10.8 Adjuvant Analgesics
Adjuvant analgesics are medications that were developed for other purposes but were later found to be effective to treat pain. Examples of adjuvant medications include gabapentin (an anticonvulsant) and amitriptyline (a tricyclic antidepressant). Additional information about these specific adjuvant medications can be found in the “Central Nervous System” chapter. Muscle relaxants are also considered an adjuvant analgesic and are used for various musculoskeletal disorders such as multiple sclerosis. Three different types of muscle relaxants will be discussed below: baclofen, cyclobenzaprine, and tizanidine.
Baclofen
Mechanism of Action: Baclofen inhibits reflexes at the spinal level.
Indications: Baclofen is used to treat muscle symptoms, such as spasm, pain, and stiffness, caused by multiple sclerosis, spinal cord injuries, or other spinal cord disorders.
Nursing Considerations: Baclofen is safe for clients 12 years and older.
Side Effects/Adverse Effects: Adverse effects include drowsiness, dizziness or light-headedness, confusion, nausea, constipation, and muscle weakness.
Abrupt Drug Withdrawal: Hallucinations and seizures have occurred on abrupt withdrawal of baclofen. Therefore, except for serious adverse reactions, the dose should be reduced slowly when the drug is discontinued.
Impaired Renal Function: Because baclofen is primarily excreted unchanged through the kidneys, it should be given with caution, and it may be necessary to reduce the dosage.
Signs and symptoms of overdose include vomiting, muscular hypotonia, drowsiness, accommodation disorders of the eye, coma, respiratory depression, and seizures.
Health Teaching & Health Promotion: The medication should be taken as directed and abrupt withdrawal of the medication should be avoided. It may cause dizziness or drowsiness. Clients should be advised to change positions slowly because of the potential orthostatic changes that may occur. Additionally, clients should avoid concurrent use with alcohol or other CNS depressants.[1]
Now let’s take a closer look at the medication grid on baclofen in Table 10.8a.[2],[3]
Table 10.8a Baclofen Medication Grid
| Class/Subclass | Prototype/Generic | Nursing Considerations |
Therapeutic Effects | Side/Adverse Effects |
|---|---|---|---|---|
| Skeletal Muscle Relaxant and Antispasticity Agent | baclofen | Given parentally and orally
Administer orally with milk or food to minimize gastric upset Assess for muscle spasticity before and during therapy Observe for drowsiness For intrathecal administration monitor client closely during test dose and titration and have resuscitative equipment available |
To relieve muscle spasms and spasticity | Drowsiness
Confusion Dizziness or light-headedness Nausea Constipation Muscle weakness |
Critical Thinking Activity 10.8a
A client just started taking baclofen for muscle spasticity due to multiple sclerosis.
What teaching should the nurse provide?
Note: Answers to the Critical Thinking acti