Musculoskeletal conditions

The mode of action of many skeletal muscle relaxants, for example carisoprodol (Soma), baclofen (Lioresal), and chlorzoxazone (Paraflex), is not clearly understood. Many of tiiese dragp do not directly relax skeletal muscles, but dieir ability to relieve acute painful musculoskeletal conditions may be due to their sedative action. Cyclobenzaprine (Flexeril) appears to have an effect on muscle tone, tiius reducing muscle spasm. 

The exact mode of action of diazepam (Valium), an antianxiety drug (see Chap. 30), in die relief of painful musculoskeletal conditions is unknown. The drug does have a sedative action, which may account for some of its ability to relieve muscle spasm and pain. 

Skeletal muscle relaxants are used in various acute, painful musculoskeletal conditions, such as muscle strains and back pain. 

Promoting an Optimal Response to Therapy The patient with a musculoskeletal disorder may be in acute pain or have longstanding mild to moderate pain, which can be just as difficult to tolerate as severe pain. Along with pain, there may be skeletal deformities, such as the joint deformities seen with advanced rheumatoid arthritis. For many musculoskeletal conditions, drug therapy is a major treatment modality. Therapy with these drugs may keep the disorder under control (eg, therapy for gout), improve the patient s ability to carry out the activities of daily living, or make the pain and discomfort tolerable. 

Rubefacients act by counter-irritation produced as a result of local vasodilation, resulting in a warm sensation that masks the pain. Counter-irritants should not be applied on broken skin or before or after taking a hot shower. Examples of counter-irritants include salicylates, nicotinates, capsicum, menthol and camphor. Ketoprofen is an example of a non-steroidal anti-inflammatory drug that is available as a topical preparation indicated in painful musculoskeletal conditions. 

Musculoskeletal conditions Adjunct to rest and physical therapy for relief of muscle spasm associated with acute painful musculoskeletal conditions. 

Similarity to TCAs Cyclobenzaprine is closely related to the TCAs. In short-term studies for indications other than muscle spasm associated with acute musculoskeletal conditions, and usually at doses greater than those recommended, some of the more serious CNS reactions noted with the TCAs have occurred. Pregnancy Category B. 

Methocarbamol (Robaxin) [Skeletal Muscle Relaxant/ Centrally Acting] Uses Relief of discomfort associated w/ painful musculoskeletal conditions Action Centrally acting skeletal muscle relaxant Dose Adults. 1.5 g PO qid for 2-3 d, then 1-g PO qid maint therapy IV form rarely indicated Peds. 15 mg/kg/dose IV, may repeat PRN (OK for tetanus only), max 1.8 g/mVd for 3 d Caution Sz disorders [C, +] Contra MyG, renal impair Disp Tabs, inj SE Can discolor urine drowsiness, GI upset Interactions T Effects Wf CNS depressant, EtOH EMS May cause blurred vision and orthostatic hypotension use caution w/ CNS depressants concurrent EtOH use can T CNS depression OD May cause drowsiness, light-headedness, syncope, and slow shallow breathing symptomatic and supportive... 

Adjunct to rest, physical therapy, analgesics, and other measures for relief of discomfort from acute, painful musculoskeletal conditions PO 350 mg4 times a day. Use lower initial dose and increase gradually as needed and tolerated in patients with hepatic dis-... 

Phenylbutazone, the major suxibuzone metabolite, has been approved by the FDA for use in dogs and horses (87). It is not licensed in cattle but its properties make it useful in this species for the treatment of musculoskeletal conditions, mastitis, endotoxemia, and castration. Since there is evidence of extralabel use for treatment of mastitis in lactating cows, residues of this drug may be found in bovine milk. 

Chlorzoxazone (Paraflex, Parafon Forte DSC, Others) [Skeletal Muscle Relaxant/ANS Drug] Uses Adjunct to rest physical therapy to relieve discomfort associated w/ acute, painful musculoskeletal conditions Action Centrally acting skeletal muscle relaxant Dose Adults. 250-500 mg PO tid-qid Peds. 20 mg/kg/d in 3-4 + doses Caution [C, ] Avoid EtOH CNS depressants Contra Severe liver Dz Disp Tabs SE Drowsiness, tach, dizziness, hepatotox, angioedema Interactions T Effects W/ antihistamines, CNS depressants, MAOIs, TCAs, opiates, EtOH, watercress EMS Use of CNS depressants and concurrent EtOH use can T sedation urine may turn reddish purple or orange OD May cause N/V/D, dizziness, HA, X deep tendon reflexes, hypotension and resp depression symptomatic and supportive, activated charcoal may be effective... 

