Systemic delivery of polypeptide drugs through ocular route

The administration of drugs via parenteral routes allows for direct drug introduction into the systemic circulation, resulting in high bioavailability because the medication bypasses the harsh conditions of the gastrointestinal tract and hepatic metabolism.
The intravenous route (IV) of drug administration can be further categorized into two types. The bolus injection administers the entire dose rapidly, while an intravenous infusion slowly delivers smaller doses steadily.
The IV route is often...

Indirect-acting cholinergic agonists, or anticholinesterases, enhance the body's cholinergic activity by inhibiting acetylcholine's breakdown. They are categorized as reversible or irreversible agents based on their mechanism of action. They are further classified into short-acting, intermediate-acting, and long-acting agents based on their duration of action.
Reversible agents containing quaternary amines, such as neostigmine and edrophonium, are not easily absorbed orally because they are...

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 gastrointestinal...

The enteral drug administration involves three primary routes: oral, sublingual, and buccal. Oral ingestion is the most prevalent, safe, economical, and convenient method for drug administration. However, it has certain drawbacks, including limited absorption due to the drug's low water solubility or poor membrane permeability, possible emesis from GI mucosa irritation, destruction of drugs by digestive enzymes or low gastric pH, and irregular absorption along with food or other drugs.
Drugs in...

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...

Ophthalmic drug delivery faces major limitations due to poor absorption across the corneal membrane. This process is primarily driven by diffusion and is influenced by two main factors: the physicochemical properties of the drug and tear drainage. Most ophthalmic drugs, such as pilocarpine, epinephrine, atropine, and local anesthetics, are weak bases. They are typically formulated at an acidic pH to enhance chemical stability. However, this leads to high ionization, reducing their ability to...