Opiates are some of the most addictive and abused substances available today. They include illegal derivatives like heroin and opium in addition to legal therapeutics for pain like morphine and fentanyl. Their abuse can result in various side effects that seriously affect the body.
Pupil Size
Opiate substances tend to constrict the pupil of the eye via actions on the parasympathetic nerves that provide input to the eye. Tolerance to this doesn't develop, which is why physicians often look at the pupils of someone with an altered mental state; often the presence of constricted pupils can hint at possible opiate abuse.
Effects on the Respiratory System
These side effects tend to be some of the most severe effects of opiate abuse. Opiates tend to depress the respiratory system via actions on the brainstem that regulate breathing rhythm and drive. This effect is dependent on dose and is the primary method of death in opiate overdose.
Effects on the Cardiovascular System
The dominant effect of opiates on the heart is to decrease heart rate, which is known as bradycardia. It can also cause certain body cells to release a chemical known as histamine; this results in dilation of the blood vessels and can result in lower blood pressure (also known as hypotension).
Effects on the Gastrointestinal System
Opiates tend to decrease the motility of the gastrointestinal tract, which is one of the reasons they are used as anti-diarrhea medications (such as Immodium for example). They can also cause spasm of the gallbladder duct, which results in possible extraneous release of bile from the gall bladder. Nausea and vomiting is also common, resulting both from delayed emptying of the stomach contents and from direct actions on brain vomiting centers. Constipation is also one of the most common effects of opiate abuse, and tolerance to the constipating effect does not develop.
Tolerance
Opiate users develop tolerance--the effect where increasing doses of the substance needs to be ingested to produce the same effect. Their effects on reducing pain and inducing a euphoric state tend to be more prone to tolerance, while effects such as constricted pupils and depression of the respiratory system tend to persist. This is the mechanism by which overdose can occur as more and more of the drug is ingested with less effects occurring, except the toxic ones.
Addiction
This can refer to both physical and mental addiction. Mental addiction refers to the constant perceived need for opiate ingestion and can cause the patient mental anguish and cause them to undertake uncharacteristic behavior to obtain the substance (such as theft, prostitution or lying). Physical addiction refers to the symptoms that occur when substance abstinence is undertaken. This is known as withdrawal and in the case of opiates includes a host of symptoms such as vomiting, diarrhea and anxiety, among others.
References
- "Miller's Anesthesia, 7th Edition;" Miller; 2009
- "Palliative Medicine, 1st Edition;" Walsh; 2008
- Medical Clinics of North America. "Opioid Tolerance and Hyperalgesia." Chang G, Chen L, Mao J. Volume 91, Issue 2 (March 2007)
Member Comments