| ORPHENADRINE CITRATE
Classifications: skeletal muscle relaxant, central acting; Therapeutic: skeletal muscle relaxant, central acting
Pregnancy Category: C
100 mg sustained release tablets; 30 mg/mL injection
Tertiary amine anticholinergic agent and central-acting skeletal muscle relaxant. Relaxes tense skeletal muscles indirectly,
possibly by analgesic action or by atropinelike central action.
Relieves skeletal muscle spasm.
To relieve muscle spasm discomfort associated with acute musculoskeletal conditions.
Narrow-angle glaucoma; pyloric or duodenal obstruction, stenosing peptic ulcers; prostatic hypertrophy or bladder neck obstruction;
myasthenia gravis; cardiospasm (megaloesophagus); tachycardia; pregnancy (category C). Safe use in the pediatric age group
is not established.
History of cardiac disease, arrhythmias, coronary insufficiency; renal disease; renal impairment; lactation.
Route & Dosage
Adult: PO 100 mg b.i.d. IM/IV 60 mg, may repeat in 12 h if needed
- Ensure that sustained release form is not chewed or crushed. It must be swallowed whole.
PREPARE: Direct: Give undiluted. Protect from light.
ADMINISTER: Direct: Give at a rate of 60 mg (2 mL) over 5 min with patient in supine position. Keep supine for 510 min post-injection.
Adverse Effects (≥1%)CNS: Drowsiness,
weakness, headache, dizziness; mild CNS
stimulation (high doses: restlessness, anxiety, tremors, confusion, hallucinations,
agitation, tachycardia, palpitation, syncope). Special Senses:
tension, dilated pupils, blurred vision. GI: Dry mouth,
nausea, vomiting, abdominal cramps, constipation
. Urogenital: Urinary hesitancy
. Body as a Whole:
Hypersensitivity [pruritus, urticaria, rash, anaphylactic reaction
may cause increased confusion, anxiety, and tremors; may worsen schizophrenic symptoms
, or increase risk of tardive dyskinesia
depressant with anxiolytics
, butorphanol, nalbuphine, opiate agonists
, pentazocine, tramadol. Herbal: Valerian, kava
Readily from GI tract. Peak:
2 h. Duration:
46 h. Distribution:
Rapidly distributed in tissues; crosses placenta. Metabolism:
In liver. Elimination:
In urine. Half-Life:
Assessment & Drug Effects
- Lab tests: Periodic blood, urine, and liver function studies with prolonged therapy.
- Report complaints of mouth dryness, urinary hesitancy or retention, headache, tremors, GI problems, palpitation, or rapid
pulse to physician. Dosage reduction or drug withdrawal is indicated.
- Monitor elimination patterns. Older adults are particularly sensitive to anticholinergic effects (urinary hesitancy, constipation);
- Monitor therapeutic drug effect. In the patient with parkinsonism, orphenadrine reduces muscular rigidity but has little
effect on tremors. Some reduction in excessive salivation and perspiration may occur, and patient may appear mildly euphoric.
Patient & Family Education
- Relieve mouth dryness by frequent rinsing with clear tepid water, increasing noncaloric fluid intake, sugarless gum, or
lemon drops. If these measures fail, a saliva substitute may help.
- Do not drive or engage in potentially hazardous activities until response to drug is known.
- Avoid concomitant use of alcohol and other CNS depressants; these may potentiate depressant effects.