PHARMACOVIGILANCE AND DRUG SAFETY

 


What is Pharmacovigilance?

Pharmacon (Greek) =Medical substances

Vigilia (Latin) = To keep watch

It is also known as “Drug safety”.

WHO definition:

It is the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug-related problems.

Recently its concerns have been widened to include herbs, traditional and complementary medicines, blood products, biological medical devices and vaccines.

Aims of pharmacovigilance:

To improve patient care and safety in relation to the use of medicines, and all medical and paramedical interventions.

To improve public health and safety in relation to the use of medicines.

To contribute to the assessment of benefit, harm, effectiveness and risk of medicines, encouraging their safe, rational  and more effective use.

To promote understanding, education and clinical training in pharmacovigilance and its effective communication to health professionals and the public.

Some basic definitions

Adverse event :

Any untoward medical occurrence that may present during treatment with a pharmaceutical product but which does not necessarily have a casual relationship with this treatment.

Adverse drug reaction:

A response which is noxious and unintended, and which occurs at doses normally used in humans for the prophylaxis, diagnosis, or therapy of disease, or for the modification of physiological function.

Serious adverse event or reaction:

A serious adverse event or reaction is any untoward medical occurrence that at any dose:

  • Results in death

  • Requires inpatient hospitalization or prolongation of existing hospitalization

  • Result in persistent or significant disability/incapacity

  • Is life-threatening 

Unexpected adverse reaction:

An adverse reaction, the nature or severity of which is not consistent with domestic labelling or market authorization, or expected from characteristics of the drug.

Suspected unexpected serious adverse reaction:

A serious adverse event becomes a SUSAR if the serious event is suspected (possibly, probably or definitely) to be the investigational medicinal product and is unexpected i.e not previously documented in any information on protocol.

Causality assessment:

The evaluation of the likelihood that a medicine was the causative agent of an observed adverse reaction. Causality assessment is usually made according established algorithms

Dechallenge:

The withdrawl of a drug from a patient; the point at which the continuity, reduction or disappearance of adverse effects may be observed.

Rechallege:

The point at which a drug is again given to a patient after its previous withdrawl.


Types of ADR:

TYPE

CHARACTERISTIC

EXAMPLE

Type-A

(Augmented)

Predicted from the known pharmacology of the drug.These reactions are dose dependent.

Bleeding with anticoagulants.

Type-B

(Bizzare)

These are not predicted from the known pharmacology of the drug. They are relatively dose independent.

Apirin induced asthma

Type-C

(Chronic)

Which are related to chemical structure and its metabolism.

Paracetamol hepatotoxicity

Type-D

(Delayed)


Which appears after many years of treatment.

Bladder carcinoma after treatment with cyclophosphamide

Type-E

(End of treatment)

Occur after drug withdrawl 

Seizures after stopping phenytoin

Type-F

(Failure of therapy)

May be caused by caused by a drug interaction


CYP450 enzyme interaction


Who should report adverse drug reaction ?

All health care workers, including doctors, dentists, pharmacists,

nurses and other health professionals are requested to report all suspected adverse reactions to drugs (including vaccines, x-ray contrast media, traditional and herbal remedies), especially when the reaction is unusual, potentially serious or clinically significant.

What to report ?

For new drugs 

  • All suspected reactions including minor ones

For established drugs 

  • All serious or unexpected ADRs

  • Any increased frequency of a given reaction

  • All suspected ADRs associated with drug-drug interactions

  • ADRs of special population (elderly, child, pregnancy and lactation)

  • ADRs associated with drug abuse and drug withdrawls

  • ADRs occurring from overdose or medication error 

  • Lack of efficacy

Conclusion

  • If all the health care professionals including physicians, nurses, pharmacist and others including the patient report all ADRs then regulatory authority can take action as soon as possible, and drugs which are banned worldwide may be not available in India too.

  • Careful premarketing screening should reduce the problem but may also reduce the number of potentially useful drugs available for full development and subsequent licensing.

  • Better risk management strategies are needed to handle problems when they arise, by means other than revocation of licenses.


References
https://vial.com/blog/articles/what-is-pharmacovigilance/
https://www.jli.edu.in/blog/basics-of-pharmacovigilance-a-quick-overview/

Written by: B. Satya Priya

Pharm. D

ClinoSol ID: 179/1022

 





                                                                 




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