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Non-Steroidal Anti-Inflammatory Drugs

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Non-Steroidal Anti-Inflammatory Drugs ibuprofen Meghin Gjerswold 12.01.2006 UWSOP at Genelex NSAID use NSAIDs are available OTC NSAIDs can be toxic on their own ... – PowerPoint PPT presentation

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Title: Non-Steroidal Anti-Inflammatory Drugs


1
Non-Steroidal Anti-Inflammatory Drugs
ibuprofen
  • Meghin Gjerswold
  • 12.01.2006
  • UWSOP at Genelex

2
NSAID use
  • NSAIDs are available OTC
  • NSAIDs can be toxic on their own
  • People who take NSAIDs (elderly people) often
    take many drugs which can lead to dangerous
    interactions
  • NSAIDs are metabolized by multiple hepatic
    pathways

3
Adverse effects
  • Nephrotoxic
  • Bleeding problems
  • Increase blood pressure
  • FDA requires medication guide be dispensed with
    every NSAID prescription www.fda.gov/cder/drug/i
    nfopage/COX2/NSAIDmedguide.pdf
  • FDA fact
  • gt70,000 hospitalizations per year and
    10,000-20,000 deaths per year can be associated
    with NSAID use

4
Potential interaction types
  • Pharmacokinetic interactions involve
    absorption, distribution, elimination
  • Pharmacodynamic interactions involve drug
    effects and/or toxicity

5
Pharmacokinetic interactions
  • Absorption
  • Protein binding
  • P450 interactions
  • 2D6
  • 2C9
  • 2C19
  • 3A4
  • Renal elimination

6
Decreased absorption of NSAIDs
  • Sucralfate coat the stomach to protect from
    bleed/ulcers
  • H2-blockers/antacids decrease stomach pH to
    protect from bleed/ulcers
  • Bile acid sequesterants bind to bile acid to
    prevent manufacture of cholesterol
  • Evidence points to lack of clinically significant
    effect with coadministration of these drugs

7
Protein binding
  • Most NSAIDs are greater than 95 protein bound
  • Potential for drug-drug interactions via
    competition for protein binding sites
  • Warfarin
  • Aspirin
  • Digoxin

8
Warfarin protein binding
  • Strongly protein bound and only unbound fraction
    is active
  • Ketorolac reduces protein binding of warfarin but
    apparently has no effect on prothrombin time (PT)
  • Meloxicam has been shown to increase plasma AUC
    of s-warfarin, but again no
  • change in PT
  • Most trials and PIs state
  • that NSAIDs have no effect
  • on pharmacokinetics of
  • warfarin, but that patients
  • should still be monitored for
  • bleeding complications

Warfarin in its natural habitat
9
Aspirin protein binding
  • Common OTC drug that is highly protein bound
  • Used as NSAID and as cardio-protectant and as
    preventative for stroke
  • Aspirin demonstrated to significantly decrease
    plasma NSAID levels secondary to displacement
    from protein binding sites
  • Evidence that some NSAIDs may inhibit the
    anti-platelet activity of aspirin

10
Digoxin protein binding
  • Digoxin is highly protein bound and is easily
    displaced by other drugs
  • Most studies show that NSAIDs and digoxin are
    safe to take together
  • However, it is well documented that indomethacin
    can increase the plasma levels of digoxin to a
    toxic level
  • Bottom line patients on digoxin should avoid
    indomethacin

Digoxin in its natural habitat
11
P450 interactions
  • Most P450 interactions involve changing the
    metabolism of the NSAIDs rather than the
    interacting drug
  • NSAIDs have wide therapeutic range so that
    fluctuations in metabolism rates has less adverse
    effect than could otherwise be expected
  • Not as exciting as we might have hoped

12
CYP2C9
  • NSAID substrates
  • celecoxib, diclofenac, etodolac, ibuprofen,
    indomethacin, meloxicam, naproxen, piroxicam
  • NSAID inhibitors
  • diclofenac, etodolac, ketoprofen,
  • incredibly weak

