Time Factors in Adverse Drug Reactions

I) The total exposure to a drug during the lifetime of the patient or an important period of life (i. e., the quantity of the drug administered). This factor may be of influence on reproduction, foetal development, teratogenicity, oncogenicity, etc. and also on a disease such as analgesic-interstitial nephritis. 

III) Single applications of a drug, either as part of a treatment period or as a sporadic single dose, often used for symptomatic therapy of a discomfort, or minor disease. 

Intermittent exposures have also been used with rifampicin (with 1-3 single exposures a week) and seemed to enhance markedly the otherwise extremely rare appearance of an acute thrombocytopenia. If exposure is sporadic, valuable epidemiological studies cannot usually be realised. 

This is the time between the last drug exposure and the appearance of the first symptoms, if the mechanism is considered to be allergic (Mayer 1933). Frequently there is a definite relationship between the reaction time and the type of clinical symptoms. This relationship was described by von Pirquet and Schick as early as 1905 with respect to anaphylactic shock and serum sickness due to foreign sera. 

Serumsid ness/allergic angiitis/ Arthus reaction 

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