Pharmacology Inhalation | CHAPTER-1 | Pharmacology

Pharmacology Inhalation | CHAPTER-1 | Pharmacology

April 2, 2024January 1, 2020

Pharmacology Inhalation – This book covers the entire syllabus of “Pharmacology” prescribed by BNMC- for diploma in nursing science & midwifery students. We tried to accommodate the latest information and topics. This book is an examination set up according to the teachers’ lectures and examination questions.

At the end of the book, previous questions are given. We hope in touch with the book students’ knowledge will be upgraded and flourish. The unique way of presentation may make your reading of the book a pleasurable experience.

Table of Contents

Pharmacology Inhalation

Volatile liquids and gases are given by inhalation for systemic action, e.g. general anaesthetics. Absorption takes place from the vast surface of alveoli-action is very rapid. When administration is discontinued the drug diffuses back and is rapidly eliminated in expired air.

Advantages of inhalation route:

Drugs can be rapidly taken up or eliminated
Much higher concentration is achieved at the site of action
Drugs directly delivered to the site of action
Avoid first pass metabolism
Emergency route
Quick onset of action
Bioavailability 5 to <100%

Disadvantage of inhalation route:

Special apparatus is needed
Irritant drug usually cannot be administered
Prolonged inhalation sometimes cause adverse effects (Oropharyngeal candidiasis with prolong steroid inhalation).

NICE TO KNOW

Important table regarding routes of drug administration

Route of Administration	Absorption Pattern	Advantages	Disadvantages
Oral	Variable; affected by many factors	Safest and most common, convenient, and economical route of administration mixtures Valuable in emergency situations Dosage titration permissible Ideal for high molecular weight proteins and peptide drugs	Limited absorption of sorne drugs Food may affect absorption Patient compliance is necessary Drugs may be metabolized before systemic absorption Injected Strict aseptic techniques needed
Subcutaneous	Depends on drug diluents: Aqueous solution: prompt Depot preparations slow and sustained	Suitable for slow-ion To release drugs Ideal for some poorly soluble suspensions	Pain or necrosis if drug is irritating Unsuitable for drugs administered in largel volumes
Transdermal (patch)	Slow and sustained	Bypasses the first-pass effect Convenient and painless Ideal for drugs that are lipophilic and have poor oral bioavailability Ideal for drugs that are quickly eliminated from the body	Some patients are allergic to patches, which can cause irritation Drug must be highlyiner lipophilic May cause delayed delivery of drug to pharmacological site of action Limited to drugs that can be taken in small daily doses
Rectal	Erratic and variable	Partially bypasses first- pass effect Bypasses destruction by stomach acid Ideal if drug causes vomiting Ideal in patients who are vomiting, or comatose	Drugs may irritate the rectal mucosa Not a well-accepted route
Inhalation	Systemic absorption may occur, this is not always desirable	Absorption is rapid; can have immediate effects Ideal for gases Effective for patients with respiratory problems Dose can be titrated Localized effect to target lungs: lower doses used compared to that with oral or parenteral administration Fewer systemic side effects	Most addictive route (drug can enter the brain quickly) Patient may have difficulty regulating dose Some patients may have difficulty using inhalers
Sublingual	Depends on the drug: Few drugs (for example, nitroglycerin) have rapid, direct systemic absorption Most drugs erratically or incompletely absorbed	Bypasses first-pass effect Bypasses destruction by stomach acid Drug stability maintained because the pH of saliva relatively neutral May cause immediate pharmacological effects	Limited to certain types of drugs Limited to drugs that can be taken in small doses May lose part of the drug dose if swallowed

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Medical and Surgical Nursing | Diploma in Nursing Science and Midwifery