Types of Drug Formulations

Why This Matters

Drug formulation isn't just about putting an active ingredient into a pill—it's a strategic decision that affects everything from bioavailability and patient compliance to manufacturing costs and patent lifecycle management. When you're being tested on pharmaceutical management, you need to understand how formulation choices create competitive advantages, influence pricing strategies, and determine which patient populations a drug can effectively serve.

The underlying principles here connect to broader course concepts: route of administration determines onset and duration of action, release kinetics influence dosing frequency and patient adherence, and delivery technology can extend market exclusivity through reformulation strategies. Don't just memorize what each formulation looks like—know what therapeutic problem each one solves and what business trade-offs it represents.

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Oral Solid Dosage Forms

These are the workhorses of the pharmaceutical industry, representing the majority of prescribed medications. Their popularity stems from manufacturing efficiency, patient convenience, and shelf stability—all factors that reduce costs and improve compliance.

Tablets

• Most common dosage form globally—low manufacturing cost and high patient acceptance make tablets the default choice for oral medications
• Coating technologies serve multiple functions: enteric coatings protect acid-sensitive drugs, while film coatings improve swallowability and brand recognition
• Immediate vs. controlled release options allow companies to reformulate products for extended patent protection and improved therapeutic profiles

Capsules

• Gelatin or HPMC shells encapsulate powders, granules, or liquids—offering formulation flexibility when compression isn't feasible
• Hard capsules vs. soft gels serve different purposes: hard capsules for powders, soft gels for oils and poorly soluble compounds
• Faster disintegration than tablets typically means quicker onset, which matters for pain medications and similar applications

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Liquid and Semi-Solid Formulations

When solid dosage forms won't work—whether due to patient population (pediatrics, geriatrics) or drug characteristics (poor solubility)—liquid formulations fill the gap. The trade-off is typically reduced stability and more complex dosing.

Liquids (Solutions and Suspensions)

• Solutions provide uniform dosing since the drug is completely dissolved—critical for narrow therapeutic index medications
• Suspensions require shaking to redistribute settled particles, introducing dosing variability that manufacturers must address through formulation
• Pediatric and geriatric markets depend heavily on liquid forms, making them strategically important despite higher manufacturing complexity

Topical Preparations (Creams, Ointments, Gels)

• Vehicle selection determines absorption—water-based creams spread easily, oil-based ointments provide occlusion, and gels offer cosmetic elegance
• Local vs. systemic effects depend on formulation design: some topicals are engineered to stay superficial, others to penetrate deeply
• Lower regulatory burden for some OTC topicals creates attractive market opportunities with faster time-to-market

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Parenteral and Bypass Delivery Systems

These formulations bypass the GI tract entirely, solving problems of first-pass metabolism, poor oral bioavailability, and patient non-compliance. They typically command premium pricing but require specialized manufacturing.

Injectables

• Sterile manufacturing requirements dramatically increase production costs and regulatory complexity—but enable delivery of biologics and other molecules that can't survive oral administration
• Rapid onset of action makes injectables essential for emergency medicine and acute care settings
• Formulation options include solutions, suspensions, and emulsions—each with distinct stability and administration characteristics

Transdermal Patches

• Controlled release over 24-72 hours eliminates peak-trough fluctuations and reduces dosing frequency to improve compliance
• Bypasses first-pass metabolism—critical for drugs extensively metabolized by the liver
• Limited to potent, lipophilic molecules with low molecular weight, restricting the candidate pool but creating defensible market positions

Inhalers

• Direct lung delivery achieves high local concentrations with minimal systemic exposure—ideal for respiratory conditions
• MDIs vs. DPIs represent different technology platforms: MDIs use propellants, DPIs rely on patient inspiratory effort
• Device-drug combination products create intellectual property opportunities and switching costs that protect market share

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Advanced Delivery Technologies

These represent the innovation frontier—formulations that solve specific therapeutic challenges through sophisticated engineering. They often support premium pricing and lifecycle extension strategies.

Extended-Release Formulations

• Reduced dosing frequency (once-daily vs. three-times-daily) significantly improves patient adherence, particularly for chronic conditions
• Stable plasma concentrations minimize side effects from peak levels and maintain efficacy during troughs
• Patent lifecycle strategy—reformulating immediate-release products as extended-release versions can extend market exclusivity

Liposomes

• Phospholipid vesicles encapsulate drugs to improve solubility, reduce toxicity, and enable targeted delivery
• Enhanced bioavailability for poorly water-soluble compounds opens development pathways for otherwise undevelopable molecules
• Targeted delivery applications in oncology reduce systemic toxicity—Doxil (liposomal doxorubicin) is the classic example

Suppositories

• Alternative route when oral administration is impossible—useful for nausea/vomiting patients, unconscious patients, or those with swallowing difficulties
• Rectal, vaginal, or urethral insertion allows local or systemic drug delivery depending on formulation design
• Avoids first-pass metabolism for rectally absorbed drugs, improving bioavailability for certain compounds

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Quick Reference Table

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Self-Check Questions

1. Which two formulation types bypass first-pass metabolism while still providing sustained drug release over 24+ hours?

2. A company wants to reformulate an immediate-release tablet to extend patent protection. What formulation strategy would achieve this, and what patient benefit would justify the change?

3. Compare and contrast inhalers and injectables: What therapeutic advantages do they share, and what distinguishes their appropriate use cases?

4. Why might a pharmaceutical company choose to develop a suspension rather than a solution, despite the dosing variability suspensions introduce?

5. If an FRQ asks you to recommend a formulation for a potent, lipophilic drug with extensive hepatic metabolism intended for chronic daily use, which delivery system would you choose and why?