Heroin is one of the most addictive drugs in the world because of the euphoric effects it has. These are facilitated by the concoction of chemicals in heroin, including opium alkaloids like codeine, thebaine, and noscapine. Chemically, this drug is otherwise known as diacetylmorphine or diamorphine, the latter referring to medical grade heroin.
Medical grade heroin, or diamorphine, is administered as a hydrochloride salt. Its medical applications include being used as a pain reliever during childbirth or a heart attack, and it’s also commonly used in opioid replacement therapy.
This blog post will give you a deeper look at the chemicals in heroin and how they work. We’ll also talk about why heroin is so addictive, what the risks are, and what its chemical structure looks like.
In this post:
What Type of Drug is Heroin?
Heroin is classified as an opioid drug and is similar to morphine in terms of its pharmacological effects. It works by chemically binding with opioid receptors in the brain and spinal cord, which blocks pain and produces a sense of euphoria.
Heroin also binds with the intramural nerve plexuses that regulate the parasympathetic and autonomic responses of the gastrointestinal and urogenital systems. This is the main reason why addiction to heroin causes constipation and stomach pains.
Heroin is sold in the illicit drug market either as a brown powder or white powder:
- Brown powder: This is the South-West Asian variety and the most common type. It’s a form of freebased heroin and isn’t soluble in water, but is soluble in organic solvents
- White powder: This is the South-East Asian variety, which isn’t very common, and is in the form of hydrate hydrochloride salt. It’s water soluble but not soluble in organic solvents
Risks Associated With Heroin
Heroin use is associated with several health risks that are also common with other types of opioid drugs. While it mainly affects the nervous system, it also has several physical and behavioural risks.
- Breathing is either slow or irregular
- Skin is itchy and may exhibit redness
- Nausea and vomiting
- Stomach pains, mainly due to constipation
- Drowsiness and easily falling asleep
- Pupils are constricted
- Speech is incoherent or barely makes sense
- Deep sadness or depression
- Feeling of fear and apprehension
- Easily irritated
- Mood swings similar to manic-depressive swings
- Deceptive behaviour or propensity to lie
- Shyness, particularly avoiding eye contact
- Sudden loss of motivation
- Withdrawal from friends and family
- Anti-social or hostile behaviour
- Neglect of personal hygiene and appearance
- Brain damage
- Heart disease
- Liver damage
- Kidney disease
- Collapsed veins
- Pulmonary infections
- Constipation or stomach cramping
- Lung complications, including pneumonia
- Male sex dysfunction and female infertility
- Higher risk for hepatitis and HIV
- Possible fatal drug overdose
Why is Heroin Addictive?
As an opioid drug, heroin binds with opioid receptors, blocking pain signals and releasing dopamine as a result. This causes feelings of relaxation, pleasure, and happiness. The more someone takes heroin recreationally, the higher their tolerance to its effects becomes. This means that higher doses are needed in order to feel the same high as before. Eventually, heroin addiction develops.
Heroin becomes addictive when brain receptors develop tolerance to dopamine, meaning that a person will need more heroin to produce more dopamine. Greater amounts of dopamine are needed to create that feeling of pleasure that heroin, and many other drugs, are associated with.
So, a craving for the drug is developed as dopamine and tolerance levels increase. When the drug is absent, a chemical imbalance happens in the brain, causing depression and mood swings. As a result, the addicted person becomes dependent on the drug just to feel normal.
Like other drugs, heroin is addictive because it provides a shortcut to the reward system in the brain:
- Nucleus accumbens: This is the reward mediating site of the brain. When taken, heroin artificially floods the nucleus accumbens with dopamine
- Hippocampus: The hippocampus imprints memories of a rapid sense of satisfaction associated with the taking of heroin
- Amygdala: The amygdala is responsible for creating a conditioned response to the pleasurable stimuli of taking the drug
What is the Chemical Formula of Heroin?
C.R. Alder Wright was the first person to synthesise heroin from morphine in 1874. Morphine is a chemical derivative from a naturally occurring plant, opium poppy. The chemical formula and molecular structure of heroin are similar to morphine – so it’s not surprising that the pharmacological effects of the two drugs are very similar:
As you can see, both morphine and heroin contain carbon, hydrogen, nitrogen, and oxygen. Their respective proportions are also similar.
There are many chemicals in heroin, but the pharmacologically active chemicals are the opium alkaloids. Morphine is the most important alkaloid because of its anaesthetic properties. The alkaloids in opium are classified into two groups, and these make up some of the chemicals in heroin:
- Narcotics: These have analgesic and anaesthetic properties. They act upon the central nervous system and are potentially addicting. Narcotic alkaloids include:
- Relaxants: These alkaloids are non-addicting but they have relaxing effects on the involuntary smooth muscles, such as those found in the digestive system. They include:
- Noscapine (formerly called narcotine)
- Most of the other opium alkaloids
What is the Chemical Structure of Heroin?
The molecular structures of morphine and heroin are almost analogous with each other. The structure of the benzene rings, for instance, align respective to the two molecules, as shown in the illustrations below:
The simpler molecule is morphine and the more complex molecule is heroin, which, as we mentioned earlier, is a derivative of morphine. The -OCOCH3 groups that replace the -OH groups in morphine are shown in red.
By replacing the -OH group with -OCOCH3 , heroin is comparably less water soluble than morphine. However, it’s more soluble in non-polar solvents such as oils. This is the reason why the most preferred method of using heroin is by injecting it directly into the bloodstream.
Heroin is melted on tinfoil and injected into a vein using a hypodermic needle. Once in the bloodstream, it easily passes through the blood-brain barrier. Most water-soluble substances are prevented from passing through this barrier, but heroin is easily absorbed, which is also why it’s more potent than morphine in terms of pharmacological effects. However, the effect is short-lived: the acetyl groups are removed, converting it to morphine.
The short-lived, but intense pharmacological effects of heroin make it highly addictive and prone to abuse. If you know anyone who is struggling with drug abuse, it’s important to seek help immediately.
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