Question

1. Discuss 5 classes of medications used for acute pain and the nursing responsibilities for each.

2. Discuss 5 classes of medications used for chronic pain and the nursing responsibilities for each.

Answer 1

Question 1

Classes of drugs used for acute pain include:-

-Acetaminophen

Also called paracetamol. Acts by inhibiting a third cycloxygenase pathway which is activated by an enzyme present in brain and spinal cord. Rapidly absorbed orally.Peak plasma concentrations occur in 30 minutes to 2 hours.It is rapidly eliminated.Gastrointestinal adverse effects are less.Over dosage causes liver damage

Nursing considerations:- Total adult dose shouldn't exceed 1000mg sixth hourly.Paracetamol may be present as an ingredient in decongestant cold and flu remedies. This should be considered while administering paracetamol, so that overdosage shouldn't occur

-Nonsteroidal anti inflammatory drugs

They act by blocking the production of prostaglandins.Prostaglandins are produced through cycloxygenase pathway. These drugs block the cycloxygenase enzymes. Adverse effects occur with gastrointestinal system and kidneys.Aspirin and ibuprofen comes under this group.Aspirin is better absorbed in an acidic environment.Both the drugs are given with or after food in an enteric coated form to prevent gastrointestinal erosions and ulcers.Adverse effects of aspirin include peptic ulcers ,gastrointestinal bleeding.Ibuprofen also has similar adverse effects. Also diarrhea, nausea etc are seen.

Nursing considerations :-Caution is needed while using aspirin in asthmatic patients, because it can precipitate an acute exacerbation.Aspirin is avoided in children because of the risk of getting Reye's syndrome.Ibuprofen shouldn't be combined with drugs such as lithium, gentamicin.Blood levels of these drugs will be raised due to interaction with ibuprofen. Also,it should be avoided in pregnancy

-Opioid analgesics

Used in moderate to severe pain.Acts by binding to opioid receptors in central nervous system. They mimic our own endorphins a and have similar analgesic action.They have antitussive and anti diarrhoeal action also.Natural drugs include morphine and codeine.Synthetic ones are diamorphine,fentanyl,meperidine and methadone.Morphine acts by blocking the opening of calcium channels in neurons so that pain signals are not transmitted .Also it cause hyperpolarization by opening potassium channels and making the inside negative.

Nursing considerations:- Morphine can cause respiratory depression and pupillary constriction.Pupillary constriction is hence considered as diagnostic of opioid over dosage, because other causes of unconsciousness makes pupil dilate

-Muscle relaxants

Used in the setting of muscle spasm.They act on brain and spinal cord to reverse excess stimulation in neuronal pathways.They relieve muscle tension.Eg:- baclofen,tizanidine

Nursing consideration:- They cause drowsiness,dizziness,headache,weakness etc.Hence patients should be advised to keep away from driving.

-Local anaesthetics

Acts by blocking sodium channels.Blocks the conduction of nerve impulses better in small diameter fibres is,A delta and C fibres.Used as local application before minor surgical procedures.It causes vasodilation and may result in rapid absorption of the drug which will reduce its effects.Hence it is usually combined with vasoconstrictor adrenaline Eg :- lignocaine,EMLA cream in children before insertion of cannula

Nursing considerations:- Adrenaline shouldn't be used in infiltration ain toe blocks because vasoconstriction will produce ischemia

Question 2

Classes of drugs used for chronic pain include:-

-Antidepressants

Antidepressants such as tricyclic antidepressants (nortryptilline ,desipramine) are used to relieve chronic neuropathic pain such as post herpetic neuralgia, tension headache, fibromyalgia, chronic low back ache etc.

Nursing considerations:-Side effects such as urinary retention, hypotension,drowsiness,constipation can occur

-Anticonvulsant

Phenytoin, Carbamazepine are used to treat the shooting pain of trigeminal neuralgia. Also the newer drug pregabalin is also found to be effective ,with less side effects

Nursing considerations:-Blood levels of phenytoin need to be monitored. Drowsiness, ataxia,slurred speech,increased hair growth and acne can be seen as adverse effects

-Local anaesthetics and antiarrhythmics

Following neuronal injury,the neuronal sprouts produce electrical discharges which cause pain.Local anesthetic agents and antiarrhythmic agents can be tried.Examples are lidocaine and mexiletine.

Nursing considerations:- Mexiletine may cause adverse effects such as worsening of existing arrhythmias and tremor.

-Non steroidal anti inflammatory drugs

-Opioids