What is INN? Pharmacology Laboratory
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Here is a thorough explanation of INN in the context of a Pharmacology Laboratory course:
INN - International Nonproprietary Name
Definition
An International Nonproprietary Name (INN) is the official generic name given to an active pharmaceutical substance by the World Health Organization (WHO). It is a unique, globally recognized, publicly owned name - not belonging to any company - designed to identify a drug ingredient unambiguously across all countries and languages.
- Also called the generic name or nonproprietary name
- Contrasts with the brand/trade/proprietary name, which is owned and trademarked by the manufacturer
- WHO has a constitutional mandate to "develop, establish and promote international standards with respect to biological, pharmaceutical and similar products," of which the INN programme is a key part
Why Does INN Exist?
With tens of thousands of medicines on the market, the same drug substance can have dozens of different brand names in different countries and companies. The INN system provides one universally accepted name so that:
- Prescribers, pharmacists, patients, and regulators worldwide communicate without confusion
- Drug safety and pharmacovigilance reporting is standardized
- Pharmacopeias (official drug compendia), labeling, advertising, scientific literature, and drug regulation all use the same reference
INN vs. Other Drug Names
| Name Type | Who Assigns | Example |
|---|---|---|
| Chemical name (IUPAC) | Chemists, based on molecular structure | 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one |
| INN / Generic name | WHO (internationally) | diazepam |
| USAN (US Adopted Name) | US-specific body | diazepam (often same as INN) |
| Brand / Trade name | Manufacturer | Valium® |
As explained in Katzung's Basic and Clinical Pharmacology (16th ed.): "The brand name of a popular sedative is Valium. The generic (public nonproprietary) name of the same chemical substance adopted by United States Adopted Names (USAN) and approved by the FDA is diazepam."
INN Stems - A Key Pharmacology Tool
One of the most powerful aspects of the INN system is the use of stems (suffixes or prefixes) that indicate the pharmacological class of a drug. By knowing these stems, you can immediately identify the drug class from its INN alone:
| INN Stem | Drug Class | Example |
|---|---|---|
| -olol | Beta-blockers | propranolol, atenolol |
| -pril | ACE inhibitors | enapril, ramipril |
| -sartan | Angiotensin II receptor blockers | losartan, valsartan |
| -statin | HMG-CoA reductase inhibitors | simvastatin, atorvastatin |
| -cillin | Penicillin antibiotics | ampicillin, amoxycillin |
| -mab | Monoclonal antibodies | trastuzumab, bevacizumab |
| -nib | Tyrosine kinase inhibitors | imatinib, erlotinib |
| -prazole | Proton pump inhibitors | omeprazole, lansioprazole |
This makes INNs a diagnostic tool - you can deduce the mechanism of action, adverse effect profile, and drug interactions just from the name.
Importance of INN in Practice
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Prescribing - Either the brand name or the generic (nonproprietary) name may be written on a prescription. Prescribing by generic name offers flexibility and potential cost savings for the patient.
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Generic substitution - Generic drugs share the same INN as the originator brand and must meet equivalent bioavailability standards. In most countries, pharmacists can substitute a generic for a brand-name product if the INN is the same.
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Pharmacovigilance - Adverse drug reaction reports worldwide are classified by INN, enabling global signal detection.
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Drug regulation - Regulatory agencies (FDA, EMA, etc.) use INNs as the definitive identifier in approval processes.
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Scientific literature - Publications use INNs so findings are comparable across studies regardless of which brand was tested.
INN vs. USAN
- INN = assigned by WHO, internationally recognized
- USAN = US Adopted Name, assigned by the United States Adopted Names Council
- In most cases they are identical (e.g., both call the drug "diazepam")
- Occasionally they differ (e.g., paracetamol [INN] = acetaminophen [USAN])
Summary
The INN is the single, globally adopted generic name for a drug's active substance. It is public property, used in pharmacopeias, prescriptions, labeling, and scientific literature worldwide. Its systematic use of stems allows rapid identification of drug classes - making it an essential tool in pharmacology education and clinical practice.
