Note introduction to pharmacology - 2

 There are various routes through which a drug
can be administered. Properties of the drug
and the patient’s requirements are the two
factors determining the choice of route in a
patient.
 However, the condition of the patient and
knowledge of advantages and disadvantages of
various routes are of prime importance in
making the selection of best suiting route.

Routes of Drug
Administration
Systemic
Enteral Parenteral
Local
1. Topical
2. Inhalation
3. Instillation
4. Transmucosal

Routes of Drug Administration
Systemic
Enteral
Oral
Sublingual
Rectal
Parenteral
Injections
Inhalations
Transdermal

 Physical & chemical properties of drug - solid/
liquid/gas; solubility, stability, PH, irritancy
 Site of desired action- localized and approachable
or generalized and non approachable
 Rate & extent of absorption from various routes
 Effect of digestive juices & first pass effect
 Rapidity of the desired response –
routine/emergency
 Accuracy of dosage
 Condition of the patient- unconscious, vomiting

 ORAL ROUTE
The most common route of drug
administration. Drug is given through oral
cavity.
ADVANTAGES
› Safe
› Convenient- self- administered, pain free,
non-invasive and easy to take
› Economical - compared to other
parenteral routes
› Usually good absorption - takes place
along the whole length of the GI tract
› No need for sterilization

 ORAL ROUTE
DISADVANTAGES
› Onset of action is slower
› Absorption is irregular & unpredictable
› Some drugs may be destroyed by gastric juices.
Eg. Insulin
› Irritant and unpalatable drugs can’t be
administered
› Can’t give to unconscious and uncooperative
patient
› Some drugs cause irritation and induce vomiting.
› Oral route is not recommended for drug
undergoing extensive FIRST PASS EFFECT.

 SUBLINGUAL/BUCCAL ROUTE
Tablet or pellet containing the drug is
placed under tongue or crushed in
mouth and spread over the buccal
mucosa. Eg. Nitroglycerin, methyl
testosterone.
ADVANTAGES
› Drug absorption is quick
› Quick termination
› First-pass avoided
› Can be self administered
› Economical

 SUBLINGUAL/BUCCAL ROUTE
DISADVANTAGES
› Unpalatable & bitter drugs
› Irritation of oral mucosa
› Large quantities not given
› Few drugs are absorbed

 RECTAL ROUTE
The drug may be given rectally for systemic
effect when the patient is either
unconscious or vomiting. However,
absorption from rectum is irregular and
incomplete and may cause irritation of
rectal mucosa.

 RECTAL ROUTE
Drugs that are administered rectally as a suppository
or enema. In suppository form, a drug is mixed
with a waxy substance that dissolves or liquefies
after it is inserted into the rectum. Ex - Diazepam,
indomethacin, paraldehyde, ergotamine. Enema is
a solution or suspension of the drug in water or
some other vehicle.

ADVANTAGES
› Used in children
› Little or no first
pass effect
› Used in vomiting or
unconscious
› Higher
concentrations
rapidly achieved
DISADVANTAGES
› Inconvenient
› Absorption is slow
and erratic
› Irritation or
inflammation of
rectal mucosa can
occur
RECTAL ROUTE

Direct delivery of drug in to systemic
circulation without intestinal mucosa or
pulmonary alveoli.
ADVANTAGES
› Rapid action
› No first pass metabolism
› Can be used for unconscious and uncooperative
patients, also patients with vomiting and
diarrhoea
› No destruction of drugs in gut fluids
› No food-drug interaction

DISADVANTAGES
› Infection prone
› Need aseptic techniques
› Invasive
› Assistance require
› Pain
› Needs skill
› Anaphylaxis
› Expensive.

 INJECTIONS
› Intramuscular
› Subcutaneous/hypodermic
› Intradermal
› Intravenous
› Intra-arterial
› Intra-cardiac
› Intra-thecal/intra-spinal
› Intraosseous/intra-articular
› Intraperitoneal
› Intrameduallary

 INJECTIONS
› Intramuscular (IM): Injection is made deep into
the muscle tissues like Deltoid, vastus lateralis,
gluteus maximus.
ADVANTAGES
Absorption reasonably uniform
Rapid onset of action
Mild irritants can be given
First pass avoided
Gastric factors can be avoided

 INJECTIONS
› Intramuscular (IM):
DISADVANTAGES
 Only up to 10ml drug can be given
 Local pain and abscess
 Expensive
 Infection & Nerve damage
 Local hematoma can occur
in anticoagulant treated pt.

