What Chemicals Are In Drugs?

Lucy Bell-Young

by Lucy Bell-Young

17th March 2021

Chemicals in drugs are everywhere. From medicines and vitamins to alcohol and coffee, drugs come in a lot of different disguises. Their uses range from medical treatments to recreational activities, but whatever they’re used for, their definition stays the same: drugs are substances that, when ingested or administered, have physiological effects on the body.

Illicit drugs notoriously contain harmful chemicals, but this isn’t the case with every drug we encounter on a day-to-day basis: some chemicals are necessary. The chemical composition of even the most common drugs is important in understanding the pharmacological aspects of drugs for various applications. 

Continue reading to discover more about two noteworthy types of drug precursors, what drug degradation is, and the chemistry behind three of the most illicit drugs on the market. 

Tablets and pills on the table

What Chemicals Can Be Found In Drugs?

All drugs are chemicals, but not all chemicals are drugs. Drugs have chemical structures that are familiar to us, which is why some can have a range of pharmacological effects, such as medicines used to treat illnesses. 

But drugs are wide-ranging, with each one affecting the body in different ways. For example, the chemistry behind coffee tells us that caffeine works by attaching itself to the adenosine receptors in your brain. This prevents the receptors from detecting adenosine, an inhibitory neurotransmitter that promotes sleep, thus making you feel less tired and more alert. As you can see, the chemistry behind drugs is very refined and even a miniscule dosage can have profound effects on the human body.

Just like food, drugs are composed of ingredients known as chemical components. These can be mainly categorised into two key players: 

  • Inactive ingredients: Also known as excipients, these have no direct pharmacological role in the body
  • Active pharmaceutical ingredients: Also known as APIs, these have notable effects on the person who takes the drug

These ingredients are generally combined together to make a drug’s known chemical structure more reproducible and stable. For this reason, various chemical ingredients in drugs, whether active or inactive, must comply with strict regulations when being traded in global markets because they can become drug precursors to illegal drug products.

What Are Drug Precursors?

Also known as precursor chemicals, drug precursors are primarily legitimate substances with diverse applications. They can be utilised to manufacture both legal and illegal drugs. These chemicals can either become ingredients of products, or be extracted from manufactured drugs and used illicitly.

Misusing or illegally using these substances is called drug precursor diversion. Some common examples of where these precursors are misused as ingredients are cocaine, methamphetamine, heroin, etc. 

Here are two noteworthy drug precursors that can be illegally diverted from their supposed primary legitimate use:

  1. Ephedrine and pseudoephedrine

Mainly used as ingredients for medical drugs against influenza, nasal congestion, and allergies, these drug precursors can also be chemically reprocessed to produce methamphetamine. A kilo and a half of ephedrine-based products can be used to produce a kilogram of meth when reprocessed.

  1. Acetic anhydride (AA)

Mainly used for the industrial production of textiles, cigarette filters, perfumes, plastics, explosives, and photochemical agents, AA can also be used to make heroin – 1.5 litres of AA can be chemically reprocessed to produce one kilogram of heroin, which is among the most addictive illegal substances in the world. 

These are just two prime examples of drug precursors being diverted from their main legitimate intended purposes. This is why these precursors are strictly regulated during trade with proper storage practices. Storage compliance doesn’t just secure them from illegitimate diversion, but also prevents their fast degradation.

Structural chemical formula of caffeine molecule with roasted coffee beans
Caffeine is a chemical found in coffee that affects your brain chemistry

What Is Drug Degradation?

As these ingredients have varied medical applications, it’s crucial to uphold their stability. This is because, in drugs, the stability of the contained ingredients can’t be maintained for very long due to various factors. The loss of a drug’s stability is called drug degradation.

Drug degradation happens when the preformulated chemicals in a drug break down, which may affect their efficacy, quality, and safety. However, drugs naturally break down on their own over time, even with proper storage conditions. This is why they have estimated expiry dates, and also why you shouldn’t take drugs that have passed their expiry date. 

There are several factors that can make the natural degradation of drugs much faster, such as exposure to oxidizing materials, acids, alkalis, moisture, light, change in temperature, and so on. 

Degradation is akin to food spoilage: just as expired food can make you ill, so can expired drugs have unwanted and sometimes dangerous health implications. This is because drug degradation affects the chemical structure of a drug and, in turn, alters its effects on the human body. This scientific principle is applicable to all drugs, whether legally or illegally manufactured.

Examples Of Chemical Drugs

  1. Cocaine

Cocaine is an addictive stimulant drug created from South America’s native coca plant leaves. Despite having valid medical purposes, such as anesthesia in surgery, cocaine is an illegal substance when used recreationally. Street versions of cocaine are often mixed with cornstarch and other common powder substances for concealment and profit purposes. 

This is the most consumed and abused illicit drug in the world, causing many serious health effects. In a nutshell, cocaine produces its effects by blocking the reuptake of feel-good neurotransmitters and hormones, such as dopamine and serotonin. This facilitates a short-lived, but intense rush of euphoria. 

Blackboard with the chemical formula of Cocaine
The chemicals in cocaine block the reuptake of dopamine and serotonin, creating a short euphoria
  1. Methamphetamine

Popularly known as crystal meth, methamphetamine is a highly addictive stimulant that affects the central nervous system. Usually found in crystalline powder form, methamphetamine has a bitter taste, white colour, no odour, and will dissolve in water or alcohol-based solutions. 

It was previously utilised to treat nasal congestion and even bronchial ailments in the early 1900s. However, it eventually became illegal in most countries as more researchers demonstrated its long-term negative impact on health despite its pleasurable addictive component. Methamphetamine was initially developed from amphetamine. However, meth can also be chemically derived, extracted, or produced from other drugs, such as the ephedrine-based compounds we mentioned earlier.

  1. Heroin

One of the most widely-abused drugs is an opiate called heroin. This is an illicit drug derived from another drug, morphine, which is naturally produced using seed pods from the opium poppy plant. In powder form, heroin can be white or brown. In other cases, it may appear as black tar heroin. 

Originally utilised as a pain reliever, much like other opioid substances, heroin is an illicit drug in many countries and is very dangerous to consume. Meanwhile, its parent substance, morphine, is legal in medical use, though it’s highly regulated. As we touched on earlier, heroin can be derived from other chemicals or drug precursors, such as acetic anhydride.


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