ceutics 2

Module 3

Pharmaceutics Part II

Objectives

1. Understand the various routes of drug administration and dosage forms developed for veterinary medicine; 2. Identify and describe the physical and chemical characteristics of various pharmaceutical dosage forms (e.g., tablets, capsules, syrups, ointments); 3. Describe the different specialized dosage forms and delivery systems; 4. Understand the importance of quality in drug formulation.

Biopharmaceutics

Involves the formulation, dissolution, stability, and controlled release of drugs.

Biopharmaceutics — Relationship with Pharmacokinetics and Pharmacodynamics

Integrates with pharmacokinetics (ADME) and pharmacodynamics (concentration-effect relationships).

Dosage Formulation

A combination of an active ingredient with excipients to create a specific dosage form.

Dosage Form — Importance

Determines the route of administration and influences drug efficacy and safety.

Pharmacokinetic-Pharmacodynamic (PK-PD) Models

Link between drug concentration in systemic circulation and receptor interaction.

PK-PD Models — Purpose

Provide the basis for dose optimization to achieve desired therapeutic outcomes.

Challenges in Veterinary Drug Delivery

Species diversity, body size variations, husbandry practices, seasonal changes, and economic factors.

Innovative Solutions in Veterinary Drug Delivery

Topical spot-on formulations, microencapsulation, and controlled-release systems for ruminants.

Oral Route of Administration

Widely used in companion animals (dogs, cats) and food animals (cattle, pigs, poultry).

Oral Dosage Forms — Liquids

Solutions, suspensions, emulsions, elixirs, and syrups.

Oral Dosage Forms — Semisolids

Pastes.

Oral Dosage Forms — Solids

Tablets, capsules, powders, granules, premixes, and medicated blocks.

Advantages of Oral Dosage Forms

Convenient administration and systemic effects through GI absorption.

Oral Dosage Forms — Examples

Tablets for dogs, granules in rations for horses, and premixes for poultry.

Challenges and Considerations of Oral Dosage Forms

Absorption variability, drug stability problems, and the need for careful pharmaceutical formulation to ensure efficacy.

Absorption — Oral Dosage Forms

Absorption rates can vary.

Drug Stability — Oral Dosage Forms

Acid-labile drugs may be destroyed in the stomach.

Formulation Requirements — Oral Dosage Forms

Careful pharmaceutical formulation is needed to ensure efficacy.

Parenteral Route

Any non-oral route of administration.

Four Main Parenteral Routes

Intravenous (IV), Intramuscular (IM), Subcutaneous (SC), and Intra-articular (IA).

Injectable Preparations — Sterile Solutions

Use water for injection or alternative solvents.

Injectable Preparations — Excipients

Antioxidants, antimicrobial preservatives, buffers, chelating agents, inert gases, and tonicity-adjusting agents.

Injectable Preparations — Sterility

Injectable preparations require sterility and avoidance of pyrogens.

Suspensions — Injectable Dosage Form

An injectable dosage form; example: procaine penicillin G.

Factors Influencing Drug Release from Injectable Suspensions

Viscosity and particle size.

Emulsions — Injectable Dosage Form

Can be oil-in-water or water-in-oil emulsions.

Propofol

Example of an injectable emulsion.

Dry Powders — Injectable Dosage Form

Require reconstitution before administration.

Dry Powders — Common Use

Commonly used in vaccines through freeze-drying (lyophilization).

Intramammary Infusions

Used in treating mastitis in lactating and nonlactating cows.

Intramammary Infusions — Key Consideration

There are key differences between formulations used for intramammary infusion.

Intravaginal Devices

Include Controlled Internal Drug Release (CIDR) devices, Progesterone-Releasing Intravaginal Devices (PRIDs), and vaginal sponges.

Intravaginal Devices — Use

Used in estrus synchronization in sheep, goats, and cattle.

Implants — Examples

Weight gain and feed conversion implants; reproductive performance enhancers.

Reproductive Performance Enhancers — Examples

Deslorelin for mares and testosterone for wethers.

Implants — Legal Consideration

Extralabel use for growth promotion is not legal in the US.