Strengths/dose, dosage forms, routes of administration, special handling and administration instructions, and duration of drug therapy

What Are Drug Strengths?

Drug strength refers to the amount of the active pharmaceutical ingredient (API) present in a specific dosage form. It is typically expressed in units such as milligrams (mg), micrograms (mcg), grams (g), or international units (IU).

Examples:

Acetaminophen: 500 mg tablet
Insulin: 100 IU/mL
Levothyroxine: 25 mcg tablet

What Is a Dose?

A dose is the specific amount of a drug prescribed for a patient to take at one time or over a specific period. It is based on factors such as the patient’s age, weight, medical condition, and kidney/liver function. Examples:

A patient may be prescribed 500 mg of acetaminophen every 6 hours for pain relief.
A child may require 10 mg/kg of amoxicillin for an infection.

Key Considerations for Pharmacy Professionals

Verification of Strength and Dose:

Always verify the strength of the medication and ensure it matches the prescribed dose.
For example, if a prescription reads “amoxicillin 500 mg,” ensure the dispensed tablets are 500 mg each.

Unit Conversions:

Be proficient in converting units (e.g., grams to milligrams, micrograms to milligrams) to avoid errors.
Example: 1 g = 1000 mg; 1 mg = 1000 mcg.

Patient-Specific Factors:

Adjust doses for pediatric or geriatric patients, as well as those with kidney or liver impairment.

Dosage Forms:

Understand how different dosage forms (e.g., tablets, liquids, injections) affect the strength and dosing instructions.
Example: A liquid formulation may require measuring an exact volume (e.g., 5 mL) to deliver the correct dose.

Dosage Forms

Dosage forms are the physical forms in which drugs are delivered to the body. They are designed to ensure stability, efficacy, and patient compliance.

Solid Dosage Forms:

Tablets: Compressed powders (e.g., ibuprofen 200 mg).
Capsules: Gelatin shells containing powder or liquid (e.g., amoxicillin 500 mg).
Powders/Granules: Often reconstituted into liquids (e.g., oral rehydration salts).

Liquid Dosage Forms:

Solutions: Homogeneous mixtures (e.g., cough syrups).
Suspensions: Particles dispersed in liquid (e.g., amoxicillin suspension).
Emulsions: Mixtures of oil and water (e.g., lipid-based injectables).

Semi-Solid Dosage Forms:

Creams/Ointments: For topical application (e.g., hydrocortisone cream).
Gels: Semi-solid systems (e.g., topical antibiotics).

Injectable Dosage Forms:

Solutions/Suspensions: For IV, IM, or SC administration (e.g., insulin injections).

Specialized Dosage Forms:

Inhalers: For respiratory conditions (e.g., albuterol inhaler).
Transdermal Patches: For sustained drug delivery (e.g., nicotine patches).
Suppositories: For rectal or vaginal administration (e.g., paracetamol suppositories).

Contents of Dosage Forms

Active Pharmaceutical Ingredient (API): The therapeutic component of the drug.
Excipients: Inactive ingredients that serve various purposes:
Binders: Hold the tablet together (e.g., cellulose).
Fillers: Add bulk to the dosage form (e.g., lactose).
Disintegrants: Help the tablet break down in the gastrointestinal tract (e.g., starch).
Preservatives: Prevent microbial growth (e.g., benzyl alcohol).
Flavoring Agents: Improve taste (e.g., in pediatric syrups).
Coloring Agents: Enhance appearance and patient acceptance.

Importance: Excipients ensure stability, bioavailability, and patient acceptability of the dosage form.

Why Are Dosage Forms Needed?

Stability: Protect the drug from degradation (e.g., light, moisture, temperature).
Controlled Release: Modify the rate and extent of drug absorption (e.g., extended-release tablets).
Patient Compliance: Make medications easier to take (e.g., flavored syrups for children).
Targeted Delivery: Deliver drugs to specific sites (e.g., inhalers for lungs, topical creams for skin).
Safety: Minimize side effects by controlling drug release (e.g., enteric-coated tablets to prevent stomach irritation).

