Introduction
Drug sensitivity or drug intolerance are conditions where a person can not tolerate the side effects caused by the medication, usually at the therapeutic or sub-therapeutic dosages. Some drug intolerance is caused due to genetic variation in drug metabolism (breakdown of drugs through living organisms, usually the enzymes).
What Is a Drug Hypersensitivity Reaction?
Drug hypersensitivity reactions include allergic, pharmacological, and pseudoallergic reactions to certain medications that are caused due to immunological or inflammatory responses. Drug treatment usually leads to adverse reactions known as ‘side effects’ caused due to the inherent biological effects of the drug. There are two types of reactions,
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Pharmacologically mediated adverse drug reaction (ADR) - Type A.
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Hypersensitivity reactions - Type B.
What Is an Adverse Effect of Drugs?
Adverse effects are the side effects that are unwanted and undesirable effects associated with the drug. These effects can vary from a simple runny nose to some severe effects such as heart attack or liver damage.
The Adverse Drug Reaction May Be Divided Into Two Types
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Type A:
It is also called the Pharmacologically mediated adverse drug reaction, making up to 85 to 90 percent of all drug reactions. Under sufficient dosage and exposure, it can affect any person and is caused by the known pharmacological properties of a drug. For example, Type A reaction causes diarrhea in response to antibiotics and gastritis due to long-term intake of NSAIDs (non-steroidal anti-inflammatory drugs) or aminoglycoside nephrotoxicity (quick deterioration of the kidney functions due to toxic effects of the drugs).
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Type B:
Type B reaction is the hypersensitivity reaction which makes up 10 to 15 percent of the adverse drug reaction. It affects a susceptible group of patients, and the signs and symptoms differ from the pharmacological actions of the drug. Immunological or inflammatory mechanisms mediate all adverse effects caused by Type B reactions. However, these are not involved in immunological or inflammatory cells, known as idiosyncratic sensitivity and exaggerated reactions.
What Is the Classification of Hypersensitivity Reaction?
The main role of the immune system is to maintain health and protect the body against microbial invasion. Hypersensitivity reactions are adverse effects that can be caused due to exaggerated immune or inflammatory responses. There are four types of hypersensitivity reactions; these are:
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Type I Hypersensitivity:
Type I hypersensitivity is an immediate reaction that includes immunoglobulin E (IgE). These IgE mediate the release of antibodies against the soluble antigens, which results in the degranulation of mast cells (a type of white blood cells seen in the connective tissue), and the release of histamines (a chemical found in some body cells) and other inflammatory mediators.
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Type II Hypersensitivity:
Type II hypersensitivity is a cytotoxic reaction that engages IgM and IgG antibodies, activating the complement system and cell damage.
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Type III Hypersensitivity:
Type III is a complex immune reaction that involves IgG, IgM, and sometimes IgA antibodies. The activation of the complement system is due to the build-up of these immune complexes, which result in polymorphonuclear leukocytes (immune cells released during allergic reactions, infection, etc.) and cause tissue damage.
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Type IV Hypersensitivity:
Type IV reaction is delayed and includes T-cell-mediated reactions. T-cells, also known as macrophages, are activated by releasing cytokines (small proteins) and causing tissue damage.
What Are the Common Hypersensitivity Reactions of Drugs?
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Tinnitus After a Normal Aspirin Dosage:
Many people are allergic to Aspirin, and some have non-allergic sensitivity (when taking the drug, the person will have symptoms but no allergy). Aspirin is usually taken to deal with pain or as a part of the heart regime. Aspirin is a group of Salicylates that may cause tinnitus when consumed in large amounts. Salicylates are ototoxic, leading to hearing loss and tinnitus on overdosage. However, the effects of aspirin on tinnitus are temporary and can be reversed. Therefore, it does not require a complete stoppage of Aspirin.
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Respiratory Disease Caused Due to Aspirin Exacerbation:
Aspirin exacerbated respiratory disease (AERD) includes asthma, nasal polyps, and sensitivity to aspirin and NSAIDs. Signs and symptoms may include difficulty breathing, wheezing, coughing, sneezing, and running nose; these occur suddenly and can be serious. Therefore, other NSAIDs and Aspirin should be avoided.
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Liver Failure After a Normal Dosage of Acetaminophen:
Acetaminophen is a non-prescribed analgesic and antipyretic drug to deal with mild pain and fever. It is harmless at low dosages and has hepatotoxic potential (acute or chronic liver injury) when overdosed resulting in acute liver injury or death due to acute liver failure. Therefore, long-term use and overdose of Acetaminophen should be avoided.
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The Fatal Poisoning of the Newborn by Codeine Through Breastfeeding:
Breastfeeding should be avoided when the mother is under treatment with Codeine. It may result in severe adverse effects such as excessive sleepiness and difficulty in breastfeeding and breathing, which may be fatal. Codeine is an opioid used to treat pain and also reduce coughing. When Codeine enters the body, it is changed into its active form, morphine, in the liver. A huge amount of morphine in breast milk causes these adverse effects.
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Muscle Pain Due to Statin Therapy:
Mild muscle pain and tiredness are common side effects of Statin. Long-term use of Statin to reduce cholesterol leads to severe muscle pain. It is characterized by soreness, tiredness, and mild to severe muscle pain. Usually, the muscle pain is relieved two to three weeks after stopping the statin intake.
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Antibiotic Adverse Effects:
The non-selective destruction of the targeted bacteria usually causes adverse antibiotic effects. Common adverse effects are nausea, voting, diarrhea, rashes, and gastrointestinal distress. For example, Penicillin is a common antibiotic that causes adverse effects such as hives, rashes, and itching and sometimes can even cause life-threatening conditions. In addition, about 10 percent of people are allergic to the widely used Penicillin.
What Is Multiple Drug Intolerance Syndrome?
Multiple drug intolerance syndrome refers to having more than three unrelated drug intolerance. About two to five percent of the population may have multiple drug intolerance syndrome. This syndrome usually occurs as age increases as there is an increase in the number of lifetime drug exposure. It is usually seen in females and those being treated for many different health conditions. The adverse effects can be caused by all the medications the patients take, which cause rashes, gastrointestinal problems, headaches, coughing, muscle aches, and fever. Multiple drug syndrome can be treated by avoiding medications and careful rechallenge when required.
Conclusion
Drug sensitivity or drug intolerance is a condition caused by the inability to overcome the adverse effects of drugs. Some adverse effects include rashes, headache, nausea, vomiting, gastrointestinal distress, fever, and difficulty breathing, and they may even cause fatal effects. Drug intolerance can be managed by avoiding the specific drug to which a person is allergic and by taking the proper dosage prescribed by the doctors to avoid overdose.
