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PHPR 802 Pharmaceutics and Biopharmaceutics > Dosage Form Considerations Lecture 1 > Flashcards

Dosage Form Considerations Lecture 1 Flashcards

1
Q

How would you define “drug”?

A

A drug is defined as an agent intended for use in the diagnosis, mitigation, treatment, cure, or prevention of disease in humans or other animals

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2
Q

Why do we need different types of dosage forms?

A

Drug delivery

Stability

Patient Compliance

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3
Q

Drug Delivery

A

Safe and convenient delivery of accurate dosage of a drug

Examples:
- To administer a high dose of insoluble drug in liquid dosage form (e.g. emulsion, suspension)
- To provide optimal drug action from topical administration sites (e.g. ointments, creams, transdermal patches, ophthalmic, Otic, and nasal routes)
- To provide delivery of drugs by insertion into one of the body’s orifices (e.g. suppositories)
- To administer drug directly into the body tissues (e.g. injections)
- To provide optimal drug action by inhalation therapy (e.g. aerosols)
- To provide controlled drug action (e.g. sustained release tablets, patches)

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4
Q

Stability

A

Examples:
- To protect the drug from destructive influences of atmospheric oxygen and humidity (e.g. coated tablets, sealed ampules, etc.)
- To protect from the destructive influences of gastric acid during oral administration (e.g. enteric-coating)
- cellulose acetate phthalate, Eudragit L100-55 (polymers for enteric coating)

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5
Q

Patient Compliance

A

Examples:
- To mask the unpleasant taste of odor of drug substance (e.g. flavored syrup, coated tablet or capsule)
- To ensure drug delivery to pediatric and geriatric patients (e.g. solution, suspension, emulsion)

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6
Q

Physicochemical Properties of the drug

A

Physical Description

Microscopic Examination

Particle Size

Polymorphism

Solubility

Dissolution / Dissociation

Partition Coefficient

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7
Q

Physical Description

A

Physical state of the drug:
- Solid
- Liquid
- Gases

  • Majority of the drugs are available in solid form
  • Liquid drugs (nitroglycerin, propofol, methyl salicylate)
  • Gases (perfluorocarbons)
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8
Q

Liquid state

A

liquid state processed into different dosage forms

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9
Q

Gas state

A

Microbubbles are designed to deliver gases such as perfluorocarbons for ultrasound mediated diagnosis

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10
Q

Polymorphism

A

Crystalline forms with the SAME CHEMICAL COMPOSITION but DIFFERENT INTERNAL STRUCTURES (packaging, conformation, etc.)

Polymorphism can result in changes in the physicochemical properties of a drug
- Solubility
- Melting Point

Some chemicals exist in a non-crystalline or amorphous state

All of these factors can ultimately affect the bioavailability of a compound

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11
Q

Particle Size

A

Particle size can affect:
- Dissolution rate (surface area effect; affects solubility and absorption)
- Bioavailability
- Taste
- Color
- Stability
- Flow characteristics
- Sedimentation rates

One can calculate the decrease in particle size necessary to increase solubility

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12
Q

Solubility

A

One of the most important physicochemical properties of the drug
- Drugs need to have some degree of aqueous solubility in order to be absorbed across biological membranes

Drug solubility can be affected by:
- Chemical structure
- Particle size
- pH

Examples:
- Indomethacin = -COOH
- Chlorpromazine = tertiary amine
- Oxytetracycline = -OH and tertiary amine

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13
Q

Dissolution

A

Factors affecting dissolution
- Particle size (surface area)
- Chemical nature of the drug (Base/Acid/Salt/Neutral)

Thus, dissolution can affect the pharmacokinetics of the drug
- Overall bioavailability
- Onset of activity
- Duration of action
- Efficacy

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14
Q

Dissociation Constant

A

Can impact drug solubility, partitioning, and ADME

An important consideration in the characteristics of dosage form is the extent of dissociation / ionization, many drugs are ionizable
- The degree of ionization affects pharmacokinetics, specifically absorption (ex. NH3 vs. NH4+)
- The degree of ionization is significantly affected by the pH

In certain formulations, the pH of the vehicle is maintained for solubility / stability
- The pH also may affect the absorption, so these factors must be considered when formulating a drug product

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15
Q

Partition Coefficient

A

Measure of the lipophilicity of a compound

It is helpful in estimating how a drug will behave in the physiological environment

