Toxication is the process of metabolism

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 in which the metabolite of a compound is more toxic than the parent drug

Medication

A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

 or chemical. A parent drug or chemical that was previously non-toxic may be called a protoxin.

Toxication may involve:

• Changing the physicochemical properties to cause a change in the microenvironment


• Increasing the potency of a compound


• Conversion of the compound into:
  
  
  
  • Electrophile
  
  
  • Free radical
  
  
  • Nucleophile
  
  
  • Redox-active reactant
  
  
  
  

While toxication is generally undesirable, in certain cases it is required for the in vivo

In vivo

In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...

conversion of a prodrug

Prodrug

A prodrug is a pharmacological substance administered in an inactive form. Once administered, the prodrug is metabolised in vivo into an active metabolite, a process termed bioactivation. The rationale behind the use of a prodrug is generally for absorption, distribution, metabolism, and...

 or chemical to a metabolite with desired pharmacological or toxicological activity. Codeine

Codeine

Codeine or 3-methylmorphine is an opiate used for its analgesic, antitussive, and antidiarrheal properties...

 is an example of a prodrug, which is metabolized in the body to the opiate

Opiate

In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant.-Overview:Opiates are so named because they are constituents or derivatives of constituents found in opium, which is processed from the latex sap of the opium poppy,...

 known as morphine

Morphine

Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...

.

Examples

The breakdown of methanol

Methanol

Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

 in the mammalian liver. Methanol in itself is toxic due to its CNS depressant properties, but acquires more dangerous toxicity through its metabolites formic acid

Formic acid

Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...

 and formaldehyde

Formaldehyde

Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...

, which can cause severe acidosis

Acidosis

Acidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....

, damage to the optic nerve

Optic nerve

The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...

, and other life-threatening complications.

The metabolism of paracetamol

Paracetamol

Paracetamol INN , or acetaminophen USAN , is a widely used over-the-counter analgesic and antipyretic . It is commonly used for the relief of headaches and other minor aches and pains and is a major ingredient in numerous cold and flu remedies...

 (acetaminophen) to the hepatotoxic

Hepatotoxicity

Hepatotoxicity implies chemical-driven liver damage.The liver plays a central role in transforming and clearing chemicals and is susceptible to the toxicity from these agents. Certain medicinal agents, when taken in overdoses and sometimes even when introduced within therapeutic ranges, may injure...

 metabolite NAPQI

NAPQI

NAPQI is a toxic byproduct produced during the xenobiotic metabolism of the analgesic paracetamol...

 via the cytochrome P450 oxidase

Cytochrome P450 oxidase

The cytochrome P450 superfamily is a large and diverse group of enzymes. The function of most CYP enzymes is to catalyze the oxidation of organic substances. The substrates of CYP enzymes include metabolic intermediates such as lipids and steroidal hormones, as well as xenobiotic substances...

 system.

Metabolic Activation of N-Hydroxy-2-aminofluorene and N-Hydroxy-2-acetylaminofluorene by Monomorphic N-Acetyltransferase (NAT1) and Polymorphic N-Acetyltransferase (NAT2)
Role of cytochrome P4501B1 in benzo[a]pyrene bio-activation to DNA-binding metabolites
Evidence from 32p-postlabeling for formation of 3-hydroxybenzo[a]pyrene and benzo[a]pyrene-3,6-quinone as major proximate genotoxic intermediates