Carisoprodol [Soma]1
350 mg four times daily
Not recommended for children younger than 12 years
Dizziness, drowsiness, headache
Rare idiosyncratic reactions [mental status changes, transient quadriplegia, and temporary loss of vision] after first dose; may require hospitalization
Allergy-type reactions may occur after the first to fourth dose; may be mild [e.g., cutaneous rash] or more severe [e.g., asthma attack, angioneurotic edema, hypotension, or anaphylactic shock]; antihistamines, epinephrine, or corticosteroids may be needed
Physical or psychological dependence may occur; withdrawal symptoms may occur with discontinuation
Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants
Contraindicated in acute intermittent porphyria
FDA pregnancy category C
$72 to $100 [generic]
$590 [brand]
Chlorzoxazone [Parafon Forte]2
Adults: 250 to 750 mg three to four times daily
Children: 125 to 500 mg three to four times daily; or 20 mg per kg daily in three or four divided doses
Dizziness, drowsiness
Red or orange urine
GI irritation and rare GI bleeding
Hepatoxicity [rare]; discontinue with elevated liver function test
Avoid use in patients with hepatic impairment
Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants
FDA pregnancy category C
15 to 77 [generic]
180 [brand]
Cyclobenzaprine [Flexeril]3
5 mg three times daily; may increase to 10 mg three times daily
Anticholinergic effect [drowsiness, dry mouth, urinary retention, increased intraocular pressure]
Rare but serious adverse effects are arrhythmias, seizures, myocardial infarction
Most studied skeletal muscle relaxant
120 to 140 [generic]
157 [brand]
Long elimination half-life
5-mg dose as effective as 10-mg, with fewer adverse effects
Avoid in older patients and in patients with glaucoma
Possible drug interaction with CYP450 inhibitors
Seizures reported with concomitant use of tramadol [Ultram]; combination should be avoided in patients with medical conditions that may induce seizures
Contraindicated in patients with arrhythmias, recent myocardial infarction, or congestive heart failure
FDA pregnancy category B
Diazepam [Valium]4
Adults: 2 to 10 mg three to four times daily
Children: 0.12 to 0.80 mg per kg daily in three or four divided doses
Dizziness, drowsiness, confusion
Abuse potential
Also an antispastic agent
11 to 23 [generic]
184 [brand]
Long elimination half-life; avoid in older patients and in patients with hepatic impairment
Possible drug interaction with CYP450 inhibitors
Complete blood count and liver function tests indicated for prolonged use
FDA pregnancy category D; avoid especially in the first trimester
Metaxalone [Skelaxin]5
800 mg three to four times daily
Not recommended in children younger than 12 years
Drowsiness, dizziness, headache, nervousness
Leukopenia or hemolytic anemia [rare]
Liver function test elevation [rare]
Nausea, vomiting, and diarrhea [rare]
Paradoxical muscle cramps
Use with caution in patients with liver failure
Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants
Less dizziness and drowsiness than other skeletal muscle relaxants
FDA pregnancy category C
275; generic not available
Methocarbamol [Robaxin]6
1,500 mg four times daily for first two to three days, followed by 750 mg four times daily
Black, brown, or green urine possible
Mental status impairment
Possible exacerbation of myasthenia gravis symptoms
Possible respiratory depression when combined with benzodiazepines, barbiturates, codeine or its derivatives, or other muscle relaxants
FDA pregnancy category C; reports of fetal abnormalities
15 to 58 [generic]
176 [brand]
Orphenadrine [Norflex]7
100 mg twice daily
Combination products are dosed three to four times daily
Anticholinergic effect [drowsiness, dry mouth, urinary retention, increased intraocular pressure]
Aplastic anemia [rare]
GI irritation
Confusion, tachycardia, hypersensitivity reaction [with high doses]
Long elimination half-life
110 to 140 [generic]
162 [brand]
Reduced dosages in older patients
Avoid in patients with glaucoma, cardiospasm, or myasthenia gravis
Decreases effect of phenothiazines [e.g., chlorpromazine [Thorazine†], promethazine [Phenergan]]
FDA pregnancy category C
Tizanidine [Zanaflex]8,9
4 mg initially; may increase by 2 to 4 mg every six to eight hours until relief
Do not exceed 36 mg daily
Dose-related hypotension, sedation, and dry mouth
Hepatotoxicity; monitor liver function tests at baseline and one, three, and six months
Withdrawal and rebound hypertension may occur in patients discontinuing therapy after receiving high doses for long period of time; tapering is recommended
Also antispastic agent
329 [generic]
437 [brand]
Do not use with CYP1A2 inhibitors, ciprofloxacin [Cipro] or fluvoxamine [Luvox CR]
Caution with CYP1A2 inhibitors, central nervous system depressants, or alcohol
Decreased effectiveness with oral contraceptives
FDA pregnancy category C
Which conditions are contraindications to the administration of barbiturates select all that apply
Contraindications: Barbiturate sensitivity, liver disease, impaired renal function, patients with severe respiratory distress, respiratory disease in which dyspnea, obstruction or cor pulmonale is present, acute or chronic pain.
Barbiturates are central nervous system depressants and should not be taken with alcohol or other drugs that slow the central nervous system, such as antihistamines, cold and allergy medicines, sleep medications, tranquilizers, medicine for seizures, narcotics, and muscle relaxants.
A medicine called naloxone [Narcan] may be given if an opiate was part of the mix. This medicine often rapidly restores consciousness and breathing, but its action is short-lived, and may need to be given repeatedly.
Barbiturates are a group of sedative-hypnotic medications used for the treatment of seizure disorder, neonatal withdrawal, insomnia, preoperative anxiety, induction of coma for increased intracranial pressure. They are also useful for inducing anesthesia.