Muscles, Ligaments and Tendons Flashcards
What is contained within robaxacet?
acetaminophen and methocarbamol
What is contained in robaxisal?
ASA and methocarbamol
What is contained within robax platinum?
ibuprofen and methocarbamol
What products is chlorzoxazone in?
- parafon forte, tylenol aches and strains and acetazone
What products is orphenadrine in?
- solo or in combination - norflex (mainly over the counter)
What is methocarbamol?
central acting skeletal muscle relaxant , but does not work directly on the contractile mechanism of the striated muscle, motor endplate or nerve fiber
What is the MOA of methocarbamol?
unknown, but it is thought to cause skeletal muscle relaxation due to general CNS depression
What is methocarbamol used to treat?
- used to treat acute, painful, musculoskeletal muscle spasms
What is the onset of action of methocarbamol?
12-24 hours
What is the MOA of orphenadrine?
- works by mechanisms related to analgesic and anti-cholinergic properties Exact mechanism of action have not been determined
What is orphenadrine used to treat?
- used to treat painful muscle spasm due to acute musculoskeletal conditions
What is the onset of orphenadrine?
24 hours
What is the mechanism of chlorzoxazone?
- muscle relaxant due to its central acting properties
- does not act directly on the muscles, but it works on the spinal cord and brain level to decrease skeletal muscle spasm, provide pain relief and increase mobility of the muscle
What is the main SE of chlorzoxazone?
hepatotoxicity
What is the onset of cholzoxazone?
within 12-24 hours
What are the main SE of methocarbamol?
- drowsiness, dizziness, light headedness, headaches, urine discolouration (black, blue, green or brown)
What are the main SE of orphenadrine?
CNS SE, constipation, dry mouth and blurred vision
What are the main SE of chlorzoxazone?
CNS SE, urine discoloration (orange-red), impaired hepatic function
What are the main contraindications of skeletal muscle relaxants?
- pregnancy, anticholinergic activity, narrow angle glaucoma, prostate hypertrophy, arrhythmias
What are the drug interactions associated with skeletal muscle relaxants?
- other Ach agents, CNS depressants, MAO inhibitors, increase CNS AE, alcohol
What are the effects that topical analgesics exert?
- analgesic effects (raise pain threshold at terminal nerve ending)
- anesthetic (block pain receptors to numb the area)
- antipruritic (relieve itching)
- counterirritant effects (stimulate cutaneous sensory receptors)
What is an counterirritant?
a substance that is rubbed into the skin over a painful joint, tendon, ligament or muscle to relieve pain
- other agents are often needed as an adjuvant (oral analgesics, support bandages, rest, ice compression)
When are counterirritants of particular use?
- for patients that cannot tolerate AE associated with other oral analgesics
What is the MOA of counterirritants?
- paradoxical pain- relieving effect achieved by producing a less severe pain to counter a more intense one
- produces mild, local inflammatory reaction. Does this by producing redness (methyl salicylate, turpentine oil, strong ammonia solution), by producing a rolling effect (camphor and menthol), by vasodilation (methyl nicotinate)
- there can also be a placebo effect associated with a counterirritant (pleasant warmess, coolness or smell associated)
What causes the feeling of warmth in a topical agent?
- methyl salicylate, capsaicin, trolamine salicylate
What causes the feeling of cold from an analgesic?
- menthol or camphor
What is a “ no odour” product contain?
- do not have wintergreen oil or camphor
- instead have trolamine salicylate
What are the pieces of precautionary advice that we should be giving about external analgesics?
- external use only
- do not apply to wounds
- do not bandage
- avoid contact with the eyes
- not to be used in children less then 2
- not to be used more than tid or qid
- do not apply heat or other thermotherapy device concurrently with counterirritants
When should the use of methyl salicylate or trolamine salicylate be avoided?
- should be avoided when taking anticoagulants
- when allergic to salicylate
- caution should be exercised for salicylate sensitive asthmatics
What are the clinical considerations of using an external analgesic?
- lack scientific evidence
- few studies suggest a high placebo component here (due to subjective nature of pain)
- massaging aspect may be an important component of efficacy
- desired effect local vs systemic
- no rationale exists for combining the use of more than one counterirritant product
- 7 days of use is reasonable length of time for most products, except capsaicin
- topical analgesic does not alter the underlying process
- may be helpful with symptomatic relief or distraction
What is the MOA of using capsaicin?
- when applied produces a transient feeling of warmth, but diminishes with repeated applications (tachyphylaxis)
- due to depletion of substance P (a chemical that allows the transmission of pain impulses) in sensory neurons
- reduces pain but not inflammation
- pain is usually relieved within 14 days, but occasionally delayed by 4-6 weeks
- may be beneficial in OA pain, postherapeutic neuralgia and lower back pain
- do not use on wounds or damaged skin
Anytime a pain signal happens, there is a release of the product known as ____
substance P - takes a long time to deplete the substance P
Capsaicin needs to be applied ______
3x a day (needs to do this to provide optimal pain relief and may cause initial burning sensation to persist)