Pharmaceutical Dosage Forms

Solid Oral Dosage Forms

• Accurate dose, less bulky, longer beyond use date, more palatable, and special release characteristics
• Cons: more specific dosing, easier to swallow, and faster onset of action

Controlled Release Dosage Forms

• Pros: less fluctuation in drug blood levels, frequency reduction in dosing, enhanced convenience and compliance, and reduction in adverse side effects
• Cons: loss of flexibility in adjusting the dose and inability to manipulate administration

Buccal and Sublingual Delivery

• Pros: avoidance of first pass effect and rapid onset of action
• Cons: avoidance in patients with oral cavity injury, avoiding eating/drinking until medication dissolves completely

Rectal Delivery

• Pros: lower first pass effect than oral administration, alternate oral route if patient is unable to take by mouth
• Cons: irregular and unpredictable absorption, embarrassment or discomfort for patient or caregiver, and avoidance in patients with immunosuppression or increased risk of bleeding

Transdermal Delivery

• Only a small part of the skin needs to be utilized, can be applied to different areas of the body at each dosing interval, and allows skin to recover
• Epidermis of the skin is a barrier to drug absorption, provides slow permeation resulting in consistent drug levels for extended periods

Pulmonary Delivery

• Used mostly for local delivery of drugs for asthma and chronic obstructive pulmonary disease
• Attributes of the lungs make this route advantageous: large surface area, well supplied with blood vessels, and the drug passes directly into the bloodstream with a rapid effect
• The size of particles administered by means of inhalation influences the part of the lung which they reach

Intramuscular Injection

• Pros: sustained effects, suspension allows a slow release, and solution allows a rapid release
• Cons: inadvertent subcutaneous administration, pain/patient anxiety, risk of nerve injury, and avoidance in patients with increased bleeding tendency

Subcutaneous Injection

• [No specific points mentioned]

Intravenous Administration

• Pros: can administer drugs destroyed or inactivated in GI tract or with poor bioavailability, and rapid onset of action
• Cons: removal after inadvertent overdose is more difficult, more expensive, administration by trained professional, and infection risk

Importance of Dosage Forms

• Dosage forms are necessary to provide accurate dosing, convenience of administration, and protect the drug
• Dosage forms may control the rate of drug release, mask the taste of the drug, separate incompatible ingredients, etc.

Routes of Drug Administration with Corresponding Dosage Forms

• Oral: syrups, elixirs, emulsions, tablets, oral disintegrating tablets, sustained-release tablets, enteric-coated tablets, capsules, softgels
• Rectal: creams, ointments, gels, suppositories, aerosol foams, enemas
• Vaginal: creams, ointments, gels, suppositories
• Topical: creams, ointments, gels, transdermal patches, lotions
• Colonic: rectal foams
• Otic: aqueous drops, oily drops
• Nasal: creams, ointments, gels, drops, sprays, metered-dose sprays
• Pulmonary: metered-dose inhalers, dry powder inhalers, capsules for dry powder inhalation, nebulized solutions
• Intravenous: aqueous solutions, oily solutions, suspensions
• Intramuscular: aqueous solutions, oily solutions, suspensions
• Subcutaneous: aqueous solutions, aqueous suspensions

Pharmacology

• Innovative drug delivery systems can supply drugs to organs difficult to reach by conventional routes, without causing systemic toxicity.

Drug-Receptor Interactions

• Receptors are protein molecules including enzymes, transporters, and ion channels where a ligand (specific endogenous neurotransmitter/hormone or an external pharmacological agent) binds to, resulting in a cellular response.
• Orphan Receptors are receptors for which the ligand remains unknown.
• Ligand is an ion or molecule that forms a complex with a biomolecule to serve a specific biological purpose.

Endogenous Ligands

• Neurotransmitters (NT): chemical messengers signaling across a synaptic cleft, such as Acetylcholine (Ach), Epinephrine (EPI), and Norepinephrine (NE).
• Hormones (peptide): secreted from neuroendocrine cells into the blood to signal at distant cells and tissues, such as Aldosterone, Insulin, Nerve growth factor (NGF), and Thyroid hormone (TH).

Pharmacodynamics

• A drug is a chemical agent that selectively interacts with specific target molecules (i.e., receptors) to alter their specific physiological functions.
• Agonist: a drug that activates receptors to result in either stimulation or inhibition of the function of various types of cells and organs.
• Antagonist: a drug that prevents receptor activation by agonists.

Factors Contributing to Drug Effect

• Drug dosage: the effect of a drug increases with an increased amount of drug up to the point of receptor saturation.
• Number of Receptors: receptors may be differentially expressed in one tissue to the next and, therefore, mediate different levels of biological responses.
• Disease states: disease states can affect drug pharmacology.
• Drug Efficacy/Intrinsic activity: the ability to activate or block a receptor, which is the maximum effect a drug can produce regardless of the dose.
• Drug Potency/Affinity: the rate of drug-receptor binding and drug-receptor release, which is the amount of drug needed to produce a particular effect.

Sub-Disciplines of Pharmacology

• Pharmacodynamics: effects and mechanisms of drug action, including drug-receptor interactions, dose-response relationships, and signal transduction.
• Pharmacokinetics: movement of a drug throughout the body, including absorption, distribution, metabolism, and excretion.
• Pharmacogenetics: genetic factors play a role in the rate of drug metabolism, drug-induced toxicity, and drug-induced allergies.

Drug Administration

• Drug treatment requires getting a drug to its specific target site or sites in tissues where the drug has its action.
• The process of administration involves introducing the drug into the body, sometimes far from the target site.