Different Routes of Administration

Definition: The route of administration is the path by which a drug enters the body.

Enteral Routes (Through the Gastrointestinal Tract)

Oral (PO)

Most common; drugs are swallowed (e.g., Ibuprofen for pain relief).

Sublingual (SL)

Placed under the tongue for rapid absorption (e.g., Nitroglycerin for angina).

Buccal

Held between cheek and gums (e.g., Fentanyl buccal film for breakthrough pain).

Rectal (PR)

Suppositories or enemas for systemic or local effects (e.g., Diazepam rectal gel for seizures).

Parenteral Routes (Bypassing the GI Tract)

Intravenous (IV)

Directly into veins for immediate effect (e.g., Morphine for severe pain)

Intramuscular (IM)

Injected into muscles (e.g., Vaccines like Hepatitis B vaccine)

Subcutaneous (SC)

Injected under the skin (e.g., Insulin for diabetes)

Intradermal (ID)

Injected into the dermis (e.g., Tuberculin skin test for TB screening)

Intraosseous (IO)

Into bone marrow (emergency use, e.g., Epinephrine in cardiac arrest)

Topical Routes (Applied to Skin/Mucous Membranes)

Cutaneous

Applied to skin (e.g., Hydrocortisone cream for eczema)

Transdermal

Patches for slow systemic absorption (e.g., Nicotine patch for smoking cessation)

Ophthalmic

Eye drops/ointments (e.g., Timolol for glaucoma)

Otic

Ear drops (e.g., Ciprofloxacin otic for ear infections)

Nasal

Nasal sprays (e.g., Fluticasone for allergies)

Vaginal

Creams/suppositories (e.g., Clotrimazole for yeast infections)

Inhalation Routes (Through the Respiratory Tract)

Pulmonary (Inhalers/Nebulizers)

Delivered to lungs (e.g., Albuterol for asthma)

Nasal Inhalation

Systemic absorption via nasal mucosa (e.g., Nasal oxytocin for labor induction)

Other Specialized Routes

Intrathecal/Epidural

Into spinal canal (e.g., Bupivacaine for anesthesia)

Intra-articular

Into joints (e.g., Corticosteroids for arthritis)

Intraperitoneal

Into abdominal cavity (e.g., Chemotherapy for ovarian cancer)

Maximum quantities that can administered through various parenteral routes

1. Intradermal (ID)

Maximum Volume: 0.1 mL
Common Sites: Inner forearm, upper back

Purpose: Allergy testing, tuberculosis (TB) testing

2. Subcutaneous (SC or SQ)

Maximum Volume: 1.5 mL (generally 1 mL is preferred)
Common Sites: Upper arm, abdomen, thigh

Purpose: Insulin, heparin, vaccines

3. Intramuscular (IM)

Maximum Volume:

Deltoid muscle: 1 mL (up to 2 mL in adults)
Vastus lateralis (thigh): Up to 3 mL
Gluteus maximus (ventrogluteal, dorsogluteal): Up to 5 mL
Common Sites: Deltoid, vastus lateralis, ventrogluteal

Purpose: Vaccines, analgesics, hormonal therapies

4. Intravenous (IV)

Maximum Volume: Unlimited (dependent on patient tolerance and fluid balance)
Common Sites: Cephalic, basilic, median cubital veins

Purpose: Hydration, medications, blood transfusions, TPN

5. Intrathecal (IT)

Maximum Volume: Up to 4 mL (varies depending on drug and patient)
Common Sites: Subarachnoid space (lumbar region)

Purpose: Spinal anesthesia, chemotherapy

6. Intra-articular (IA)

Maximum Volume: 1–2 mL (small joints) to 5–10 mL (large joints)
Common Sites: Knee, shoulder, hip

Purpose: Corticosteroids, analgesics

7. Epidural

Maximum Volume: Typically 10–20 mL per dose (can be continuous infusion)
Common Sites: Lumbar or thoracic spine

Purpose: Pain management, anesthesia

Choice of needle size vs route of administration

The choice of needle size (gauge and length) depends on the route of administration, type of medication, and patient factors (such as age, weight, and muscle mass).

