Ocular pain management presents with various treatment options

December 1, 2009

There are a number of therapeutic options for mitigating ocular pain, but proper diagnosis of the underlying cause is the first principle in appropriate pain management.

"Pain is a symptom, not a disease, and while it is imperative to manage ocular pain, it must be done within the context of the cause, which may be inflammation, infection, injury, or ischemia," said Dr. Onofrey, professor, University of Houston.

Whether the goal is to provide analgesia alone, control of inflammation, or both, pharmacologic activities will drive the choice of pharmacotherapy. Other factors that are taken into account in selecting a specific agent include the expected duration of treatment and the patient's medical history, since there are a number of contraindications to consider for each class of medications.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are cyclooxygenase inhibitors that mitigate pain by blocking the production of prostaglandins. Used at higher doses, NSAIDs also provide anti-inflammatory activity, albeit with increased risk of side effects, and they have antipyretic properties as well.

While a number of different oral NSAIDs are available, when used at equipotent doses, they all provide the same benefit because they work via the same mechanism of action. These agents differ only in their potency and elimination half-life, which determine the recommended dose and frequency of administration. For example, ibuprofen 600 to 800 mg Q.I.D. is equivalent to naproxen sodium 375 mg B.I.D. or piroxicam 20 mg Q.D.

"Piroxicam offers the convenience of once daily dosing, but ibuprofen enables more flexible dosing strategies," Dr. Onofrey said.

While NSAIDs have a relatively favorable safety profile, they should be avoided in patients with diabetes, gastric or duodenal ulcers, renal insufficiency, congestive heart failure, pregnant and lactating women, and in persons who are on anticoagulant therapy. Patients allergic to aspirin or any NSAID will be allergic to all NSAIDS, and the risk of an NSAID allergy is also increased in asthmatics and patients with nasal polyps. Aspirin should be avoided in children with fever and pregnant patients.

Opiates

Opiates are pure analgesics that act by blocking CNS mu receptors to reduce the perception of pain.

They can be a reasonable choice for patients whose pain is too severe to be controlled by acetaminophen or an NSAID alone or for those with a contraindication to acetaminophen or an NSAID, recognizing that opiate combinations containing acetaminophen or aspirin must also be avoided in patients with a contraindication to any of the ingredients. Patients who report allergy to one opiate will be also be allergic to all, Dr. Onofrey noted.

Sedation is a side effect of opiates, but may be desirable for some patients. Other common side effects include urinary retention, constipation, respiratory depression, and nausea and vomiting. Addiction and abuse potential are the well-known drawbacks of prescribing opiate analgesics.

"Know the Drug Enforcement Administration schedule for the various narcotic analgesics, and be aware that while tramadol (Ultram, Ortho-McNeil), an opiate derivative which also acts on the CNS mu receptors, has been touted for not having opiate side effects, it has produced addiction and should also be avoided in patients with an opiate allergy," Dr. Onofrey said.

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