AN OVERVIEW ON PHARMACOVIGILANCE

Pharma Admission

igmpi

pharma admission

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3. Objectives
The mission of Pharmacovigilance is  to contribute to the protection of public  health in the regulation of the safety, quality and efficacy of medicines for human use and to ensure the healthcare professionals and patients have assess to information about the safe and effective use of medicine25.

Our current ADR reporting system involves a passive approach in which providers are encouraged to report adverse events via e-mail, telephone, or paper. In addition, practitioners may report ADRs directly to a hospital pharmacist who is present in the hospital.

Primary objectives

  • Raise awareness on the magnitude of drug safety problems and increase the rational and safe use of drugs.
  • Identification of potential safety hazards, evaluation, monitoring and where appropriate, implementation of regulatory action to maximize benefit and minimize risks associated with medicinal products.
  • Early detection of unknown adverse drug reaction and increase in frequency of known adverse drug reactions
  • To compare the number of ADRs identified by  this traditional passive method
  • To determine the significance of ADRs those were reported by patients but unknown to their provider.
  • Convince healthcare professionals that reporting to ADR is their professional and moral obligation.
  • Identification of risk factors and possible mechanism underline adverse reactions

Secondary objectives

  • Aid health professionals in becoming vigilant in the detection and reporting of ADRs and other drug induced problems.
  • Anticipate the various combinations by which  ADRs can be caused
  • Considering drug-drug interactions and drug-food interactions which may  responsible for ADRs

4. Functions of Pharmacovigilance
From early development through post-marketing, we need to master safety information to make critical decisions — and that requires more coordination than traditional safety systems provide. The best approach is one that integrates safety across both time and function. This lifecycle approach keeps precisely informed about product’s safety profile as it evolves — so we can not only meet regulatory and pharmacovigilance requirements, but also achieve our commercial goals2, 26


Fig.1: Different functions of Pharmacovigilance

With Quintiles, we’ll have one point of contact and access to a global array of safety and risk management professionals to help us:

  • Monitor safety and manage case reports
  • Mitigate risk earlier in development
  • Manage and maximize your product's risk-benefit profile 
  • Improve the market value of your product with proactive planning and robust risk management.

5. Adverse Drug Reactions
The World Health Organization (WHO) defines an adverse drug reaction (ADR) as “Any response to a drug which is noxious and unintended, and which occurs at doses normally used in man for prophylaxis, diagnosis or therapy of disease or for modification of the physiological function”. This definition excludes overdose (either accidental or intentional), drug abuse, and treatment failure and drug administration errors. The terms “Adverse Drug Reaction” and “Adverse Drug Event” are not synonymous27.

Adverse Event
The WHO definition of an adverse event is “Any untoward medical occurrence that may present during treatment with a pharmaceutical product but which does not necessarily have a causal relationship with this treatment”. As soon as someone suspects a casual relationship between the untoward occurrence and an administered medicine, the event is turn into a suspected adverse drug reaction.


Fig.2: Adverse drug reactions flow chart

Side Effect
Any unintended effect of a pharmaceutical product occurring at doses normally used in humans, which is related to the pharmacological properties of the drug.

Unexpected adverse Reaction
An ‘Unexpected Adverse Reaction’ means an adverse reaction, the nature, severity or outcome of which is not consistent with the Summary of Product Characteristics.

Serious Adverse Reaction
A ‘Serious Adverse Reaction’ means an adverse reaction which results in death, is life threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability or incapacity or is a congenital anomaly/birth defect.

Abuse of Medicinal Products
Abuse of medicinal products’ means the persistent or sporadic, intentional excessive use of medicinal products which is accompanied by harmful physical or psychological effects.

Classification
Traditionally, ADRs are classified into two categories

  • Type A
  • Type B

Type A ADRs
Type A (Augmented) reactions are usually the exacerbation of pharmacological effects of a drug and thus are dose dependent. An example is insulin induced hypoglycemia. These reactions are usually predictable due to the known pharmacology of a drug and thus preventable. The incident of occurrence of type A reactions is high in any society; they are responsible for considerable morbidity. The morbidity rate is relatively low since most type A reactions will disappear by reduction of the dose or by discontinuation of drug.

Type B ADRs
Type B (Bizarre) reactions are hypersensitivity reactions and are not dose dependent. An example of penicillin induced hypersensitivity reaction. These reactions are often not predictable and preventable (unless the patient has a known history of this type of reaction). This type of reaction is rare but often serious with a high mortality rate.