Finally, local anesthetics can be administered via a transdermal patch.1 In particular, transdermal patches containing 5% lidocaine have been used to treat localized pain in musculoskeletal conditions (osteoarthritis, low back pain, myofascial pain)22,25,26 and various types of neuropathic pain (postherpetic neuralgia, diabetic neuropathy).2,24,58 As indicated in Chapter 2, transdermal patches provide a convenient and predictable method for administering drugs to a given anatomical site, and lidocaine patches are now being used to provide symptomatic relief in many conditions involving fairly localized pain. 

Consequently, polysynaptic inhibitors can help provide short-term relief for muscle spasms associated with certain musculoskeletal conditions, and they may work synergistically with physical therapy and other interventions during acute episodes of back pain, neck pain, and so forth. Nonetheless, they have some rather serious side effects and potential for abuse, and the long-term use of these drugs should be discouraged. 

Beebe FA, Barkin RL, Barkin S. A Clinical and Pharmacologic Review of Skeletal Muscle Relaxants for Musculoskeletal Conditions. Am J Ther. 2005 12 151-171. 

Chou R, Peterson K, Helfand M. Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions a systematic review. J Pain Symptom Manage. 2004 28 140-175. 

Tehranzadeh J, Ter-Oganesyan RR, Steinbach LS. Musculoskeletal disorders associated with HIV infection and AIDS. Part II non-infectious musculoskeletal conditions. Skeletal Radiol. 2004 33 311-320. 

Praemer, A., Furner, S., and Rice, S. D., Musculoskeletal Conditions in the United States. American Academy of Orthopaedic Surgery, Park Ridge, IL, 1992. 

Anti-inflammatory action this is utilised in all t5 es of arthritis, musculoskeletal conditions and pericarditis. 

In humans, phenylbutazone therapy has been associated with bone marrow dyscrasias, such as agranulocytosis and aplastic anemia (Flower et al 1985). Care should be taken when handling the product to prevent human exposure. The use of phenylbutazone in horses has been banned in many European countries because of concerns for human health and because the horse is considered a food animal under European law. Nevertheless, it is still prescribed very commonly for musculoskeletal conditions in the USA and the UK. It is interesting to note that there is only one report in the literature of bone marrow suppression occurring with phenylbutazone therapy in a horse and in that case very high doses of the agent had been administered (Murray 1985). 

Trade names Banflex (Forest) Biorfen Biorphen Disipal Distalene Flexojet Flexon Myolin Norflex (3M) Norgesic Opheryl Orfenace Prolongatum Indications Painful musculoskeletal conditions Category Central muscle relaxant Muscarinic antagonist Half-life 14 hours... 

Only a small proportion of an NSAID penetrates through the skin, but once absorbed it shows a strong affinity for tissues. Clinical evidence indicates that topical NSAIDs are effective over short periods for musculoskeletal conditions, are as effective as oral NSAIDs and have a very low incidence of adverse effects. 

Woolf AD Pfleger B (2003) Burden of major musculoskeletal conditions. Bull World Health Organ, 81 646-656. 

Carisoprodol is a centrally acting skeletal muscle relaxant. It is indicated as an adjunctive treatment for acute, painful musculoskeletal conditions (e.g., muscle strain). Carisoprodol (350 mg p.o. t.i.d.) is indicated as an adjunct to physical therapy in acute painful musculoskeletal conditions. It causes muscular relaxation by blocking interneuronal... 

Chlorphenesine (400 to 800 mg t.i.d.) is indicated as an adjunct to rest and physical therapy for the relief of discomfort associated with acute and painful musculoskeletal conditions. Chlorphenesine-induced muscular relaxation may be related to its sedative properties because it does not exert its effects either directly on skeletal muscles or myoneural junctions. 

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