Postoperative analgesics – how I usually prescribe

First, an introduction on analgesics.

What are Analgesics

Analgesics are medicines that are used to relieve pain (provide analgesia). They are also known as painkillers. Technically, the term analgesic refers to a medication that relieves pain without loss of consciousness, as opposed to an anesthetic, which is a substance that induces insensitivity to pain via a loss of consciousness and an absence of sensory perception.

A large number of medicines have pain-relieving properties, and analgesics with similar mechanisms of action are usually grouped together; for example, nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids (narcotics). Analgesics can also be grouped depending on the severity of pain they are indicated for, for example, acetaminophen and NSAIDs are indicated for mild-to-moderate pain, and weak opioids, such as codeine, dihydrocodeine or tramadol are indicated for moderate-to-severe pain.

Central nervous system analgesics act in the brain or spinal cord to produce their effects; examples include opioids such as morphine and oxycodone. Peripherally acting analgesics act outside of the brain and spinal cord and include NSAIDs and COX-2 inhibitors.

https://www.drugs.com/drug-class/analgesics.html


Postoperative analgesics – how I usually prescribe it

Basic Guides

First guide – I determine first how painful or not painful is the postoperative pain usually experienced by patients who undergo a certain operative procedure.  Example, how painful or not painful is pain usually experienced by patients who undergo an excision of an epidermal cyst or lipoma; breast mass excision; mastectomy; thyroidectomy;   cholecystectomy; colon resection; herniorrhapy; hemorrhoidectomy; etc.  If the postoperative pain is usually mild, I usually prescribe a mild analgesics such as paracetamol.  If the postoperative pain is usually moderate, I usually prescribe an analgesic  stronger than paracetamol such as non-steroidal anti-inflammatory drugs such as mefenamic acid.  If the postoperative pain is usually severe, I usually prescribe COX-2 inhibitors or tramadol.

Second guide – I determine the pain threshold of the patient.  If low and patient is too anxious of postoperative pain he/she will experience, I make adjustment on the first guide above.  I give a stronger analgesics.  For example, for postoperative pain that are usually mild, I give mefenamic acid instead of paracetamol.

Other guides

Step-down and step-up analgesic ladder

I usually use the step-down analgesic ladder in managing postoperative pain, meaning starting from the stronger to less strong analgesics, particularly in patients with low pain threshold.

For example, I can start with a COX-2 inhibitor or tramadol then shift to mefenamic acid and then paracetamol as the postoperative days move on in which I expect the pain to decrease.

Another example, in patients undergoing operations under general anesthesia, such as mastectomy and thyroidectomy, I request my anesthesiologist to give one to two doses of parenteral strong analgesics first while patient is in the recovery room and patient cannot take oral analgesics yet.  Once the patient is ready,  I then shift to oral analgesics, either mefenamic acid or paracetamol when patient is in the room depending on the patient’s pain threshold.  In the recovery room, the patients may experience moderate to severe pain as the operation has just been completed.  As time goes by, when the patient is already in the room, say 2-3 hours after the operation, the pain usually decreases. With this and with mastectomy and thyroidectomy wounds usually being associated with mild to moderate pain, a shift to paracetamol or mefenamic acid can be done.  (Side note: circa 2004, in the Department of Surgery of Ospital ng Maynila Medical Center, we did a randomized controlled study comparing paracetamol and mefenamic acid in managing pain of post-mastectomy and post-thyroidectomy patients after an initial dose of parenteral ketoprofen.  Conclusion was that paracetamol can be used in pain control in post-mastectomy and post-thyroidectomy patients as the pain was usually mild.)

Shifting from parenteral analgesics to oral analgesics  

Patients with postoperative wounds that are commonly associated with severe pain are usually given parenteral analgesics.  As postoperative days move on, when the pain is controlled and decreasing already, shift to oral analgesics is in order (that is, if the patients can take oral medications).  I usually add the oral analgesics before the parenteral analgesics are totally discontinued.  If the parenteral analgesics are being given at 6-hour intervals, I usually start the oral analgesics half-way through, meaning 3 hours after the last dose of parenteral analgesic was given.  This is to ensure that there is continued supply of the analgesics in the patient’s bloodstream.

Postoperative pain management after excision of surface lump under local anesthesia and outpatient

I usually ask the patient to bring a paracetamol tablet to the operating room on the day of the excision under local anesthesia.  The assumption is that the postoperative pain is usually mild.  Right after the operation, usually less than one hour, I ask the patient to take the paracetamol tablet.  At home, the patient is advised to take the paracetamol as needed for pain at an interval of at least four hours.  (Commonly observed from my experience is: patients taking the paracetamol at home range from none or zero after the initial intake at the operating room to three tablets.)

Rationality and cost-effectiveness in postoperative analgesic prescription

I tried to do my postoperative analgesic prescription with reason or logic – see basic guides and other guides above.

I also factor in cost-effectiveness – achieving adequate pain control with the least cost.

The other factors that I consider are the past history of allergy to pain medications and potential side effects.


ROJ-TPOR@17sept18

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