Key reference: Katzung's Basic and Clinical Pharmacology, 16th Edition - WHO INN Programme (who.int/teams/health-product-and-policy-standards/inn)
What are excipients?
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Here is a thorough breakdown of excipients for your Pharmacology Laboratory course:
Excipients
Definition
The word excipient comes from the Latin excipere, meaning "to except" - literally meaning "everything other than" the active ingredient. Formally:
Pharmaceutical excipients are substances other than the active pharmaceutical ingredient (API) that are intentionally included in a drug delivery system, having been appropriately evaluated for safety.
They have no direct therapeutic action, but are absolutely necessary to make a drug product manufacturable, stable, deliverable, and acceptable to patients.
Why Are Excipients Needed?
A pure active drug substance alone cannot typically be administered to a patient. Excipients:
- Give the drug a physical form (tablet, capsule, liquid, cream, etc.)
- Control the rate and site of drug release
- Improve stability (shelf life)
- Make the product palatable and acceptable to patients
- Aid the manufacturing process
- Protect the drug from degradation
As noted in Lippincott Illustrated Reviews: Pharmacology: "Particle size, salt form, crystal polymorphism, enteric coatings, and the presence of excipients (such as binders and dispersing agents) can influence the ease of dissolution and, therefore, alter the rate of absorption."
Major Types of Excipients and Their Functions
| Excipient Type | Function | Common Examples |
|---|---|---|
| Fillers / Diluents | Bulk up the formulation to a workable size | Lactose, microcrystalline cellulose, starch |
| Binders | Hold tablet ingredients together during compression | Povidone (PVP), hydroxypropyl cellulose, gelatin |
| Disintegrants | Help tablets break apart after ingestion | Croscarmellose sodium, sodium starch glycolate |
| Lubricants | Prevent sticking to tablet press machinery | Magnesium stearate, talc, stearic acid |
| Glidants | Improve powder flow in manufacturing | Colloidal silicon dioxide |
| Coatings | Protect the tablet, mask taste, or control release | Hydroxypropyl methylcellulose (HPMC), cellulose acetate phthalate (enteric coating) |
| Preservatives | Prevent microbial growth in liquid/multi-dose preparations | Benzalkonium chloride, parabens, thiomersal |
| Solvents / Vehicles | Dissolve or suspend the API in liquid forms | Water, propylene glycol, ethanol |
| Surfactants / Emulsifiers | Stabilize emulsions; improve wetting and solubility | Polysorbate 80 (Tween 80), lecithin |
| Antioxidants | Prevent oxidative degradation of the drug | Ascorbic acid, sodium metabisulfite, BHT |
| Colourants / Dyes | Improve patient acceptance, aid identification, prevent counterfeiting | FD&C dyes, titanium dioxide |
| Flavours / Sweeteners | Mask unpleasant taste, especially in pediatric formulations | Saccharin, aspartame, cherry flavour |
| Buffers / pH adjusters | Maintain optimal pH for stability and bioavailability | Citric acid, sodium phosphate |
| Tonicity agents | Adjust osmolarity of injectable/ophthalmic preparations | Sodium chloride, mannitol |
Excipients and Drug Absorption
Excipients can significantly affect bioavailability. They are not always truly "inert" in a pharmacokinetic sense:
- Disintegrants and binders affect how fast a tablet dissolves and how quickly the drug becomes available for absorption
- Enteric coatings (e.g., cellulose acetate phthalate, which is insoluble in acid) delay drug release until the small intestine - used for acid-labile drugs (e.g., omeprazole) or drugs that irritate the stomach
- Excipients in transdermal patches (called "penetration enhancers") actively facilitate drug absorption through the skin - as noted in Goodman & Gilman's: "chemicals called excipients are used to facilitate the absorption of native testosterone across the skin in a controlled fashion"
Are Excipients Truly "Inert"?
