The discovery of antibiotics greatly improves the quality of human life but they are potentially harmful and various benefits to risk factors must be considered when ever they are used. Adverse reactions occurring with antibiotics use are usually as a result of:
The consumption of overdose of any prescribed antibiotics or medical errors.
A unique idiosyncratic effect of the compound or its metabolism.
An exaggerated response to the known pharmacology effects.
An immunology reaction to the drug or its metabolism.
Most antibiotics-related reactions are predictable and precipitate by an extension of the drug’s normal actions. Such events are dose-dependent and can be avoided by appropriate dosage adjustments.
Unpredictable reactions do occur independent of the dose and route of administration and reflect such as drug intolerance, allergy and other idiosyncratic responses. These reactions seem o preferentially affect certain body systems must commonly; blood, skin and liver.
A number of host factor (i.e. concomitant medical disorders, genetic make up and integrity of drug elimination mechanism) affect the severity and frequency of antibiotic-related adverse reactions. For example, the literature is replete with reports of coetaneous reaction occurring in HIV infected patient who have received trimethroprim sulfamethoxazole (TMP-SME) (bacterium cotrim, sptra) or amino penicillin. In addition TMP-SMZ causes non-dose-related gastrointestinal intolerance, fever and alterations in liver enzymes levels in patient with AIDS.
In addition to the drug direct influence, some reactions occur rarely and appear to be unique to the compound administered. Aplastic anemia induced by Chloramphenicol (Chloromycetin) and toxic epidermal necrolysis (Stevens - Johnson syndrome) induced by sulfonomides are typical example.