The selection of a drug's delivery route depends upon its physicochemical properties, including lipid or water solubility and ionization, as well as the therapeutic requirement, such as immediate or sustained effect. These routes can be divided into three primary categories: enteral, parenteral, and topical.
Enteral delivery involves administering drugs directly through swallowing, sublingual placement, or buccal application. Orally administered drugs predominantly navigate the...

Oral drug delivery is the most common route of administration due to its convenience, cost-effectiveness, and high patient compliance. It enables precise formulation to ensure proper drug dosage and bioavailability. The development of oral dosage forms considers drug properties such as solubility, stability, and absorption to optimize therapeutic efficacy.Tablets, capsules, liquids, and chewable formulations enhance drug stability, mask undesirable tastes, and improve patient experience.

Modified-release dosage forms are designed to address the limitations of drugs with short biological half-lives. These forms maintain stable therapeutic drug concentrations over extended periods, reducing the need for frequent dosing. A consistent drug level helps minimize peak-trough fluctuations, which can reduce adverse effects, lower the risk of drug resistance, and improve overall treatment effectiveness.One common type of modified-release form is the extended-release (ER) formulation. ER...

Drug delivery methods like oral inhalation, nasal sprays, transdermal patches, eye drops, intravitreal injection,  and rectal administration provide localized effects with reduced toxicity.
Oral inhalation and nasal sprays swiftly transfer drugs across the respiratory epithelium's mucosal layer. Inhaled glucocorticoids and bronchodilators directly target lung conditions such as asthma, while fluticasone nasal spray mitigates allergic rhinitis.
Transdermal patches transport drugs...

Conventional oral drug products, termed immediate-release (IR) formulations, are engineered to promptly release their active pharmaceutical ingredient (API) upon ingestion, typically in tablets or capsules. This rapid release often results in swift drug absorption and consequent pharmacodynamic effects, although the timing and intensity can vary depending on the drug's properties. Prodrugs within these formulations require metabolic conversion to activate their pharmacodynamic effects,...

The parenteral route is a critical method of drug administration. It delivers compounds directly into the systemic circulation and bypasses the gastrointestinal tract. This approach is particularly advantageous for drugs that exhibit poor absorption or instability when administered orally.
There are three primary parenteral routes: intravenous (IV), intramuscular (IM), and subcutaneous (SC). The IV route introduces the drug directly into the bloodstream, ensuring immediate action. The IM route...