Intradermal (ID)

Needle Gauge: 25–27 G
Needle Length: 3/8–5/8 inch
Angle of Injection: 10–15°
Common Uses: TB test, allergy testing

Example Medication: Tuberculin PPD

Subcutaneous (SC/SQ)

Needle Gauge: 25–31 G
Needle Length: 3/8–5/8 inch
Angle of Injection: 45° (or 90° for insulin and heparin if using shorter needle)
Common Uses: Insulin, heparin, vaccines

Example Medications: Insulin, enoxaparin (Lovenox), MMR vaccine

Intramuscular (IM)

Needle Gauge: 20–25 G (oil-based solutions: 18–21 G)
Needle Length: Deltoid (arm): 1 inch
Vastus lateralis (thigh): 1–1.5 inches
Gluteal (buttocks): 1.5 inches
Angle of Injection: 90°
Common Uses: Vaccines, antibiotics, hormonal injections

Example Medications: Flu vaccine, testosterone, penicillin G

Intravenous (IV)

Needle Gauge: Peripheral IV: 18–24 G
Blood transfusions: 18–20 G
Chemotherapy/fragile veins: 22–24 G
Needle Length: 1–1.5 inches
Common Uses: Fluids, medications, blood products

Example Medications: Normal saline, morphine, vancomycin

Intrathecal (IT) & Epidural

Needle Gauge: 22–25 G (spinal needles may be thinner)
Needle Length: 3.5 inches or longer
Common Uses: Spinal anesthesia, chemotherapy

Example Medications: Bupivacaine, methotrexate

Intra-articular (IA)

Needle Gauge: 22–25 G
Needle Length: 1–2 inches
Common Uses: Joint injections

Example Medications: Corticosteroids, hyaluronic acid.

Medications Storage Requirements & Special Handling

Storage requirements are standardized environmental conditions (temperature, humidity, light exposure) necessary to maintain a drug’s chemical stability, potency, and shelf life until administration. These are dictated by manufacturers and regulatory bodies (FDA, USP).

Special handling refers to additional precautions or procedures required for certain medications due to their chemical instability, toxicity, bioavailability, or administration risks. These measures ensure the drug remains safe, effective, and uncontaminated during storage, preparation, and use.

Storage Requirements

Temperature control (e.g., refrigeration for insulin).
Humidity avoidance (e.g., dry place for levothyroxine).
Original packaging (e.g., blister packs for alprazolam).
Beyond-use dating (e.g., 28 days for opened insulin vials).

Example: Lantus insulin must be refrigerated at 2–8°C until first use, after which it can be stored at room temperature (≤25°C) for up to 28 days.

Special Handling

Protection from light, heat, or humidity (e.g., amber bottles for nitroprlycerin).
Sterility maintenance (e.g., IV chemotherapy drugs).
Hazardous drug protocols (e.g., PPE for methotrexate).
Avoiding physical stress (e.g., no shaking for NPH insulin).

Example: Nitroglycerin requires special handling due to its light sensitivity—it must be stored in amber glass bottles to prevent degradation into inactive compounds.

Why Proper Storage of Medications is Important?

Improper storage of medications can lead to serious risks, including loss of efficacy, toxicity, legal consequences, and patient harm. Below are the key consequences categorized by impact:

1. Loss of Potency & Reduced Effectiveness

Temperature Exposure:

Heat: Accelerates degradation (e.g., aspirin breaks down into salicylic acid, causing stomach irritation).
Freezing: Ruins protein-based drugs (e.g., insulin forms irreversible crystals).

