INTRODUCTION occurs when two or more drugs are

INTRODUCTION

Geriatrics
are different from adolescents with respect to high susceptibility to undesired
effects, comorbidity, polypharmacy and the rate of absorption, distribution,
metabolism and excretion of drugs. (Guideline on Special Populations; 1993).
The pharmacodynamics and pharmacokinetics of drugs in the geriatrics are
changed as a result of their advanced age and some physiological alterations
that occur in the body influence how drugs are managed. This alteration can
raise the possibility of drug toxicity and untoward drug reaction.( Mangoni A
et al; 2004 Marzolini C  et al; 2011 Mallet
L et al; 2007).

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Drug-
drug interaction is a reaction than occurs when two or more drugs are
concurrently used. (Council on FamilyHealth; 2004) Drug-drug interaction can
produce a harmful effect in terms of reducing the therapeutic effect of a drug,
increasing adverse drug reaction or impair therapeutic outcome; or it can
produce a useful effect. Old age, concurrent use of multiple medication and
several prescribers are some of the factors that expose one to potential drug
interaction (Bjerrum L et al; 2008) Due to several medications used by the
elderly and their distorted pharmacokinetics, they will probably experience
drug-drug interaction(Marzolini C et al; 2011 Delafuente C et al; 2003)

Adverse
drug reaction and hospital admission are as a result of drug interactions. Drug-drug
interaction accounted for about 4.5 to 6.5% adverse drug reaction (Obreli-Neto
PR et al; 2012 Buc?a C et al; 2013), 1.1% hospital admission and 0.1% hospital
visits (Dechanont S et al; 2014) in the elderly. The aim of this study was to
examine the prevalence of potential drug interactions in the prescriptions of
geriatric patients in Nnamdi Azikiwe University Teaching Hospital, Nnewi.

METHODS

STUDY POPULATION AND
STUDY DESIGN

The study is a retrospective cross
sectional survey of patients > 65 years old, who had a length of stay
greater than 48 hours in the adult female or male ward of Nnamdi Azikiwe
University Teaching Hospital(NAUTH) Nnewi and had more than two medicines in
their prescriptions between June 2016 to June 2017. NAUTH is one of the leading
teaching hospitals in Nigeria and it is designated as centre of
excellence in nephrology. It provides general outpatient
and inpatient services in the specialty units available. It has over five
outstations located in rural areas for providing community medicine services to
the adjoining rural communities.

Medical
records of the patients were collected using random sampling technique and 400
prescriptions that met the requirements were used for the study.

RESEARCH
INSTRUMENT AND VALIDATION

The demographic details of the patients, drug use
and administration were taken from their case files and converted into a data
collection form. The data collection form was pre- tested using records of ten
patients from the Adult Male ward and necessary adjustments made before the
commencement of the study. Drug Drug interaction was assessed
using Lexi Comp drug interact android
mobile application trial version. It classifies the DDI
based on its severity, risk and reliability. The severity in the documentation
of DDI was categorized as major, moderate and minor; the risk rating used is as
follows: no known interaction, no action needed, monitor therapy, therapy
modification, avoid combination; while the reliability was categorized as
excellent, good, fair and poor. 

DATA
ANALYSIS  

The
data obtained was analyzed using Statistical Package
for Social Sciences (SPSS) version 17

ETHICAL
CONSIDERATION

Full
ethical approval with document number, NAUTH/CS/66/VOL9/108 was gotten from the
Ethical Review Board of Nnamdi Azikiwe University Teaching Hospital , Nnewi.

