam than with other NSAIDs
b) high incidence of phototoxic skin eruptions
c) worsening of renal insufficiency ;;;********|**********|**********|**********|**********|*********|**********|*********
Drug interactions:
1) corticosteroids
a) increase clearance of salicylates
b) increased nephrotoxicity
c) increased GI toxicity
2) decreased anti-hypertensive effects of ACE inhibitors
3) coumadin: prolonged bleeding time
4) piroxicam decreases clearance & increases toxicity of:
a) methotrexate
b) Li+
c) digoxin
5) any drug which inhibits cyt P450 2C9 can increase piroxicam levels
6) any drug which induces cyt P450 2C9 can diminish piroxicam levels
Laboratory:
1) specimen:
a) serum, plasma, urine
b) stable for 14 days at -20 degrees C
2) methods: HPLC
Mechanism of action:
1) oxicam class NSAID
2) analgesic, antipyretic, anti-inflammatory
3) non-selective cyclooxygenase inhibitor
Interactions
drug interactions
drug adverse effects of NSAIDs
monitor with non steroidal anti-inflammatory agents (NSIADs)
Related
cytochrome P450 2C9; cytochrome P450 BP-1; cytochrome P450 MP-4; S-mephenytoin-4-hydroxylase; limonene 6-monooxygenase; limonene 7-monooxygenase (CYP2C9, CYP2C10)
General
non-steroidal anti-inflammatory agent (NSAID)
peroxisome proliferator; PPAR agonist; PPAR gamma agonist
Properties
INHIBITS: cyclooxygenase
MISC-INFO: elimination route LIVER
1/2life 14-158 HOURS
therapeutic-range >6.7 UG/ML
protein-binding >99%
elimination by hemodialysis -
peritoneal dialysis -
pregnancy-category C
D <3rd trimester>
safety in lactation -
Database Correlations
PUBCHEM correlations
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed.,
W.B. Saunders, 1995
- Harrison's Principles of Internal Medicine, 14th ed.
Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 470
- Prescriber's Letter 17(7): 2010
Recommended Lab Monitoring for Common Medications
Liver Function Test Scheduling
Detail-Document#: 260704
(subscription needed) http://www.prescribersletter.com