Example: Vaccines stored outside 2–8°C may fail to induce immunity, leading to preventable diseases.

2. Toxicity & Harmful Byproducts

Chemical Breakdown:

Tetracyclines (expired or stored in heat) become nephrotoxic.
Nitroglycerin degrades into explosive compounds if exposed to light.

Example: Hydrogen peroxide decomposes into water if exposed to sunlight, losing antiseptic properties.

3. Microbial Contamination

Multidose Vials: If refrigerated but not labeled with beyond-use dates, they risk bacterial growth.

Example: Eye drops contaminated by improper storage can cause severe infections.

4. Financial Losses

Spoiled Medications:

Biologics (e.g., Humira) cost thousands per vial; improper storage wastes resources.
Insulin left unrefrigerated becomes unusable, increasing healthcare costs.

5. Legal & Regulatory Penalties

FDA/USP Violations:

Pharmacies can face fines for non-compliance with USP <795> (non-sterile) and <797> (sterile) guidelines.

Example: A pharmacy storing warfarin in a humid area could be liable if a patient experiences clotting issues.

6. Patient Harm & Medication Errors

Misidentification:

Look-alike drugs stored together (e.g., insulin U-100 vs. U-500) can cause dosing errors.

Example: Epinephrine auto-injectors exposed to heat may fail during anaphylaxis.

Mnemonic to remember critical storage rules

“C.R.Y.S.T.A.L.”

Controlled temperature
Refrigerate when needed
Yellow/amber bottles for light-sensitive drugs
Secure from humidity
Track expiration dates
Avoid freezing (unless specified)
Label opened vials with beyond-use dates

Consequences of Incorrect Storage for Different Medication Forms

1. Capsules

Moisture Exposure: Softens or dissolves gelatin shells, leading to premature release of active ingredients.
Heat: Causes sticking, melting, or brittleness (e.g., fish oil capsules leak when overheated).
Example: Doxycycline capsules degrade in humidity, reducing antibiotic efficacy.

2. Tablets

Humidity: Causes crumbling, discoloration, or microbial growth (e.g., aspirin smells like vinegar when hydrolyzed).
Heat: Accelerates chemical breakdown (e.g., nitroglycerin tablets lose potency if not stored in original airtight containers).

3. Injections (Parenteral Drugs)

Freezing: Ruins protein-based drugs (e.g., insulin forms irreversible crystals).
Heat Degradation: Vaccines (e.g., MMR) become ineffective if left at room temperature too long.
Light Exposure: Nitroprusside IV breaks down into toxic cyanide if exposed to light.

4. Suppositories

Heat Melting: Lose shape and dosage accuracy (e.g., paracetamol suppositories melt at >25°C).
Freezing: Alters texture, making insertion difficult.

5. Light-Sensitive Drugs

Photo-Degradation: Breaks down active ingredients (e.g., amiodarone turns brown and toxic in light).
Why Amber Containers?
- Blocks UV & visible light, preventing chemical reactions.
- Examples: Nitroglycerin, vitamin A, chlorpromazine.

6. Temperature-Sensitive Drugs

Cold Chain Drugs (2–8°C):

Example: Insulin, vaccines, biologics (e.g., Humira) lose potency if unrefrigerated.

Room-Temperature Drugs (15–25°C):

Example: Effervescent granules (e.g., Alka-Seltzer) absorb moisture and pre-activate.

7. Effervescent Granules/Tablets

Humidity: Causes premature reaction, making them fizz before use (e.g., vitamin C effervescent tablets clump).
Example: Potassium effervescent tablets become unstable if stored in bathrooms.

8. Eye Drops

Contamination: If stored improperly (e.g., opened >28 days), they grow bacteria (e.g., Pseudomonas).
Light/Temperature: Latanoprost (glaucoma drops) degrades in light, reducing efficacy.