 INJECTIONS
› Subcutaneous (SC)/hypodermic:
Drug is deposited in loose
subcutaneous tissue. Eg. Insulin,
heparin.
ADVANTAGES
 Self administration possible
 The drug become long acting
DISADVANTAGES
 Irritant drugs can’t be given
 In shock absorption is not
dependable because of
vasoconstriction.

 INJECTIONS
› Intradermal (ID): Drug are injected into
papillary layer of skin i.e. above dermis and
below epidermis. For example tuberculin
injection for montoux test and BCG vaccination.
Here a small amount of drug is administered.

 INJECTIONS
› Intravenous (IV): Drug solution in injected
directly into the lumen of a vein so that it is
diluted in the venous blood. The drug is carried
to the Heart and circulated to the tissues.
ADVANTAGES
Onset of action is quick
Large volume of drug can be given
Irritants can be given by this route

 INJECTIONS
› Intravenous (IV):
DISADVANTAGES
Thromboplebitis
Extravasations of drugs cause severe
irritation, necrosis.

 INJECTIONS
› Intra-arterial: The drug is
injected directly into the arteries
and used in the treatment of
PVDs, diagnostic studies like
angiographies.
›Intra-cardiac: Here the drug is
directly given to the heart. This
route is rarely used, since it
involves several complications.

 INJECTIONS
› Intra-thecal/intra-spinal: Drugs is administered
via an injection into the spinal canal, or into
the subarachnoid space so that it reaches
the cerebrospinal fluid (CSF). Eg. LP.

 INJECTIONS
› Intraosseous/intra-articular:
› Intraosseous infusion (IO) is the process of
injecting directly into the marrow of a bone.
This provides a non-collapsible entry point into
the systemic venous system. This technique is
used to provide fluids and medication when
intravenous access is not available or not
feasible.
› Intra-articular is the process of injecting drug
directly into the joints especially for the
treatment of arthritis.

 INJECTIONS
›Intraperitoneal:
Intraperitoneal injection or
IP injection is the injection of
a substance into the
peritoneum (body cavity).
›Intrameduallary :
Administration of
a drug within the
marrow cavity of a bone.

 INHALATIONS
Gaseous and volatile drugs may be inhaled. They are
then absorbed by pulmonary endothelium and
mucous membrane of the respiratory tract and
reach circulation rapidly. Also, the solutions of drug
particles and the fine droplets are inhaled as aerosol,
eg. Salbutamol. It can produce both local and
systemic effect.

 INHALATIONS
ADVANTAGES
› Rapid absorption
› More effective and less harmful in case of
pulmonary disease.
› First pass metabolism is avoided
› Conveniently controlled blood level of volatile
anesthesia.
DISADVANTAGES
› Irritant gases may enhance the production of
pulmonary secretions.

 TRANSDERMAL
Transdermal is
a route of administrat
ion wherein active
ingredients are
delivered across the
skin for systemic
distribution. Examples
include Transdermal
patches used
for medicine delivery.

 TRANSDERMAL
› Inunction, Adhesive units, Iontophoresis, Jet
Injection and Implantation are some forms of
transdermal drug delivery system.
Inunction Adhesive units

 TOPICAL
 Local Dermal Application: As ointment,
cream, gel, powder, and paste applied on skin
to achieve local action. It can be through
Inunction, Insufflations (administer in the
form of powder, vapour or air into a wound or
body cavity).
 INSTILLATION
Putting a drug in liquid form into body cavity
such as peritoneum, into body orifices as ears,
eyes etc.

