Analgesia - APAP, NSAID, Muscle Relaxant Flashcards
NSAID Families
- Carboxylic Acids
- Propionic Acids
- Acetic Acid Derivatives
- Enolic Acids
- Fenamates
- Napthylkanones
Paxton: start with Ibuprofen or Naproxen –> enolic acids –> acetic acid
NSAIDs MOA?
Inhibit COX1 +/- COX2
1 - regulates most normal cellular processes
2 - expressed during inflammation
Reversibly bind platelets, except ASA
What conditions are NSAIDs indicated?
- Analgesia
- Antipyretic
- Dysmenorrhea
- Anti-inflammatory (rheum conditions)
Who are NSAIDs contraindicated in?
Recent CABG
Pregnancy
NSAIDs are pregnancy category ___ because?
Category C
- early: miscarriage
- later: fetal renal dysfunction, premature closure of PDA
General side effects/ risks of NSAIDs?
- GI, CV, Renal
- Caution w/HTN, HF, CKD, asthma
- May precipitate asthma and anaphylactoid reaction in ASA-sensitive pt (not IgE-mediated)
Describe the GI side effects related to NSAIDs?
- Dyspepsia/gastritis & ulceration/perforation*
- INC r/o GI bleed w/anti-plt, EtOH, steroids
- may exacerbate IBD
Describe the CV side effects related to NSAIDs?
- r/o thrombosis [BBW INC r/o CV events]
- d/c ALL (except ASA) in AMI pt
- caution w/warfarin
- reversible plt dysfunction –> INC bleeding time
- may interfere w/anti-plt effect of ASA (try other analgesics first)
Describe the renal side effects related to NSAIDs?
- DEC efficacy of diuretics (loops/thiazides & ACE/ARB) –> AKI risk
- INC [Li]
- nephrotoxicity: fluid retention, AIN, ATN
Who must you avoid NSAIDs in?
Pt with high GI and CV risk
Your elderly patient is on diuretics and ACE/ARB. You need to start him on NSAIDs now too. What must you monitor?
Monitor renal function and serum K within 7 days of starting the NSAID
Recognize Carboxylic Acids
- ASA*
- Salsalate
- Diflunisal
- Choline Mag Trisalicylate
Recognize Propionic Acids
- Ibuprofen*
- Naproxen*
- Fenoprofen
- Ketoprofen
- Flurbiprofen
- Oxaprozin
Recognize Acetic Acid Derivatives
- Indomethacin*
- Diclofenac*
- Ketorolac*
- Sulindac
- Etodolac
- Tolmetin
Recognize Enolic Acids
- Piroxicam (better CV, worse GI)
2. Meloxicam (worse CV, better GI)
Which NSAID is safest for breastfeeding women? It also has low GI toxicity.
Ibuprofen
Which NSAID is safest in terms of CV toxicity?
Naproxen
Which propionic acid has more GI toxicity, ibuprofen or naproxen?
Naproxen
Which acetic acid is used for PDA closure? Give it to the baby, but don’t give to pregnant women!
Indomethacin (IV for PDA closure)
What are two side effects of Indomethacin?
- worst GI toxicity
- high r/o thrombosis
Acetaminophen max dose
- 1,000 mg/dose
- 4g/day
Acetaminophen indications
- Antipyresis
- Mild-mod pain –> IV APAP more robust that PO
Acetaminophen MOA
- Not clear
- Analgesia: Inhibit NO pathway mediated by certain NTs
- Antipyretic: inhibits endogenous pyrogens
Acetaminophen ADRs
-Hepatotoxicity (inc glutathione–> acetylimidoquinone)
- > 3 drinks/day + APAP
- > 4g/day (50% unintentional, iatrogenic)
- Additive effect if given with =/> 1 hepatotoxic med (INH, etc)
Acetaminophen Hepatotox tx
Acetylcysteine- given within 8-10 hr of OD
Acetaminophen and Pregnancy
- Category C
- Occasional use is fine for mild-mod pain
Prescribing APAP
-put max tabs/day in sig to help keep patients from going over 4g/day
Cyclobrenzapine
- MOA: near identical to amitriptyline
- Indications: SHORT-TERM (2-3 wks) muscle spasms–> has most evidence for efficacy
- Interactions: death with CNS depressants, don’t give 14d of MAOI, seizure reported with tramadol
- CI in pts with arrhythmia, AMI, HF
- ADRs: sedation, dizziness, xerostomia quinidine-like effect (QT-prolongation)**
Carisoprodol
- MOA: unknown
- Indication: don’t use according to MISTER Paxton
- Schedule IV drug
- Interactions: additive sedation with CNS depressants
- ADRs: dizziness/sedation, transient quadriplegia, temporary loss of vision**
Baclofen
- Indications: SC injury/MS
- Withdrawal sx or worsening spasticity if not tapered over 2 wks
Dantrolene
- Spasticity in BS or SC injury
- Also used for malignant hyperthermia (IV)
ADR: dose-dependent hepatotoxicity
You should avoid this acetic acid derivative at all costs, due to toxicity, especially with CV events. What are the other side effects?
Diclofenac
CV events; greatest r/o thrombosis
Increased HTX (dili drug) Increased GI tox
Your patient requires a pain med. Which potent NSAID could you give IV. You must limit IV/IM to less than 5 days otherwise there is increased risk of ____.
Ketorolac
AKI > 5d
3 drugs to minimize GI side effects of NSAIDs. Which is preferred?
- Misoprostol
- H2Ras (famotidine)
- PPIs (omeprazole)**
Misoprostol is a progesterone analogue used to prevent gastric ulcers. Know these other two things:
- SE: diarrhea
- Cat X (abortion)
What’s the 1 Cox-2 selective NSAID still on market?
Celecoxib
What’s the main use of Cox-2 inhibitors?
Anti-inflammatory for rheum
AE:
- less GI toxicity
- nephrotoxicity
Which drugs are used for MS, SC injury?
Antispastics
- baclofen
- dantrolene
Which muscle relaxants are used for other msk conditions?
Antispasmodics
- cyclobenzaprine*
- carisoprodol*
- metaxalone
- methocarbamol
- chlorzoxazone
- tizanidine
- orphenadrine