Historically excipients were called inert, but this is not always true in practice. They can cause:
- Allergic/hypersensitivity reactions - Sensitivity to excipients (not the drug itself) can cause reactions ranging from mild rash to anaphylaxis. For example, drug contraindications routinely state "contraindicated in hypersensitivity to the active substance or any of its excipients"
- Interactions with the active drug - Some excipients can bind the API, reducing its bioavailability
- Interactions with other excipients - Incompatibilities can degrade the formulation
- Toxic effects in specific populations - e.g., benzyl alcohol (a preservative) causes "gasping syndrome" in neonates; lactose excipients can cause symptoms in lactose-intolerant patients; sorbitol (a sweetener) can cause osmotic diarrhea
Common excipient adverse reactions include:
- Colourants (e.g., tartrazine/FD&C Yellow No. 5) - urticaria, bronchoconstriction in susceptible individuals
- Preservatives (e.g., parabens, benzalkonium chloride) - contact dermatitis, bronchospasm
- Propylene glycol (solvent) - toxicity in large doses, especially in renal impairment
- Lactose - GI symptoms in lactose-intolerant patients
Excipients in Different Dosage Forms
- Tablets: fillers, binders, disintegrants, lubricants, coatings
- Capsules: gelatin shell (itself an excipient), fillers
- Injectables: solvents, buffers, tonicity agents, preservatives (for multi-dose vials)
- Topical creams/ointments: emulsifiers, preservatives, humectants
- Transdermal patches: adhesives, penetration enhancers
- Vaccines: adjuvants (e.g., aluminium salts), stabilizers, preservatives
Key Takeaway
Excipients are everything in a drug product except the active ingredient. While selected to be as inert as possible, they are pharmacologically relevant - they influence drug release, absorption, stability, and can cause adverse effects in susceptible patients. Different brands of the same drug (same API, same INN) may have different excipients, which can matter clinically.
References: Lippincott Illustrated Reviews: Pharmacology; Goodman & Gilman's The Pharmacological Basis of Therapeutics; Australian Prescriber - Pharmaceutical excipients
Identify the dosage form
Dosage Form Identification
The image shows Tablets — specifically a collection of tablets in various shapes, sizes, and colors.
What You Can See in the Image
| Feature | Description |
|---|---|
| Dosage form | Solid oral tablets |
| Colors present | White, blue, and brown/pink |
| Shapes present | Oval (oblong), round, and elliptical |
| Surface features | Several tablets have a score line (the groove running across the middle), which allows the tablet to be split into halves for dose adjustment |
About Tablets as a Dosage Form
Tablets are solid dosage forms containing one or more active pharmaceutical ingredients (APIs) compressed with excipients into a firm, discrete unit. They are the most widely used dosage form in medicine.
Types of Tablets Visible
Based on appearance, the tablets shown represent common subtypes:
- Uncoated (plain) tablets - the large white ones with visible score lines; compressed directly, no surface coating
- Film-coated tablets - the smooth blue and brown/pink ones with a uniform color coating; a thin polymer film covers the core to:
- Mask bitter taste
- Improve swallowing ease
- Protect from moisture/light
- Aid identification (color-coding)
- Control release in some cases
Scored Tablets
Several of the white tablets clearly show a score line (bisect groove). This is an intentional design feature that:
- Allows the tablet to be broken cleanly in half
- Permits flexible dosing (e.g., half a tablet for a lower dose)
- Is formed during the compression stage of manufacture
Key Tablet Components (Excipients)
| Excipient Role | Purpose in Tablets |
|---|---|
| Filler/Diluent | Provides bulk (e.g., lactose, microcrystalline cellulose) |
| Binder | Holds compressed particles together |
| Disintegrant | Helps the tablet break apart after swallowing |
| Lubricant | Prevents sticking to the punch/die during compression |
| Coating material | Film polymer (blue/brown tablets) for protection and identification |
Summary
The dosage form shown is oral tablets - a solid dosage form produced by compression. The image illustrates the variety in tablet shape (round, oval), size, and coating status (uncoated white tablets with score lines vs. film-coated blue and brown tablets), all of which are common design choices made to optimize patient use, drug stability, and dose flexibility.
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