If a given a mixture of two immiscible liquids (one oil and one water), a drug placed in the mixture will distribute between the 2 phases until an equilibrium exists

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16
Q

Drug Stability

A

Prior to their use, drugs should possess:
- Chemical stability
- Physical stability
- Metabolic stability
- Microbiological stability

The most common mechanisms of drug degradation are:
- Hydrolysis = reaction with water molecules to yield an inactive compound
- Oxidation = loss of electrons leading to an inactive compound
- Autoxidation = reaction with atmospheric oxygen
- Photooxidation

17
Q

Inactive Pharmaceutical Ingredients OR Excipients

A

Virtually all pharmaceutical preparations contain additional ingredients besides the active drug substance

Other compounds are added to the drug for a variety of reasons (there MUST be a reason)
- Drug stability
- Improve taste
- Enhance dissolution / absorption
- Preservatives to retard antimicrobial growth
- Diluents/fillers to increase bulk of the preparation

18
Q

Routes of Administration

A

Route of administration impact the time required for the onset of drug action and dosage form design

19
Q

Intravenous (IV)

A

30-60 seconds

20
Q

Intraosseous

A

30-60 seconds

21
Q

Inhalation

A

2-3 minutes

22
Q

Sublingual

A

2-3 minutes

23
Q

Oral

A

30-90 minutes

24
Q

Rectal

A

5-30 minutesT

25
Q

Transdermal

A

Variable (minutes to hours)

26
Q

Asthma / Cystic Fibrosis / COPD

A

Route of Administration: Inhalation

Examples:
- Aerosol
- Dry Powder Inhalers

27
Q

Superficial Skin Infection / Acne

A

Route of Administration: Dermal

Examples:
- Creams
- Gels
- Ointments

28
Q

Inflammatory Bowel Disease

A

Route of Administration: Oral / Rectal

Examples:
- Pills
- Suppositories
- Enema

29
Q

Early-Stage Bladder Cancer

A

Route of Administration: Intravesical (into the bladder)

Examples:
- Solution
- Gel
- Devices

30
Q

Vaginal Infections

A

Route of Administration: Vaginal

Examples:
- Gel
- Cream
- Ointment

31
Q

Contraception

A

Route of Administration: Intra-uterine / Intra-muscular / Vaginal

Examples:
- Implants
- Rings
- Microparticles

32
Q

Ovarian Cancer

A

Route of Administration: Intravenous / Intraperitoneal

Examples:
- Solution
- Gel
- Microparticles

33
Q

Patient

A

Age

Physical condition

Disease type and severity

Patient condition
- Compliant / Non-compliant / Conscious / Vomiting

34
Q

Biopharmaceutical Properties of the drug

A

Permeability

Pharmacokinetics (PK)
- Absorption, Distribution, Metabolism, Excretion

Bioavailability

Dose (Potency)

35
Q

Permeability

A

Transport of the drug across biological membrane

BCS Classification System

Class I = easy to formulate in various dosage forms
- High solubility
- High permeability
- Example: Metoprolol

Class II = formulate dosage form that can improve drug solubility
- Low solubility
- High permeability
- Example: Celecoxib

Class III = formulate dosage form with permeation enhancers
- High solubility
- Low permeability
- Example: Acyclovir

Class IV = formulate dosage form with solubility and permeation enhancers
- Low solubility
- Low permeability
- Example: Paclitaxel

36
Q

Drug Absorption

A

Very important property that governs drug development and dosage form design

Drug absorption is dependent on the physicochemical properties of the drug, drug permeability, site of absorption and the route of administration

Right drug delivery strategy and proper choice of route of administration could help in improving drug absorption

37
Q

Drug Metabolism

A

Pre-systemic

Systemic

Drugs that are extensively metabolized after oral administration are typically administered via other routes of administration and require suitable dosage form design

38
Q

Bioavailability

A

% bioavailability = ( area under the curve (AUC) of oral dose / area under the curve (AUC) of IV dose) x 100

Oral bioavailability of the drug is one of the major considerations in drug development and dosage form design

39
Q

Drug Dose

A

High dose drugs
- Tablets, powder/granules, suspension
- Limitations on the drug dose that can be delivered via certain routes
- Consider change in the dosage form (speed of processing, volume of process)

Very potent drugs
- Consider accuracy and uniformity of dose in the dosage form

PHPR 802 Pharmaceutics and Biopharmaceutics (4 decks)

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