9. Lab Compounds & Chemotherapy Drugs

Strict Cold Storage: Some monoclonal antibodies (e.g., Rituximab) require 2–8°C or they denature.
Light Sensitivity: Cisplatin (chemotherapy) degrades in UV light, reducing cancer-fighting effects.

Key Points

Amber bottles protect light-sensitive drugs.
Refrigeration (2–8°C) is critical for biologics, vaccines, and insulin.
Room-temperature storage must be cool, dry, and dark.
Effervescent drugs must stay airtight to avoid moisture.
Discard if storage conditions are violated (e.g., cloudy insulin).

Why Are Amber Bottles Used for Light-Sensitive Drugs?

Blocks UV Light: Prevents photochemical degradation (e.g., nitroglycerin, dopamine IV).
Maintains Stability: Amber glass/plastic is non-reactive compared to clear containers.

Why Cold & Dry Storage Matters

Cold (2–8°C): Slows chemical/enzymatic degradation (e.g., insulin, vaccines).
Dry Place: Prevents hydrolysis (e.g., penicillin tablets absorb moisture and break down).

How Temperature Affects Capsules

Condition	Effect on Capsules	Example
High Heat	Melts gelatin, leaks active drug	Fish oil capsules leaking oil
Humidity	Swells/sticks together	Probiotic capsules clumping
Freezing	Brittle shells, cracks	Some Rx capsules fragmenting

Common refrigerated medications (2–8°C or 36–46°F)

Insulin

Lantus (glargine)
NovoLog (aspart)
Humulin R (regular insulin)

Storage Rule:
Unopened: Refrigerate.
Opened: Can be kept at room temp (≤25°C/77°F) for 28 days (check manufacturer guidelines).

Vaccines

MMR (Measles, Mumps, Rubella)
HPV (Gardasil)
COVID-19 mRNA vaccines (Pfizer, Moderna)

Storage Rule: Most require 2–8°C; never freeze (except varicella vaccine, which is frozen).

Biologic Drugs

Humira (adalimumab) – Autoimmune diseases.
Enbrel (etanercept) – Rheumatoid arthritis.

Storage Rule: Keep refrigerated; some allow room temp for short periods (e.g., Humira for 14 days).

Antibiotic Suspensions (Liquids)

Amoxicillin-clavulanate (Augmentin)
Cefdinir (Omnicef)

Storage Rule: Refrigerate after reconstitution; discard after 7–10 days.

Eye Drops

Latanoprost (Xalatan) – Glaucoma.
Cyclosporine (Restasis) – Dry eyes.

Storage Rule: Some require refrigeration until opened (check label).

Certain Injectable Medications

Glucagon – Emergency hypoglycemia treatment.
Botox (onabotulinumtoxinA) – Cosmetic/therapeutic use.

Storage Rule: Refrigerate; Botox loses potency if frozen or heated.

Hormones

Gonadotropins (Follistim, Gonal-F) – Fertility drugs.
Octreotide (Sandostatin) – Acromegaly.

Storage Rule: Stable at 2–8°C; some tolerate room temp briefly.

Specialty Medications

DDAVP (desmopressin) – Diabetes insipidus.
Prostaglandins (dinoprostone) – Labor induction.

Storage Rule: Often heat-sensitive; strict refrigeration needed.

Duration of Drug Therapy

Duration of Drug Therapy is the length of time a patient should take a medication to achieve the desired therapeutic outcome.

Types:

- Acute Therapy: Short-term treatment (e.g., antibiotics for 7–10 days).
- Chronic Therapy: Long-term treatment (e.g., antihypertensives for life).
- Pulse Therapy: Intermittent dosing (e.g., corticosteroids for autoimmune conditions).
- Prophylactic Therapy: Prevention of diseases (e.g., vaccines, antimalarials).

Importance:

- Adherence to the prescribed duration is critical for effectiveness.
- Premature discontinuation can lead to treatment failure or resistance (e.g., antibiotics).