The basic difference between Type A ADRs and Type B ADRs describes

Recently different newer classifications have been proposed. One of these classifications include

Type A (augmented)                        Type B (Bizarre)

Type C (Continuous)                        Type D (Delayed effect)

Type E (Rebound effect)                   Type F (Failure of therapy)

Wills and Brown have proposed another classification on the basis of mechanism into eight new categories which includes

Type A (augmented)                         Type B (Bizarre)

Type C (Chemical)                            Type D (Delivery)

Type E (Exit)                                   Type F (Familial)

Type G (Genotoxicity)  Type H (Hypersensitivity)  Type U (Unclassified)

Table.1: Differentiation between type ADRs and type B ADRS

S. No.

Type A ADRs

Type B ADRs

1.

These type of reactions are dose dependents.

There is no simple relationship with the dose of the drugs.

2.

They are predictable to known pharmacology.

They are not predictable.

3.

Genetic factors may be important in case of these reactions.

These reactions are dependent on host factors

4.

These reactions are very common in frequency.

These reactions are uncommon in frequency.

5.

They are variable but usually mild.

They are also variable but more severe than type A reactions.

6.

They show high morbidity.

They also show high morbidity.

7.

They possess low mortality.

They posses high mortality.

8.

They calculated as 80% overall proportion of ADRs.

They calculated as 20% of overall ADRS.

9.

These reactions are first detected in phase I & III of clinical trials.

These reactions are detected in Phase IV and occasionally in phase III.

10.

These reactions are usually because of parent drug or stable metabolite.

These reactions may be because of parent drug or stable metabolites.

Factors which predisposing ADRs
There are many factors that can predispose to the occurrence of adverse drug reactions in a patient. Patients who have one or more following predisposing factors are at high risk of developing ADRs.

*  Polypharmacy

*  Multiple and intercurrent disease

*  Age

*  Drug characteristics

*  Gender

*  Race and genetics

Polypharmacy
Patients with multiple drug therapy are more prone to develop as adverse drug reaction either due to alteration of drug effect through an interaction mechanism or by synergistic effect. The amount of risk associated with multiple drug therapy increases in direct proportion to the number of drug administered4.

Multiple and intercurrent disease
Patient with multiple diseases are at an increased risk of developing an ADR due to multiple drug used for their multiple diseases. Similarly, patients with impaired hepatic or renal status are also at a high risk of developing an ADR to drugs which are eliminated by these organs. For example a patient with decreased renal function who is treated with amino glycosides is at an increased risk of developing nephrotoxicity unless appropriate dosage adjustment is made6,9.

Age
Elderly and pediatric patients are more vulnerable to develop ADRs. Elderly patients are more susceptible to ADRs due to the physiological changes (pharmacokinetics and pharmacodynamic) which accompany aging, and also because they are often taking many drugs for chronic and multiple diseases. Nitrates or angiotensin converting enzyme inhibitor induced postural hypotension in an elderly patient is an example of this kind, where the reaction may be exacerbated by age related impaired baroreceptor responses to a change in posture. Pediatric patient may develop serious adverse drug reactions to some drugs since all children, especially neonates, differ in their drug handling capacity compared to adults. An example of such a serious reaction is the Gray Baby Syndrome with chloramphenicol.

Drug characteristics
Some drugs are highly toxic in nature and patients who are treated with these drugs are at an increased risk of ADRs. For examples, nausea and vomiting is a common adverse drug reaction seen in patients treated with anticancer drugs. Also, patients who are treated with drugs which have narrow therapeutic index such as digoxin and gentamicin are more susceptible to develop ADRs, as a slight increase in the serum drug concentration of these drugs may result in drug toxicity.

Gender
It has been reported that women are more susceptible to develop ADRs, for unknown reasons. Chloramphenicol induced aplastic anemia and phenylbutazone induced agranulocytosis in twice and trice as common, respectively in women patients.

Race and genetics
It is evident that ADRs are more common in genetically predisposed individual. For example, patients who are genetically deficient of Glucose-6-Phosphate Dehydrogenase (G6PD) enzyme are at higher risk of developing hemolysis due to primaquine than those who are not, race and genetic polymorphism may account for alterations in handling of drugs and their end organ effects.

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