 TRANSMUCOSAL
It involves the absorption of drugs across the
mucus membranes. It includes
Sublingual/buccal
Rectal
Nasal

 Check the name on the prescription and
wristband.
 Ideally, use 2 or more identifiers and ask
patient to identify themselves.
 Verify patient’s allergies with chart and
with patient.

 Perform a triple check of the medication’s label
1. When retrieving the medication.
2. When preparing the medication.
3. Before administering medication to patient. Check the
name of the medication, brand names should be
avoided.
 Check the expiry date.
 Check the prescription.
 Make sure medications, especially antibiotics, are
reviewed regularly.
 Never administer medication prepared by another
person
 Never administer medication that is not labelled.

 Check label for medication concentration.
 Compare prepared dose with medication
order.
 Triple all medication calculations.
 Check all medication calculations with
another nurse.
 Verify that dosage is within appropriate
dose range for patient and medication.

 Verify schedule of medication with order.
1. Date
2. Time
3. Specified period of time
 Check last dose of medication given to
patient.
 Administer medication within 30 minutes
of schedule.

 Again, check the order and appropriateness
of the route prescribed.
 Confirm that the patient can take or receive
the medication by the ordered route.

 Check if the patient understands what the
medication is for.
 Inform patient about the desired and side
effects of medication.
 Make them aware they should contact a
healthcare professional if they experience
side-effects or reactions.

Ensure you have the patient consent to administer
medications.
Be aware that patients do have a right to refuse
medication if they have the capacity to do so.
The legally responsible party (patient, parent, family
member, guardian, etc.) for patient’s care has the right to
refuse any medication.
Inform responsible party of consequences of refusing
medication.
Verify that responsible party understands all of these
consequences.
Notify physician that ordered medication is refused and
document notification.
Document refusal of medication and that responsible
party understands consequences.

 Check your patient actually needs the
medication.
 Check for contraindications.
 Baseline observations if required.
 Properly assess patient and tests to determine
if medication is safe and appropriate.
 If deemed unsafe or inappropriate, notify
ordering physician and document
notification.
 Document that medication was not
administered and the reason that dose was
skipped.

After Medication
Has Been
Administered…

 Ensure the medication is working the way
it should.
 Ensure medications are reviewed regularly.
 Ongoing observations if required.
 Assess patient for any adverse side effects.
 Document patient’s response to
medication

 Ensure you have signed for the medication
AFTER it has been administered.
 Ensure the medication is prescribed correctly
with a start and end date if appropriate.
 Document
1. Medication
2. Dosage
3. Route
4. Date and Time
5. Signature and credentials
6. When appropriate, signature of other nurse
checking medication

 In the early 20th century medical science had made
rapid progress in the discovery of drugs. Due to
indiscriminate use of drugs, there was no law to
control unethical practices. It was also the beginning
of the idea of “Profit” rather than service in the use of
drugs. Until 1940, India had no laws to control
manufacture, sale and distribution of drugs.
 In 1940, “The Drug Bill” was passed to regulate the
import, manufacture, sale And distribution of drugs
in British ruled India. The drug act has been
amended many times and now known as Drugs &
Cosmetics act.

 Later the Pharmacy Act (1948) and the Drug
And Magic Remedies Act (1954) was passed.
 The need for Indian Pharmacopoeia was felt
and committee/commission was set up. The 1st
IP was published in 1945.

 Meaning:
Derived from Greek word – Pharmakon – Drug;
poeia – Make. It is the official publication
containing a list of drugs and medicinal
preparations.
 Definitions:
A book describing drugs, chemicals, and medicinal
preparations; especially : one issued by an
officially recognized authority and serving as a
standard
A collection or stock of drugs

 Indian Pharmacopoeia Commission (IPC)
is an autonomous institution of the Ministry
of Health and Family Welfare which sets
standards for all drugs that are manufactured,
sold and consumed in India. The set of
standards are published under the
title Indian Pharmacopoeia (IP) which has
been modelled over and historically follows
from the British Pharmacopoeia.

 Law is a system of rules to establish justice.
The manufacture, distribution and sale of
drugs require specialized knowledge, skill
and expertise; so it must be handled by
well qualified and expert staff.
 Hence there are certain laws and rules
regulating these areas.

