Skeletal Muscle Relaxant include-

Carisprodal, Chlorphenesin Maleate, Chlorzoxazone, Chlormezanone, Cyclobenzaprine, Methocarbinol, Metaxalone, Dantrolenes Sodium, Orphenadrine.

Refer Orphenadrine 

Because of similarity to the TCAs, consider all interactions as tricyclic antidepressants.

Refer amitriptyline.

U.S FDA  APPROVEDDRUGS  FROM 01-01-08 TO 31-12-08

Carisprodal, Chlorphenesin Maleate, Chlorzoxazone, Chlormezanone, Cyclobenzaprine, Methocarbinol, Metaxalone, Dantrolenes Sodium, Orphenadrine.

Refer Orphenadrine

Similar to tricylic antidepressants consider all reactions liste in TCAs-

Refer Amitrityline

Cardiovascular- Tachycardia, syncope, arrhythmias, vasodilation, palpitations, hypotension, chest pain, edema, hypertension, myocardial infarction, heart block.

CNS- Drowsiness, dizziness, fatigue, tiredness, asthenia, blurred vision, headache, nervousness, convulsions, ataxia, vertigo, dysarthria, paresthesia, tremors, hypertonia, malaise, tinnitus, diplopia, decreased or incresed libido, abnormal gait, delusions, peripheral neuropathy,

Bells palsy, alterations in ECG patterns, extrapyramidal synptoms.

Psychiatric : Confusion, disorientation, insomnia, depressed mood, abnormal sensations, anxiety, agitation, abnormal thinking and dreaming, hallucinations, excitement

GI- Dry mouth, nausea, constipation, dyspepsia, unpleasant taste, vomiting, anorexia, diarrhea, GI pain, gastritis, thirst, flatulence, ageusia, paralytic ileus, tongue discoloration, stomatis, parotoid swelling.

GU- Urinary frequency or retension, impaired urination, dilation of urinary tract, impotence, testicular swelling, gynaecomastia, breast enlargement, galoctorrhea.

Hepatic- Abnormal liver function, hepatitis, jaundice, cholestasis,

Dermatologic- Sweating, skin rash, urticaria, pruritus, photosensitizaton, aplopecia

Musculoskeletal : Muscle twitching, local eakness, myalgia

Hematologic/Lymphatic- Purpura, bone marrow depression, leukopenia, eosinophillia, thrombocytopenia.

Metabolic/Nutrional- Elevation and lowering of blood sugar levels, weight gain or loss

Miscellaneous- Edema offace and tongue, inappropiate ADH syndrome, dyspnea

Hypersensitive to cyclobenzapyrine; concomittant use of monoamine(MAO) inhibitors or within 14 days after discontinuation.

Acute recovery phase of myocardial infraction(MI) and in patients with arrhythmias, heart block or conduction disturbances, or congestive heart failure(CHF), hypothyroidism.

Special precautions:

Spasiticty- Cyclobenzapine is not effective in the tretment of spasticity associated with cerebral or spinal cored disease.

Duration- Use only for short periods ( up to 2 to 3 weeks), effectiveness for more prolonged periods not proven.

Similarity to TCAs- cyclobenzaprineis closely related to the TCAs. Because of pharmacologic similarities tricyclic drugs consider withdrawal symptoms with cyclobenzaprine.

Abrupt cessation of treatment after prolongrd administration may produce nausea, headache, and malaise, these do not indicate addiction.

Pregnancy- Use only when clearly needed and when potential benefits outweigh the unknown potential hazards to the fetus.

Lactaion- Excercisecaution when administering cyclobenzaprine to a nursing woman. Children- Safety and eficacy in children < 15 years have not been established

Precautions:

Anticholinergic effects- Use with caution in patients with a history of urinary retension, angle closure glaucoma, and increased intraocular pressure.

Hazradous tasks- May impair mental or physical abilities, requiring performance of hazardous jobs. Patients should observe caution while driving or performing tasks requiring physical dexterity , cordination and alertness.

Indications:

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

Dosage:

Give 10mg 3 times a day(range 20 to 40mg daily in divided doses).

Do not exceed 60mg/day.

Do not use longer than 2 or 3 weeks.

Overdosage- Symptoms

High doses may cause temporary confusion, disturbed concentration, transient visual hallucinations, agitation, hyperactive reflexes, muscle rigidity, vomiting or hyperpyrexia

Overdosage may cause drowsiness, hypothermia, tachycardia and other cardiac arrhythmias, such as bundle branch blcok, ECG evidence of impaired conduction and CHF,dilated pupils, convulsions, severe hypotension, stupor and coma

. Paradoxical diaphorsis has been reported.

Treatment

1. Treatment includes general supportive measures.

2 Obtain ECG and closely monitor cardiac function if there is any evidence of dysrhythmia.

3. Physostigmine 1 to 3 mg IV has been used to reverse anticholinergic effects. However, bradycardia and asytole may occur as a result.

4. The role of physostigmine is not clear,avoid its use if other therapeutic are are unsuccessful in reversing cardiac dysrhythmias.

5.Dilaysis is probably of no value because of low plasma concentrations of the drug.

Missed dose-

1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

Refer Orphenadrine

1.May cause drowsiness, dizziness, or blurred vision. Patients should observe caution while driving or performing tasks requring alertness or coordination, or dexterity.

2. Avoid alcohol and CNS depressants.

3. May cause dry mouth.

Pharmacology:

Cyclobenzapyrine,structurally related to tricyclic antidepressants(TCAs), relieves skeletal muscle spasm of local origin without interfering with muscle function. It is ineffective in muscle spasm due to CNS disease.

Pharmacokinetics: It is well absorbed after oral administration, but there is a large intersubject variation in plasma levels. Peak plasma levels are reached in 4 to 6 hours.

The onset of action occurs in 1 hour with a duration of 12 to 24 hours. It is metabolised and excreted primarily via the kidneys. Elimination half-life is 1 to 3 days.

Pregnancy:

Use only when clearly needed and when the potential benefits outweigh the unknown potential hazards of the fetus.

Lactation:

It is known whether cyclobenzaprine is excreted in breast milk. Excercise caution when administering cyclobenzaprine to a nursing mother. Children: Safety and efficacy in children below 12 years have not been established.