Drug Administration Routes and Dosage Forms

Drug Administration Routes

• Routes of administration: The entry point for a drug into the body (e.g., oral, injectable, inhalation).
• Enteral: Drugs administered through the gastrointestinal (GI) tract. Examples include tablets, capsules, suppositories, elixirs, and suspensions.
• Parenteral: Drugs administered by any route other than the GI tract. This includes:
  • IV (intravenous): Directly into a vein
  • IM (intramuscular): Into a muscle
  • SC (subcutaneous): Under the skin
  • IO (intraosseous): Into the bone marrow
  • IT (intrathoracic): Into the chest cavity
• Transdermal: Application of a drug using a patch or paste on the skin.
• Inhalation: Breathing in a drug in gas, aerosol, or other forms.
• Topical: Application of a drug directly to a body surface, using forms like powders, lotions, or ointments.

Drug Dosage Forms

• Drug dosage form: The physical state of a drug along with non-drug components. Examples include tablets, capsules, solutions.

Pharmacokinetic Phase

• Pharmacokinetic Phase: The process of how a drug enters, moves, and leaves the body. Factors include absorption, distribution, metabolism, and elimination.

Absorption, Distribution, Metabolism, Elimination

• Absorption: How the drug enters the bloodstream.
• Distribution: How the drug travels to its target, is eliminated, or stored.
• Metabolism (Liver): The body's transformation of the drug into a usable form.
• Elimination (Kidney): How the drug is removed from the body. Often expressed as plasma clearance.

Local vs. Systemic Effects

• Local effects: Drug actions limited to a specific area.
• Systemic effects: Drug actions throughout the body.

L/T Ratio

• L/T Ratio: The proportion of drug reaching the lungs versus the total systemic availability. Formula: (Lung dose) / (Lung dose + GI dose)
• Factors increasing L/T Ratio:
  • Effective drug delivery devices
  • Drugs with high first-pass metabolism
  • Mouth rinsing/spitting
  • Proper use of reservoir devices

Pharmacodynamic Phase

• Pharmacodynamic Phase: How a drug affects the body. Focuses on the drug's mechanism of action and what it does to the body.

Structure-Activity Relationship

• Structure-Activity Relationship: The link between a drug's chemical structure and its effects on the body.

Receptor Interaction

• Receptor: A cell component that interacts with a drug to alter cell function.
• Agonist: A chemical that binds to a receptor and produces a response.
• Antagonist: A chemical that binds to a receptor but does not elicit a response; it blocks the action of other chemicals.

Drug Interactions

• Synergism: Combined drug effects are greater than the sum of individual effects.
• Additivity: Combined effects are the linear sum of individual effects.
• Potentiation: One drug doesn't have an effect in itself, but increases the effect of another.

Metric System Conversions

• Length, Volume, Mass: The metric system uses prefixes for larger and smaller units (e.g., kilo-, centi-).
• Conversion: Moving the decimal point to the left for larger units, or right for smaller units, based on the prefix.

Household Measurement Conversions

• Drops: 16 drops = 1 mL
• Teaspoon: 1 teaspoon = 5 mL = 60 drops
• Tablespoon: 1 tablespoon = 15 mL = 3 teaspoons
• Fluid ounce: 1 fluid ounce = 30 mL, 8 fluid ounces = 240 mL (1 cup)

Dosage Schedules

• Dosage Schedule: Defined doses for specific time intervals, often based on body weight.

Medication Delivery Frequency Abbreviations

• ā: before
• p̄: after
• Q or q: every
• HR or hr or h: hour
• BID: twice a day
• TID: three times a day
• QID: four times a day
• q2h: every 2 hours
• q4h: every 4 hours
• q6h: every 6 hours
• STAT: immediately (time critical)
• PRN: as needed
• QD: daily (less common today)