Dosage Forms

Front 1

What is Pharmaceutics?

Back 1

the
formulation (design), manufacture (fabrication),
stability (expiration), and effectiveness
(evaluation) of pharmaceutical dosage forms
or drug delivery systems

Front 2

What is a dosage form?

Back 2

Dosage form provides a mechanism for the convenient and safe delivery of the accurate and precise dose of a given drug substance

Front 3

Why Do Patients Need a Dosage Form?

Back 3

A dosage form or drug delivery system provides a
mechanism for convenient and safe delivery of the correct
dosage of the drug
. Protection of a drug substance from oxygen and humidity - coated tablets and sealed ampules with an inert gas like nitrogen.
2. Protection of a drug substance from influence of gastric
acid after oral administration - enteric coated tablets.
3. Concealing the bitter, salty, or offensive taste or
odor of a drug substance - capsules and tablets
4. Providing liquid preparations of drugs that are unstable or insoluble in the desired vehicle (solvent) - suspensions (for reconstitution).
5. Providing rate and time-controlled drug action (modified) - sustained or delayed release tablets.
6. Providing optimal drug action from novel dosage from such as topical administration and inhalation therapy.
7. Instantaneous delivery of drug directly into the blood circulation (invasive) - IV bolus and infusion.

Front 4

Factors that Considered Before a Drug Is Formulated Into One or More Dosage Forms

Back 4

Nature of the illness: motion sickness - preventive tablet/patch or therapeutic suppository (scopolamine)
Manner in which it is treated: topical (creams or
lotions) or systemic (tablets and injections)
Likely age of the patient: pediatric and geriatric
Anticipated condition of the patient: comatose
or ambulatory
Stability of the drug: powder for reconstitution (suspension)

Front 5

What Would be the Characteristics of An Ideal Drug Delivery System?

Back 5

An Ideal Drug Delivery System should itself be stable and withstand a stable surrounding:
Physical Stability - prevent polymorphic changes, amorphous-crystalline transitions, prevents light induced degradation (Intro course)
Chemical Stability - against oxidation, hydrolysis (atmospheric moisture, oxygen)
Microbiological Stability - preserve the drug against
microbial spoilage
Provides unit dose precision and Ensures consistent bioavailability e.g.,Procardia XL®
Provides special release characteristics: enteric
coating - releases the drug in the intestine to avoid
degradation of acid sensitive drug provides controlled
release for optimum therapy - e.g. sustained release
tablets
Improves patient compliance - patients feel easy and relaxed
Convenience - convenient to consume, carry and
store
Aesthetics - presents a professional appearance/
pharmaceutical elegant
Improve organoleptic qualities - mask the
offensive odor/ taste of the drug e.g. Glucophage
and Citrical

Front 6

What Factors Lead to the Selection of a Given Dosage Form?

Back 6

Physical, chemical, and biological stability
Organoleptic characteristics of the drug
Nature of illness e.g. coma, seriousness of
the illness, nausea & vomiting
Age of the Patient e.g. elderly and pediatric
patients population
Bioavailability (amount of drug available
at action or receptor site) considerations

Front 7

A slight variation in the dosage form and in the
routes of administrations can result in

Back 7

different
profiles of absorption rate, times of onset,
peak and duration of action

Front 8

Per Oral (po) Route (Most Frequent: advantages and disadvantages?

Back 8

mouth, gets into GIT
(Gastrointestinal tract) via mouth, mainly for
systemic use, some times local action
Advantages: most natural, uncomplicated,
convenient, safe method, a wide range of
pH available for absorption of various
drugs (acidic and basic drugs) through GIT
Disadvantages: slow drug response, chances
for irregular absorption, degradation of certain
drugs due to stomach acid, intestinal enzymes
etc.
Dosage Forms: tablets, capsules, solutions,
syrups, elixirs, suspensions, emulsions, etc.

Note: Solutions are absorbed faster than any
other dosage form. Suspensions, capsules,
tablets must undergo dissolution before
absorption. Tablets are the slowest absorbed,
because they must undergo disintegration prior

Front 9

Sublingual and Rectal Routes

Back 9

Site: beneath the tongue only
systemic
Advantages: quick onset of
action, escapes first pass
effect
Disadvantages: inconvenient,
taste, small dose etc.

