Heroin

Name:

Heroin, smack, brown, horse, diamorphine

Effects:

Rush feeling, euphoria, drowsiness, flushing of skin, analgesia, anxiolytic.  

Side effects:

dry mouth, nausea, clouded mental functioning, pupil constriction, depression of breathing, constipation, immunosuppression.  Other side effects may include abscesses, heart valve infection, pneumonia, and blood borne infections. Heroin containing starch or other contaminants may lead to deep vein thrombosis (prevalence of DVT in opioid users 13.9%)(1). 

Upon stopping using: opioid withdrawal syndrome. Typical onset within 4-24 hours after last dosage, acute symptoms (nausea, body/muscle aches, hot and cold sweats, insomnia, runny nose) may last up to weeks, post-acute symptoms (variable energy, concentration problems, disturbed sleep, anxiety) up to months. For treatment see (2). 

Mechanism of action: 

Prodrug for the systemic delivery of morphine. Heroin undergoes extensive first-pass metabolism through deacetylation. When injected this first-pass effect is avoided and heroin rapidly crosses the blood-brain barrier because of presence of acetyl-groups, rendering it way more fat-soluble than morphine itself. 

In the brain heroin is deacetylated into inactive 3-monoacetylmorphine and active 6-monoacetylmorphine (6-MAM), and then morphine, both of which binds μ-opioid receptors (MOR) and act as agonists. 

Substance and dosage:

white to brown powder, depending on additives. When injected, a typical user dose may be between 5-20mg. Experienced users may need up to several hundred mg per day. 

Overdosage: 

Loss of consciousness, slowing heart rate, (fatal) respiratory depression. 

The risk of overdosage is significantly higher when combined with other drugs. The act of injecting cocaine (stimulant) with heroin (depressant) is known as 'speedballing' and cancels out the sedating effect. The effect of cocaine wears off far more quickly than heroin however, resulting in a high risk of fatal respiratory depression.

Treatment of overdosage is done with with opioid antagonists, typically naloxone or naltrexone, countering the effects of heroin. Half-life of naloxone is shorter than that of most opioids, so that it needs to be administered multiple times until the opioid has been metabolised by the body.

(1) Deep vein thrombosis in users of opioid drugs, Br J Gen Pract 2011 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3223775/pdf/bjgp61-e781.pdf

(2) Pharmacologic treatments for opioid dependence, Kleber, MD 2007 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3202507/pdf/DialoguesClinNeurosci-9-455.pdf