Year Name of the Act
1878 The Opium Act
1919 The Poisons Act
1930 The Dangerous Drugs Act
1940 The Drug & Cosmetics Act
1948 The Pharmacy Act
1954 The Drug and Magic Remedies Act
1955 The Medical & Toilet Preparations Act
1985
The Narcotic Drugs & Psychotropic
Substances Act
1995 The Drug Order

 The Opium Act, 1878: it deals with the
cultivation of poppy and the manufacture,
possession, transport, export, import and sale
of opium.
 The Poisons Act, 1919: This act controlled
the possession, import and sale of poisons.
 The Dangerous Drugs Act, 1930: This act
prohibited:
1. Cultivation & collection of opium plant
2. Manufacture of opium products
3. Sale of opium drugs

 The Drug and Cosmetics Act, 1940: In 1940,
The drug act was passed to control operations
related only to Allopathic drugs. Later the act was
amended & it now includes Ayurvedic, Unani.
Siddha & Homeopathic drugs as well as
cosmetics. Hence from 1962 onwards the drug act
is renamed and it regulates the import,
manufacture, sale, labelling and packing of
drugs.
 The Pharmacy Act, 1948: The act extends to the
whole of India except J&K. The act was passed to
make better provision to regulate the profession
of pharmacy. Under this act the Central Council
of Pharmacy was constituted which has a control
over the education in pharmacy.

 The Drugs & Magic Remedies Act, 1954: This act
was passed to control misleading advertisements.
 The Medicinal & Toilet Preparations Act, 1955:
This act was passed to prevent the misuse of alcohol
containing drugs. The manufacture of spirit
containing drugs needs special license.
 The Narcotics Drugs & Psychotropic Substances
Act, 1985: The act totally bans the cultivation,
manufacture, sale, purchase, use/transport of all
narcotics & psychotropic drugs without proper
license.
 The Drugs (Price Control) Order, 1995: Under
Essential Commodities Act, this order was passed so
that the Government has control over the prices of
bulk drugs and drug formulations.

 The concept of Rational Use Of Drug (RUD) is
age old and is evident by the statement made
by Alexandrian Physician Herophilus 300
years B.C. “medicines are nothing in
themselves but are the very hands of god if
employed with reason and prudence.”
 The RUD is based on the rule of right. “The
right drug is given to the right patient in right
dosage at right cost”. It should also fulfil the
‘SANE’ criteria, which means that Safety,
Affordability, Need And Efficiency of the drug
should be considered before prescribing it to
the patient.

Definitions:
 Rational use of medicines requires that
"patients receive medications appropriate to
their clinical needs, in doses that meet their
own individual requirements, for an adequate
period of time, and at the lowest cost to them
and their community". (WHO)
 In simplest words rational use means
“prescribing right drug, in adequate dose for
the sufficient duration & appropriate to the
clinical needs of the patient at lowest Cost

Factors that have precipitated the
realization for RUD are:
 Drug explosion
 Efforts to prevent the development of
resistance
 Growing awareness
 Escalating costs

Few examples of such irrational
combinations are :
 Ibuprofen with PCM
 Diclofenac with Nimesulide
 Ciprofloxacin with Tinidazole

 Therapeutics can be defined as the use of
drugs in the prevention and treatment of
disease. The drug must be administered
appropriately and its beneficial effects and
adverse effects are monitored.
 Depending on the patient’s requirements and
nature of the drug, drug dose are of the
following types
1. Fixed dose
2. Individual dose
3. Loading dose

1. Fixed dose: In case of safe drugs, a fixed dose
of the drug is suitable for most of the
patient’s. Ex. PCM – 650 mg
2. Individual dose: For some drugs with low
safety margin, the dose has to be tailored to
the needs of the patient. Ex. Phenytoin.
3. Loading dose: When immediate drug
response is desired, a large initial dose known
as the loading dose is given to achieve a rapid
minimum effective concentration in the
plasma. Ex. Bolus administration of fluid.