Dosage Forms: tablet
Site: rectum mainly local
(soothing of inflamed tissues) some
times systemic
Advantages: may escape first
pass effect, useful in infant,
elderly, comatose and
uncooperative patients,
escapes acid degradation of
stomach
Disadvantages: inconvenient,
chances of irregular
absorption
Dosage Forms: solutions,
ointments, suppositories e.g.

Front 10

Parenteral (Other Than the Intestines), Topical and Transdermal Routes

Back 10

Site: other than GIT (by injection),
only systemic
Primary Routes: subcutaneous,
intramuscular, and intravenous
Advantages: rapid predictable
absorption, can deliver drugs that
are poorly absorbed from GI tract
or degraded in GI tract, escapes
first pass effect, useful in infant,
elderly, comatose and
uncooperative patients
Disadvantages: more expensive,
no retrieval, requires trained
personnel (IV nurses)
Dosage Forms: sterile solutions
and suspensions e.g., Humalog
Pen® (in diabetes)
Site: skin surface, local action
Advantages: convenient, can be removed,
local action
Disadvantages: can be messy
Dosage Forms: powders, ointments,
pastes, creams, lotions, sprays

Site: skin surface, systemic delivery
Advantages: convenient, can be removed,
escapes first pass effect, slow continuous
delivery of drug
Disadvantages: expensive, only low mol.
wt. drugs with high partition coefficient
(Ka) are suitable for transdermal
formulations
Dosage Forms: Transdermal patches
discs, iontophoretic, sonophoresis
techniques and more
e.g. Hydrocortisone® (as cream and
ointment) and Orthro-Evra® Patch
(menopause- hormonal disbalance)

Front 11

What happens to a Drug after it is Administered to a Patient?

Back 11

After administration (mostly orally or other routes),
a drug substance gets absorbed through a
membrane(s) or if administered instantaneously as
IV (intravenous) gets directly into the systemic
circulation (blood)
Then the absorbed drug substance gets into the
blood and tissues and distributed throughout the
body tissues and fluids
Afterwards absorbed drug substance is
metabolized in the liver and passed out (excreted)
the body system through different channel mainly
kidneys

Front 12

Bioavailability?

Back 12

Bioavailability: The rate and extent to which a drug
substance is absorbed from a drug product (a dosage form)
and becomes available at absorption site of drug action
The following oral dosage forms are ranked here based on
their bioavailability from fastest to slowest:
Fastest Availability Solutions
Suspensions
Capsules
Tablets
Coated Tablets
Slowest Availability Controlled Release
Formulations (slow release
or modified release)

Front 13

Bioavailable Fraction (F)

Back 13

The fraction of administered dose, that actually gets into the
BLOOD (systemic circulation) as intact (unchanged) drug to
produce clinical effect (drug action).
- unitless (a fraction term

Front 14

What are some reasons for F<1?

Back 14

1. Poor solubility and incomplete dissolution
2. The drug is not completely absorbed through the gastrointestinal tract (GIT- ABSORPTION: is the extent to which intact drug is absorbed from the gut lumen into the portal-systemic circulation).
3. Decomposition in the intestines
4. The drug is transformed in the intestine to a metabolite*
5. The drug is metabolized or eliminated by the liver: is the extent to which a drug is removed by the liver during its first passage through the liver after absorption prior to reaching the systemic circulation (blood). This is also called first-pass metabolism or first-pass effect.

Front 15

What are Some Extravascular Routes of Administration?

Back 15

Extravascular routes are:
buccal   
per oral (PO)
per rectal (PR)-Superior hemorrhoidal vein
intramuscular (IM)
subcutaneous (SC OR SQ)
sublingual (SL)
transdermal (TD)

Front 16

First Pass Effect (or first pass metabolism)

Back 16

The blood draining those sites (PO and PR) happens to
flow directly through the liver BEFORE getting to the
general (systemic) circulation

Front 17

Non-First Pass Routes

Back 17

The blood draining those sites (buccal, intramuscular,
subcutaneous, sublingual, transdermal) flows directly
to the general circulation first, not the liver
The liver removes no portion of the drug before
reaching general circulation