Opioid dependence

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Opioid dependence

Psychological disorders

Bipolar and related disorders

Bipolar disorder

Feeding and eating disorders

Anorexia nervosa

Bulimia nervosa

Medication-induced movement disorders and other adverse effects of medication

Neuroleptic malignant syndrome

Serotonin syndrome

Somatic symptom and related disorders

Factitious disorder

Somatic symptom disorder

Trauma and stressor-related disorders; Abuse

Physical and sexual abuse

Post-traumatic stress disorder


Opioid dependence


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USMLE® Step 1 questions

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High Yield Notes

11 pages


Opioid dependence

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USMLE® Step 1 style questions USMLE

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A 2-day-old female neonate is examined in the newborn nursery to evaluate poor feeding. The infant was born vaginally to a 28-year-old woman who did not receive consistent prenatal care during her pregnancy. The pregnancy was complicated by intrauterine growth restriction. The infant was breastfed normally until two hours ago when she became tachypneic and restless. Temperature is 37.8°C (100°F), pulse is 170/min, respirations are 85/min, and blood pressure is 60/35 mmHg. Physical examination shows increased tone in all extremities. The patient appears diaphoretic and has a high-pitched cry and occasional sneezes. There are no dysmorphic facial features. Which of the following best describes the underlying etiology of this infant’s presentation?  


Worldwide, opioids are the most common cause of drug related deaths.

The number of individuals who use them has quadrupled in the last 20 years, with an uptick in heroin use, an even bigger uptick in prescription opioid use, and a large number of people using both.

Because of their potential for addiction and overdose, opioids are regulated substances in many countries.

As a class, opioids share one thing in common—they bind to opioid receptors in the brain, spinal cord, and gastrointestinal tract.

Some are endogenous, meaning that they are produced naturally by the body, like endorphin, short for endogenous morphine.

But others are exogenous, meaning that they come from the environment, like heroin and morphine, which come from the opium poppy—a flowering plant that oozes a milky white liquid—while others like fentanyl are synthesized in the laboratory.

To understand how opioids work, let’s zoom into a region of the brain tissue that has opioid receptors.

Normally, in the absence of endorphins, inhibitory neurons secrete a neurotransmitter that prevents nearby neurons from releasing the neurotransmitter dopamine.

Now, let’s say someone goes to play a rigorous game of badminton.

Exercise releases endorphins which activate the three major opioid receptors located on the inhibitory neurons, called the mu, kappa, and delta receptors.

As endorphins bind to these receptors, they block the inhibitory neuron from releasing neurotransmitters, allowing the dopamine secreting neurons to freely unload dopamine.

The dopamine then gets picked up by a third neuron in the same area.

When dopamine release takes place in pain processing regions of the brain like the thalamus, brainstem, and spinal cord, the result is feeling less pain.


Opioid dependence is a medical condition characterized by compulsive use of opioids despite knowing the underlying danger, and developing withdrawal syndrome when opioid use stops. Opioids include drugs like morphine, heroin, codeine, oxycodone, hydrocodone, etc. The treatment for opioid dependence involves a combination of therapy and medications, with support from family and friends.


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  2. "Harrison's Principles of Internal Medicine" McGraw Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Pharmacological therapies for management of opium withdrawal" Cochrane Database of Systematic Reviews (2018)
  5. "An examination of psychiatric comorbidities as a function of gender and substance type within an inpatient substance use treatment program" Drug and Alcohol Dependence (2011)
  6. "Cellular basis of memory for addiction" Dialogues in Clinical Neuroscience (2013)

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