RESULTS

The
mean age of the patients was 69 (±10) years with less than half being male
(46%). From the patients studied, higher number were admitted for hypertension
(36.75%), followed by malaria and diabetes (18%), then Ulcer (7.75%), Arthritis (7%), Benign Prostatic
Hyperplasia (5.5%), Atherosclerosis (4%), and others (3%). In relation to
patient outcomes, 17 % (68) of participants were recorded dead, while, 83%
(332) were still alive. A total of 1924 drugs were prescribed, with each
patient having an average of 4.81 (± 1.32) drugs. The prevalence of DDI was
59.75% as a total of 239 prescriptions out of 400 had drugs with the potential
to interact, while a total of 161 prescriptions did not contain drugs that
could potentially interact. A total of 816 potential drug-drug interactions (pDDIs)
were established during the study period with an occurrence rate of 2.04 DDIs
per patient. Major DDIs accounted for 47 (5.7%) of the DDI (at 0.12 major DDI
per patient), moderate DDIs accounted for 591 (72.4%) of the DDIs (at 1.48
moderate DDIs per patient), while minor interactions accounted for 178 (21.8%)
of the DDIs (at 0.45 minor DDIs per patient).

The different Drug – Drug Interactions suggested by
the lexi comp Drug interact, in order of severity and risk rating were calculated
and presented in fig1 and 2 respectively:

1) Severity measure: percentage of total DDIs
established during the study that is categorized as minor, moderate and major
DDI.

2) Measure of risk: percentage of the total DDIs
that is categorized as; X (Combination should be avoided), D (Combination must
consider therapy modification), C (Combination which must be monitored).

Drug classes that had the most interactions were Antibiotics
(9.9%), Antihypertensives(29.7%), Antidiabetics (14.1%), NSAIDs (4.2%), Diuretics
(21.7%), Antiplatelet (14.7%), Opoid Analgesics (1.3%), Proton pump Inhibitors
(1.1%).

Fig.
1 Drug interactions on the basis of
severity

 

Fig.
2; Drug interactions on the basis of Risk rating

 

DISCUSSION

The
study assessed the prevalence of potential drug interactions in Geriatric
patients. The prevalence of DDIs established was 59.75%, which were prescribed
medications. A wide variation of
epidermilogical data exists for prevalence of DDIs with range between 44.3% and
87.9% (Caribe et al., 2013; Papadpoulos
et al., 2010; Reise et al., 2011 & Romac et al., 1999). Therefore it is important
that more care and attention should be given to the elderly population. It was
observed that there was greater number of the female population and it is in
line with some studies that medication intake is always associated with the
female gender.  The link between age and
polypharmacy is as a result of multiple health problems in old age,
particularly those with life threatening or very bad conditions that require
drug therapy.  In this study, which
involved 400 patient folders, 1925 drugs were prescribed, with an average of
4.82 drugs per patient and a total of eight hundred and sixteen (816) total
recorded DDIs, in which 47 (6.29%) were major interactions, 591 (71.5%) were
moderate interactions and 178 (22.25%)were minor interactions. This
shows that increased concomitant use of drugs coupled with age related decline
in organ function gave rise to high prevalence of drug-drug interactions.
Antihypertensive is the class of drug with the highest number of interactions
and it shows that hypertension was the most chronic disease observed in the
participants. Thus it reflects morbidity and mortality. From the risk rating of DDIs, categories X, D, and C were
found to be 4.9%, 23.8% and 71.3% respectively. Aghajani et al.
conducted an investigation to assess the DDIs in CCU using the Lexi Comp drug
interact found that category C is more (75.03%), followed by B (14.61%), D
(5.42%), X (2.32%) (Hajiet al. 2013).
This implies that therapy must be closely followed up and monitored till the
desired outcome is gotten in order to avoid drug-drug interaction 

The study findings of this research showed that
there is an increased number of drugs prescribed for the geriatric patients,
which leads to higher possibility of Drug Interactions.

CONCLUSION

 The prevalence
of potential drug drug interactions in geriatrics in Nnamdi Azikiwe University
Teaching Hospital was moderately high. Although it is not easy to completely
rule out the possible interactions of drugs, the health care professionals
should look out for commonly prescribed and used drugs which have great
potential of drug interaction. Some measures like adjusting the dose of
medication, making the time of medication use easy, looking out for outcome of
therapy and some complications, taking into account every information given by
the elderly like social history, medication history, mental levels and others should
be taken into consideration.

 

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