Untitled Quiz

Transdermal Route

• Passive diffusion of drugs across the skin driven by concentration gradient
• Potential benefits: controlled release of drug, steady blood-level profile, user-friendly, convenient, painless, multi-day dosing, improved patient compliance, bypasses GI irritation and partial first-pass inactivation by the liver
• Limitations/risks: skin barrier limits the number of drugs that can be delivered, potential skin irritation, discomfort

Rectal Route

• Prevents destruction of drug by intestinal enzymes or low pH in the stomach
• Bypasses the portal circulation, minimizing biotransformation of drugs by the liver
• Useful for patients who induce vomiting when given orally, are already vomiting, or are unconscious
• Disadvantages: discomfort, inconvenience, and many drugs irritate the rectal mucosa

Subcutaneous (SC) Route

• Advantages: slow absorption, can be used as a depot, rate of absorption can be modified by altering blood flow
• Disadvantages: of little value in peripheral circulatory failure (shock), only small volumes can be accommodated

Intramuscular (IM) Route

• Advantages: more rapid absorption than SC, rate of absorption can be modified by altering blood flow
• Disadvantages: potential infection and/or nerve damage, danger of inadvertent IV administration

Factors Affecting Absorption

• Injection site (blood supply)
• Tissue damage, bruise, less muscle volume
• Others: massage, warm compress, vasodilatation drugs

Inhalation Route

• Provides rapid delivery of a drug across the large surface area of the mucous membranes of the respiratory tract and pulmonary epithelium
• Used for drugs that are gases or those that can be dispersed in an aerosol (e.g., albuterol, corticosteroids)
• Effective and convenient for patients with respiratory complaints (e.g., asthma, COPD)

Intrathecal/Intraventricular Route

• Directly introduces drugs into the cerebrospinal fluid
• Used for treating conditions such as cryptococcal meningitis (e.g., amphotericin B)

Topical Route

• Used when a local effect of the drug is desired
• Examples: clotrimazole for dermatophytosis, tropicamide or cyclopentolate for dilating the pupil and measuring refractive errors

Sublingual Route

• Placement under the tongue allows a drug to diffuse into the capillary network and enter the systemic circulation directly
• Advantages: rapid absorption, convenience of administration, low incidence of infection, avoidance of first-pass metabolism
• Disadvantages: drug taste

Parenteral Route

• Directly introduces drugs across the body's barrier defences into the systemic circulation or other vascular tissue
• Used for drugs that are poorly absorbed from the GI tract (e.g., heparin) and for agents that are unstable in the GI tract (e.g., insulin)
• Used for treatment of unconscious patients and under circumstances that require a rapid onset of action
• Advantages: highest bioavailability, not subject to first-pass metabolism or harsh GI environments
• Disadvantages: irreversible, may cause pain, fear, and infections

Intravenous (IV) Route

• Most common Parenteral route
• Advantages: avoids the GI tract and therefore, first-pass metabolism by the liver, rapid effect and a maximal degree of control over the circulating levels of the drug
• Disadvantages: pain, sepsis, thrombosis, infiltration, anaphylaxis, phlebitis