Untitled Quiz

Pharmacology for Nursing

• Pharmacology is the drug science.
• It includes the mechanism of action, pharmacological effects, therapeutic uses, adverse effects, and other drug information.

General Pharmacology

• General pharmacology includes pharmacokinetics and pharmacodynamics.
• Pharmacokinetics: Deals with processes undergone by a drug after administration, including absorption, distribution, biotransformation, and excretion.
• Pharmacodynamics: Studies drug action on the body, including receptor interactions, dose-response relationships, and therapeutic/toxic mechanisms.

What is a Drug?

• A drug is a chemical substance used for disease prevention, diagnosis, and treatment.

Pharmacokinetics: Drug Absorption

• Drug absorption is the transfer of a drug from its administration site to the bloodstream.
• Mechanisms of drug absorption:
  • Passive/Lipid Diffusion: Occurs with lipid-soluble drugs.
  • Filtration/Aqueous Diffusion: Occurs with water-soluble drugs, passing through aqueous channels or pores between cells. The blood-brain barrier (BBB) and placental barrier prevent water-soluble drugs from crossing.
  • Active Transport: Requires energy and a carrier protein, features selectivity, saturability, and competition.
  • Pinocytosis (Endocytosis): Applicable to high molecular weight drugs like iron, hormones, and vitamin B12.

Factors Affecting Drug Absorption

• Drug-related factors: Lipid solubility, ionization, molecular weight, dosage form, concentration.
• Patient-related factors: Route of administration, blood supply, health status, gastrointestinal (GI) motility, presence of other drugs, presence of food.

Routes of Drug Administration

• Classification:
  • Enteral: Related to the gastrointestinal tract (e.g., oral, sublingual, rectal).
  • Parenteral: Away from the gastrointestinal tract (e.g., injections, topical, inhalation).

Oral Route

• Advantages: Safe, economical, easy.
• Disadvantages: Delayed onset of action, complex formation with food, destruction by stomach acid or enzymes, inactivation by the liver, unsuitable for emergencies or unconscious/uncooperative patients.

Dosage Forms (Oral)

• Oral drops, syrup, suspensions, capsules, tablets, effervescent sachets.

Special Types of Tablets

• Enteric-coated tablets, sustained-release tablets (SR), colored tablets, effervescent tablets, chewing tablets, lozenges.

Enteric-Coated Tablets

• Resist dissolution in the stomach, dissolving in the intestines.
• Advantages: Avoid stomach irritation, prevent gastric acid destruction of drug, mask bitter taste.

Sustained-Release Tablets (SR)

• Release and absorb drug in stages over a prolonged period.
• Give extended duration of action.

Sublingual Route

• Advantages: Rapid onset, bypasses first-pass liver metabolism.
• Disadvantages: Not suitable for all drugs, typically used for nitrates.

Rectal Route

• Advantages: Suitable for unconscious patients, presence of vomiting, 50% of drug bypasses liver.
• Disadvantages: Not suitable for diarrhea, irritation possible. Dosage forms (rectal): Suppositories, enemas (evacuant or retention).

Injections: Intravenous

• Advantages: Very rapid onset, proper dose adjustment, drug remains in active form (no liver or acid destruction).
• Disadvantages: More expensive, needs aseptic conditions, painful, requires a patent vein, difficult to eliminate drug if toxicity occurs, not suitable for suspensions and oily solutions.

Injections: Intramuscular (IM)

• Advantages: Similar to IV but suitable for moderate volume drugs and irritant drugs needing deep injection. Suitable for suspensions and oily solutions.
• Disadvantages: Slower onset than IV, limited volume, possibility of hematoma with anticoagulants.

Injections: Subcutaneous (SC)

• Advantages: Prolonged duration of action, suitable for suspensions and oily solutions, appropriate for insulin and some implants.
• Disadvantages: Slow onset, unsuitable for large volumes and irritant drugs (pain, necrosis).
• Absorption influenced by massage/hot/cold fomentation, vasoconstrictors.

Injections: Intrathecal

• Used for high concentrations of drugs in cerebrospinal fluid (CSF), injection of antibiotics, spinal anesthesia, and diagnosis of CNS disorders via CSF withdrawal.
• Requires special precautions to avoid nerve injury and infection.

Inhalational Route

• Suitable for volatile compounds, gases, and aerosols.
• Local or systemic effects, rapid onset due to large absorption area.
• Self-administration possible.
• Disadvantages: Irritant drugs unsuitable, difficult dose adjustment, specialized equipment often needed.

Topical Route

• Applied to skin or mucous membranes.
• Provides high local concentrations with limited/no systemic effects.
• Some drugs can absorb systemically (e.g., transdermal patches).
• Disadvantages: Systemic absorption can occur, especially with damaged skin, injury or inflammation, highly lipid-soluble drugs.

Dosage Forms (Local)

• Drops (eye, nasal, ear), ointments (dry skin), creams (wet skin), lotions, transdermal patches.

Nursing Implications

• IV solutions must be sterile, aqueous, and free of particulate matter, turbid solutions are prohibited IV.
• Suspensions must be shaken prior to use.
• Sustained release tablets should not be crushed.