Application of Basic Principles of Therapeutics:
 Patient’s Problem: Take a detailed history of
the illness & drug history of the patient.
 Diagnosis: An accurate diagnosis is a
perquisite for rational therapy.
 Therapeutic objectives: This should be
arrived at from the prognosis of the disease or
relieving a symptom or preventing a disease
or a combination of these.

 Selection of drug treatment: It is divided into
two phases:-
 Determine the options available to treat a health
problem
 Evaluate the drugs on the basis of the following
criteria –
 Efficacy – Based on Pharmacodynamics and
pharmacokinetics parameter.
 Safety – drug with less side effects.
 Suitability – Dosage form should be convenient
and acceptable to the patient.
 Cost - Less expensive drug must be preferred
 Storage conditions – More easily stored

 Start the treatment: Prescribe and start the
treatment. Inform patient about the
beneficial and adverse effects.
 Result of the treatment: It should be assessed
periodically.

 The expiry periods of pharmaceutical
products have meaning only if the products
are stored under proper conditions, otherwise,
products are likely to lose their potency before
the actual date of expiry.

 Every community pharmacy, however large or
small, needs to store and manage its medicine
stocks effectively. There must be systems to
ensure
› Secure storage.
› Clean and correct environmental conditions
during storage.
› Accurate and effective record keeping.
› Effective stock rotation and expiry monitoring.
› Effective fire and theft prevention.
› Effective rodent/ pest control

 STORAGE
The need for proper storage
• The storage of medicines and other products is an
important requirement of Good Pharmacy
Practice.
Appropriate storage of medicines is essential –
Ø To ensure that the potency is maintained.
Ø To prevent deterioration/spoilage/degradation.
Ø To ensure/maintain physical integrity.
Ø To ascertain that the quality and safety is
maintained throughout their shelf life.

 Storage requirements need to be considered
on 2 aspects :
A) Integrity Of Medicines: Medicines Should Be
Stored In Such A Way So As To Maintain
Their Integrity And Potency.
• Maintain the right temperature required.
• Protect from excessive humidity.
• Keep medicines away from direct sunlight.
• Protect from pests and rodents.

 Storage requirements need to be
considered on 2 aspects :
B) Physical location
• Should be easy to locate.
• Accessible.
• Orderly/systematically placed

Storage according to
temperatures is a must,
no matter which pattern
of storage is followed.
Also, within a particular
storage area, segregated
storage may be
maintained. In a
refrigerator, for example,
medicines may be stored
in trays, racks and the
freezer, according to the
temperature required.

An air-conditioned environment where
temperature can be controlled is
recommended for pharmacies. Air
conditioning offers the option of setting the
temperature as per requirements. It is ideal
to have an air conditioner to maintain the
temperature below 25 C, as most medicines
require storage below this temperature. In
the absence of an air conditioner, circulating
fans may be used.

Moisture or humidity can adversely affect
the stability of medicines such as tablets,
capsules, powders. Gelatin capsules become
soft, and swell on absorption of moisture.
The presence of moisture may encourage the
growth of microbes. It is therefore essential
to control humidity.

Whatever pattern of storage is selected, all
the personnel should ensure that
• The stocks are stored in an orderly manner.
• The medicines are kept back in the same
place from where they were removed.
• All medicines are arranged neatly once in a
while.
• The personnel should be careful while
storing the medicines.
• They should not throw the medicines
haphazardly.

Direct storage of cartons on the floor should
be avoided because, besides being an
unhealthy practice, the contents may also be
damaged by moisture.
Store medicines preferably in shelves with
glass shutters for visibility. Closed shelves
further prevent dust from going in, especially
where most pharmacies are located along
busy roads.
Some medicines have to be refrigerated or
stored in a cool or cold place.

Measurement systems –
 Metric: (simple system based on units of
10). The basic units of measurement in the
metric system are the meter (linear), the liter
(volume), and the gram (mass).
 Apothecaries: (based on the weight of one grain
of wheat). The basic unit of weight is the grain
(gr), and the basic unit of volume is the minim
(the approximate volume of water that weighs a
grain) and the inch is a unit of length
 Household: (drops, teaspoons, tablespoons, etc.)
• Most doctors use the metric system

 Dosage calculations are the basic everyday
type of calculations you will be doing on the
ward. They include calculating number of
tablets or capsules required, divided doses,
simple drug dosages and dosages based on
patient parameters, e.g. weight and body
surface area.

