"Pain Medications and Pharmacology" is a controversial example of a paper on drug therapy. Pain medication also referred to as analgesic medication is used to relieve and stabilize pain in patients. Pain medication can be grouped in the following classes: opioids, corticosteroids, neurological analgesia, non-steroidal anti-inflammatory drugs, and anesthetic nerve blockade. Pharmacology of Opioids Opioids interact with specific opiate receptors, which include designated kappa, sigma, and mu. The mu receptor is the most significant in terms of respiratory depression and analgesia opioid effects. The mu receptor has two subtypes; mu-1 mediates analgesia and mu-2 mediates the brachychadia, respiratory depression, and physical dependence.
Furthermore, the binding of the opioid agonist to the G protein second messenger leads to the activation of the receptor. This results in the alteration of the membrane permeability by the activated G protein subunits, which increases the permeability of K+ and decreases the permeability of Ca2+. Consequently, the membrane is hyperpolarized; thus, inhibiting neuronal activity (Nagase and Calderon, 2011). The postsynaptic neuron and presynaptic nerve terminal are the two principal sites of actions for the opioids. Opioids' effect on the postsynaptic neuron is inhibitory, while, on the presynaptic nerve terminal, the opioids inhibit the release of neurotransmitters.
The density and location of the opioid receptors on a neuron establishes the general outcome of opioids on the neuron. For example, the action of Morphine on the mu receptors results in the inhibition of some neurotransmitter release such as a neuropeptide, substance P, noradrenaline, and acetylcholine (Freye, 2008). Therapeutic Efficacy of Opioids Nagase and Calderon (2011) state that opioids are effective against chronic pain mostly pain due to cancer. The initial therapeutic efficacy of opioids is highly effective since it has a drastic effect on the pain.
However, this efficacy is not usually maintained over prolonged durations of treatments, despite the increase in dosage and stable pain. The mechanisms that lead to the loss of the therapeutic analgesic effect of the opioids are opioid-induced hyperalgesia, pharmacologic tolerance, and intermittent and subtle withdrawal. Adverse Effects of Opioids The common side effects of opioids include dry mouth, nausea and vomiting, dizziness, drowsiness, and lightheadedness. Headaches, constipation, loss of appetite, weakness or tiredness, visual problems, problems with sleeping, problems with urinating, restlessness and mental sluggishness are the common side effects of opioids.
However, their persistence warrants medical checkups. Opioids can also cause serious side effects, in cases of an overdose. These are bluish coloration of the skin, problems with breathing, cold skin, extremely small pupils, severe drowsiness and dizziness, low blood pressure, confusion, slow heartbeat, and extreme unresponsiveness or sleepiness (Ghodse, 2010). Abuse Potential of Opioids Opioids can be abused by people with chronic pain who have developed an overdependence and tolerance to the drugs. Addiction to drugs significantly increases the probability of its abuse by users.
Diversion of drugs to individuals without prescription to deal with similar pain leads to the abuse of opioids (Freye, 2008). Toxicity of Opioids According to Ghodse (2010), it occurs due to the increase in doses, renal failure, which leads to the failure to excrete opioids and concomitant medical problems, for example, infection and dehydration. Opioid toxicity is life-threatening, and in severe cases, the patients might be comatose and probably have respiratory depression.
Freye, E. (2008). Opioids in Medicine: A Comprehensive Review on the Mode of Action and the Use of Analgesics in Different Clinical Pain States. New York: Springer.
Ghodse, H. (2010). Ghodse’s Drugs and Addictive Behavior: A Guide to Treatment. Cambridge: Cambridge University Press.
Nagase, H., and Calderon, S. (2011). Chemistry of Opioids. New York: Springer