13
Fluconazole/voriconazole
  • Antifungal agents that inhibit 2C9
  • Increase celecoxib plasma concentration times 2
  • Significant increases in ibuprofen plasma
    concentrations
  • Significance potential for excessive NSAID
    levels that could lead to nephrotoxicity and
    increased cardiovascular events

14
Rifampicin
  • Anti-tubercular agent that induces 2C9
  • Shown to significantly decrease plasma levels of
    celecoxib
  • Not as immediately scary because levels will be
    decreased rather than increased
  • Patients may not have adequate pain control,
    however

15
Warfarin
  • Anticoagulant metabolized by 2C9
  • Competition for metabolism may lead to excessive
    anticoagulation celecoxib clinical trial has
    shown risk of excessive bleed in individuals with
    2C92, 3 variants
  • Though several NSAIDs have been implicated in
    inhibiting 2C9, studies dont show
    pharmacokinetic effect on warfarin

16
CYP2D6
  • Inhibited by celecoxib
  • Substrates
  • Beta blockers
  • Antidepressants/antipsychotics
  • Antihistamines
  • Opiates
  • Clinical significance?

17
CYP2C19
  • Inhibited by indomethacin
  • Metabolizes carisoprodol, citalopram, clozapine,
    diazepam, doxepin, fluoxetine, phenytoin,
    propranolol
  • Clinical trials are lacking for these
    interactions!!

18
CYP3A4
  • Metabolizes meloxicam, diclofenac
  • Amiodarone, chloramphenicol, clarithromycin,
    cyclosporine, ethinyl estradiol, azole
    antifungals, grapefruit inhibit
  • Barbiturates, carbamazepine, phenytoin, rifampin,
    St Johns Wort induce
  • Lacking studies!!

19
Renal elimination
  • Probenecid is a competitive inhibitor of
    organic acid transport in the kidney
  • Get increased levels of NSAIDs by several fold
  • May lead to decreased effect of probenecid
  • Methotrexate and Lithium may have decreased renal
    clearance in the presence of NSAIDs though this
    may be attributable to the pharmacodynamic
    effects of the NSAIDs

20
Pharmacodynamic
  • Effects on other drugs due to inhibition of renal
    prostaglandins
  • Increased adverse effects
  • Bleeding
  • GI toxicity
  • Nephrotoxicity

21
Inhibition of renal prostaglandins
  • Loss of BP control with beta blockers, ACE
    inhibitors, diuretics
  • Toxic levels of methotrexate due to decreased
    excretion
  • Toxic levels of lithium due to decreased
    excretion

22
Increased risk of nephrotoxicity
  • Cyclosporine
  • Methotrexate
  • Triamterene
  • Tacrolimus
  • Aminoglycosides

23
Increased GI bleed
  • SSRIs
  • Salicylates
  • Anticoagulants
  • H2 blockers
  • Bisphosphonates?

24
NSAID summary
  • Interactions possible and dangerous, but some are
    rather dubious, allowing many of them to be safe
    enough for OTC use
  • Most interaction effects are on NSAIDs. This
    allows for increased safety in the presence of
    P450 interactions due to the wide therapeutic
    range of many NSAIDs
  • It would be interesting to see more clinical
    trials on the P450 interactions with NSAIDs, but
    the drugs are old and numerous and proven
    relatively safe, so drug companies will take
    their monies eslewhere

25
Keeping GeneMedRx Current
  • Documentation for 97 new NSAID-drug interactions
    were found and added as new notes
  • Documentation for 14 new NSAID class-drug class
    interactions were found and added as new notes
  • P450 effects of NSAIDs was updated and verified
    to ensure algorithm is working properly even for
    potential interactions for which studies have not
    been conducted

26
Questions?
  • Thank you Genelex!
  • References available upon request
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