CALCULATING THE NUMBER OF TABLETS OR
CAPSULES REQUIRED
 There may be instances when the strength of the
tablets or capsules available do not match the
dose prescribed. Then you will have to calculate
how many tablets or capsules to give the patient.
 A formula can be derived:
Number required = Amount prescribed
_________________
Amount in each tablet or capsule

CALCULATING THE NUMBER OF TABLETS
OR CAPSULES REQUIRED
 Examples:
A patient is prescribed 2 g of flucloxacillin to be
given orally but it is available in 500mg
capsules. How many capsules should you give?
First convert grams to milligrams, multiply by
1,000: 2 g = (2 × 1,000)mg = 2,000mg
2 000
_____ = 4 capsules
500

DOSAGES BASED ON PATIENT
PARAMETERS
Sometimes, the dose required is calculated on a
body weight basis (mg/kg) or in terms of a
patient’s surface area (mg/m2). Using body
surface area (BSA) estimates is more accurate
than using body weight.
WEIGHT: Total dose required = Dose per kg ×
Patient’s weight
SURFACE AREA: Total dose required = Dose per
m2 × Body surface area

DOSAGES BASED ON PATIENT PARAMETERS
EXAMPLES:
WEIGHT
 The dose required is 3 mg/kg and the patient
weighs 68 kg.
3 × 68 = 204mg
SURFACE AREA
 The dose required is 500mg/m2 and the patient’s
body surface area is 1.89m2.
500 × 1.89 = 945mg

DOSAGES BASED ON PATIENT
PARAMETERS

CALCULATING DRUG DOSAGES
 There are 3 primary methods for calculation of
medication dosages; Dimensional Analysis, Ratio
Proportion, and Formula or Desired Over Have
Method. There are several ways of solving this
type of calculation. It is best to learn one way and
stick to it.
 Formula to calculate drug dosages
amount you want
________________ × volume it’s in
amount you’ve got

CALCULATING DRUG DOSAGES
 EXAMPLE
You need to give a patient 125 micrograms of
digoxin orally. You have digoxin elixir 50
micrograms/mL supplied with a dropper
pipette. How much do you need to draw up?
125
__ × 1= 2.5mL
50

INFUSION RATE CALCULATIONS
With infusions, there are two types of infusion
rate calculations to be considered: those
involving drops/min and those involving
mL/hour. The first (drops/min) is mainly
encountered when infusions are given under
gravity as with fluid replacement. The second
(mL/hour) is encountered when infusions
have to be given accurately or in small
volumes using infusion or syringe pumps –
particularly if drugs have to be given as
infusions.

DRIP RATE CALCULATIONS (drops/min)
To do this, you have to calculate the volume to be
infused in terms of drops. This in turn depends upon
the giving or administration set being used.
Giving sets
There are two giving sets:
 The standard giving set (SGS) has a drip rate of 20
drops per mL for clear fluids (i.e. sodium chloride,
glucose) and 15 drops per mL for blood.
 The micro-drop giving set or burette has a drip
rate of 60 drops per mL. The drip rate of the giving
set is always written on the wrapper if you are not
sure.

drops/min =
drops/mL of the giving set × volume of the
infusion (mL)
_________________________________________
number of hours the infusion is to run× 60

 Example:
1 litre of sodium chloride 0.9% (‘normal saline’) is
to be given over 8 hours: what drip rate is
required using a standard giving set (SGS), 20
drops/mL?
20 X 1 000
__________ = 41.67 drops/min (42 drops/min,
approx.)
8 X 60

 Example:
1 litre of sodium chloride 0.9% (‘normal saline’) is
to be given over 8 hours: what drip rate is
required using a standard giving set (SGS), 20
drops/mL?
20 X 1 000
__________ = 41.67 drops/min (42 drops/min, approx.)
8 X 60

Note introduction to pharmacology - 2

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Note introduction to pharmacology - 2