What are the different types of drug delivery? A Comprehensive Guide

October 9, 2025 •

3 min read

The global pharmaceutical drug delivery market was valued at approximately US$1.9 trillion in 2023 and is projected to grow, with oral delivery methods accounting for over 55% of the market share. Understanding what are the different types of drug delivery is crucial for appreciating advancements in modern medicine.

Quick Summary

An exploration of drug delivery systems, covering the routes of administration and the mechanisms that get medication where it needs to go. It contrasts conventional methods with advanced novel systems.

Key Points

Conventional vs. Novel Systems: Drug delivery is classified into conventional (oral, injectable) and novel systems (targeted, controlled-release).
Oral Route Dominance: The oral route is the most common due to convenience, but it has challenges like first-pass metabolism.
Controlled-Release Benefits: Controlled-release systems maintain steady drug levels, reduce dosing frequency, and improve patient adherence.
Targeted Delivery Precision: Targeted delivery uses carriers like nanoparticles to concentrate drugs at diseased sites, minimizing side effects.
Passive vs. Active Targeting: Passive targeting uses the EPR effect, while active targeting uses ligands to bind to specific cell receptors.
Role of Nanotechnology: Nanocarriers like liposomes and polymeric nanoparticles are key to developing advanced drug delivery systems.
Future is Smart and Personal: The future lies in stimuli-responsive systems, AI-driven personalization, and 3D-printed medications.

Introduction to Drug Delivery Systems

A drug delivery system is an engineered technology designed to transport a pharmaceutical compound within the body to safely achieve its desired therapeutic effect. The primary goal is to control the rate, time, and place of drug release, thereby improving efficacy, reducing side effects, and enhancing patient compliance. The method of administration and the formulation are critical components that determine how a drug interacts with the body. Drug delivery systems can be broadly categorized based on the route of administration and the technology used for release, ranging from traditional pills to sophisticated nanocarriers. The evolution of these systems is driven by the need to overcome challenges like poor drug solubility, enzymatic degradation, and the blood-brain barrier.

Conventional Drug Delivery Systems

Conventional drug delivery includes the most common and well-established methods of administering medication, typically resulting in systemic distribution.

Oral Delivery Oral administration, such as tablets and capsules, is the most common route due to its convenience and cost-effectiveness. Challenges include variable absorption and the first-pass effect, where the liver metabolizes the drug before it reaches systemic circulation.

Parenteral Delivery (Injections) Parenteral routes involve injecting drugs directly into the body. Intravenous (IV) injections provide rapid onset and high bioavailability. Intramuscular (IM) and subcutaneous (SQ) injections offer slower release. This method is invasive and carries risks like infection.

Topical and Transdermal Delivery Topical application is for local effects, while transdermal delivery via patches provides systemic absorption through the skin, bypassing first-pass metabolism. Absorption can be inconsistent.

Pulmonary and Nasal Delivery Inhalation delivers drugs to the lungs for rapid absorption, while nasal delivery can be used for localized or systemic effects. Patient technique can impact delivery consistency.

Novel Drug Delivery Systems (NDDS)

Novel drug delivery systems use advanced technologies to enhance drug efficacy and patient experience.

Controlled-Release Systems These systems release drugs at a predetermined rate to maintain steady drug levels, reduce dosing frequency, and improve compliance. Mechanisms include diffusion, dissolution, osmosis, and swelling.

Targeted Drug Delivery Targeted delivery aims to deliver drugs specifically to diseased tissues. This is achieved through passive targeting (EPR effect in tumors), active targeting (ligands binding to cell receptors), or physical targeting (external stimuli).

Nanotechnology-Based Systems Nanocarriers like liposomes, polymeric nanoparticles, dendrimers, and micelles are used to improve drug solubility and enable targeted or controlled release.

Comparison of Drug Delivery Routes


Route of Administration	Advantages	Disadvantages
Oral	High patient compliance, convenient, cost-effective	Poor bioavailability, first-pass metabolism, variable absorption
Parenteral (IV, IM, SQ)	Rapid onset (IV), 100% bioavailability (IV), suitable for most drugs	Invasive, potential for infection, requires trained personnel (IV)
Transdermal	Bypasses first-pass metabolism, sustained release, fewer side effects	Inconsistent absorption, potential skin irritation, dose limitations
Inhalation/Nasal	Fast absorption, direct targeting to lungs, avoids first-pass effect	Inconsistent delivery due to patient technique, can be irritating

The Future of Drug Delivery

Future advancements include smart, stimuli-responsive systems, AI-driven personalization, 3D printing for customized dosages, microneedle arrays, and nanorobots. These innovations aim to improve treatment effectiveness, safety, and individual tailoring.

Conclusion

Drug delivery has evolved significantly, offering more precise control over medication effects. While conventional methods remain important, novel systems like targeted and controlled-release technologies are improving treatments for various conditions by enhancing efficacy, reducing toxicity, and improving patient quality of life. Ongoing research in nanotechnology and personalized medicine promises even more effective delivery methods in the future.

For further reading, consider exploring resources from the National Institute of Biomedical Imaging and Bioengineering (NIBIB).

Frequently Asked Questions

The oral route, which includes tablets, capsules, and liquids, is the most common and preferred method of drug delivery due to its convenience, cost-effectiveness, and high patient compliance.

Conventional systems, like oral tablets or injections, typically release drugs for systemic absorption without specific targeting. Novel systems use advanced technologies like nanoparticles and controlled-release polymers to target specific sites, regulate release over time, and improve efficacy.

Targeted drug delivery is a method that delivers medication directly to a specific site in the body, such as a tumor, while minimizing its effect on healthy tissues. This is often achieved using carriers like nanoparticles modified with ligands that bind to target cells.

Controlled-release systems regulate drug release over an extended period through various mechanisms. These include diffusion through a polymer, dissolution of a coating, or osmotic pressure, which all work to maintain a constant, effective drug concentration in the body.

NDDS offer several advantages, including increased therapeutic efficacy, reduced side effects by targeting diseased tissues, improved patient compliance through less frequent dosing, and the ability to deliver drugs that would otherwise be degraded by the body.

The first-pass effect, or first-pass metabolism, is a phenomenon where a drug's concentration is significantly reduced after it is absorbed from the gut and metabolized by the liver before it reaches systemic circulation. This can lower the drug's bioavailability.

Nanotechnology uses nanoscale carriers like liposomes, micelles, and polymeric nanoparticles to deliver drugs. These carriers can protect the drug from degradation, improve solubility, and be engineered for targeted and controlled release, enhancing therapeutic outcomes.