Choosing Pain Meds – Opiates

Purpose of pain = warning the body something is wrong.

Pain is unmeasurable & surrounded by fear culture.

Choosing pain meds based on route. 

• IV: faster onset (only about 5 mins) & lasts 4-6hrs & only available in hospital setting
• IM: variable absorption & good if no IV access
• PO: slower onset (takes about 30 mins to digest) & lasts about 6-8hrs & can prescribe for home

Opiates: bind to 3 main receptors to block pain signals 

• Mu- analgesia, physical dependence, euphoria, resp depression, mast cell degranulation
• Kappa- analgesia, very little dependence, diuresis, dysphoria
• Delta- analgesia, sedation, generally unknown

Opiates are equivalent in their analgesia effects. So how we choose between them? Side effects– its all about the side effects. 

4 effects of opiates you need to know:

• Constipation– opiates decrease gut peristalsis which can lead to bursting the intestines! Write for stool softeners
• Sensitization– chronic blockage of pain receptors lead to increasing the amount of pain receptors present on cells which amplifies even the smallest signal. These patients really  do feel more pain and are less able to handle pain.
• Addiction- two models of thinking: disease model vs psychological. Either way, prevent addiction as much as possible by not giving refills and only prescribing low # of pills for home.
• Withdraw–  As for withdraw, typical opiate withdraw syndrome consists of: sweating, vague abdominal pain, diarrhea.  Withdraw is not fatal. 
• Pseudoallergies– Most ‘allergies’ to opiates are side effects and not real IgE mediated allergies.  If you want to know more here is a really good article on the topic.