<unk>  leading to hepatitis (drug-induced hepatitis) with granulomata. Other causes were excluded with extensive investigations. Liver biopsy. H&E stain. As research better explains the biochemistry of drug use, fewer<unk> s are Type B and more are Type A. Common mechanisms are: * Abnormal pharmacokinetics due to * genetic factors * comorbid disease states * Synergistic effects between either * a drug and a disease * two drugs *Antagonism effects between either *a drug and a disease * two drugs Abnormal pharmacokinetics Comorbid disease states Various diseases, especially those that cause renal or hepatic insufficiency, may alter drug metabolism. Resources are available that report changes in a drug's metabolism due to disease states. The Medication Appropriateness Tool for Comorbid Health Conditions in Dementia (MATCH-D) criteria warns that people with dementia are more likely to experience<unk>  effects, and that they are less likely to be able to reliably report symptoms. Genetic factors Abnormal drug metabolism may be due to inherited factors of either Phase I oxidation or Phase II conjugation. Pharmacogenomics is the study of the inherited basis for abnormal drug reactions. Phase I reactions Inheriting abnormal alleles of cytochrome P450 can alter drug metabolism. Tables are available to check for drug interactions due to P450 interactions. Inheriting abnormal butyrylcholinesterase (pseudocholinesterase) may affect metabolism of drugs such as succinylcholine Phase II reactions Inheriting abnormal N-acetyltransferase which conjugated some drugs to facilitate excretion may affect the metabolism of drugs such as isoniazid, hydralazine, and procainamide. Inheriting abnormal thiopurine S-methyltransferase may affect the metabolism of the thiopurine drugs mercaptopurine and azathioprine. Interactions with other drugs The risk of drug interactions is increased with polypharmacy. Protein binding These interactions are usually transient and mild until a new steady state is achieved. These are mainly for drugs without much first-pass liver metabolism. The principal plasma proteins for drug binding are: # albumin # α1-acid glycoprotein # lipoproteins Some drug interactions with warfarin are due to changes in protein binding. Cytochrome P450 Patients have abnormal metabolism by cytochrome P450 due to either inheriting abnormal alleles or due to drug interactions. Tables are available to check for drug interactions due to P450 interactions. Synergistic effects An example of synergism is two drugs that both prolong the QT interval.
Adverse drug reaction
Bullous drug reaction
Anticonvulsant hypersensitivity syndrome
Idiosyncratic drug reaction
Drug interaction
Foreign body reaction
Drug intolerance
Paraneoplastic syndrome