Pharmacology of Aqueous Solutions

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Questions and Answers

What is the main purpose of a flavored syrup?

To serve primarily as a sweetener.

To act as a medicinal solution.

To be used as a vehicle or flavor for prescriptions. (correct)

To provide a high concentration of active ingredients.

Which preparation should be sipped slowly and not diluted?

Linctuses (correct)

Elixirs

Collodions

Flavored syrup

What is the primary component in collodions?

Pyroxylin. (correct)

Glycerin.

Sucrose.

Ethyl alcohol.

What type of preparation is typically used for skin massage?

Liniments Signup and view all the answers

Which of the following is true about tinctures?

They are alcoholic solutions of vegetable drug constituents. Signup and view all the answers

What distinguishes a medicated syrup from other types of syrups?

It includes added medicinal substances. Signup and view all the answers

Which of the following is NOT a component typically found in elixirs?

Pyroxylin Signup and view all the answers

What is the primary use of paints in pharmaceutical preparations?

For local application on skin or mucous membranes. Signup and view all the answers

What is the primary characteristic of spirits as defined in the content?

They include 50%-90% alcohol. Signup and view all the answers

Which type of dispersion involves components sized between 0.5 μm and 10 μm?

Fine dispersions Signup and view all the answers

What is an emulsion primarily composed of?

Two immiscible liquids with one dispersed. Signup and view all the answers

What is the role of emulsifying agents in emulsions?

To maintain the stability of the two-phase system. Signup and view all the answers

What is a major disadvantage of liquid dosage forms?

They can degrade more readily compared to solids. Signup and view all the answers

Fluidextracts are characterized by which of the following features?

They are liquid extracts containing alcohol as a solvent. Signup and view all the answers

Which type of colloidal dispersion is represented by butter and milk?

Colloidal dispersions Signup and view all the answers

What describes the therapeutic potency of fluidextracts compared to tinctures?

Fluidextracts are generally 10 times more concentrated than tinctures. Signup and view all the answers

What distinguishes pastes from ointments?

Pastes are stiffer and contain more solid materials than ointments. Signup and view all the answers

Which of the following dosage forms is specifically termed 'ophthalmic ointments'?

Ointments prepared for eye application. Signup and view all the answers

What characteristic of creams is highlighted compared to ointments?

They are more esthetically appealing and 'vanish' into the skin. Signup and view all the answers

Which component is NOT typically found in effervescent salts?

Large organic molecules. Signup and view all the answers

How are granules different from powders?

Granules are irregularly shaped agglomerates of smaller particles. Signup and view all the answers

What is the primary purpose of ointments?

To provide therapeutic or protective action when applied externally. Signup and view all the answers

What defines a gel's composition?

A dispersion of small inorganic or large organic molecules interpenetrated by a liquid. Signup and view all the answers

Which statement correctly describes tablets?

Tablets are solid dosage forms that may contain diluents, disintegrants, and other adjuncts. Signup and view all the answers

What is the primary advantage of intravenous bolus injection?

It allows for rapid distribution of the drug throughout the body. Signup and view all the answers

Which route of drug administration involves injecting the drug beneath the skin?

Subcutaneous Signup and view all the answers

What is a disadvantage of subcutaneous drug administration compared to intramuscular injection?

Less rapid absorption due to lower vascularity. Signup and view all the answers

In which method is the drug directly absorbed into the systemic circulation via the mucosal surfaces of the mouth?

Buccal and sublingual administration Signup and view all the answers

What is a characteristic of intrathecal injection?

It injects drugs into the spinal fluid. Signup and view all the answers

What is the typical purpose of intra-arterial injection?

To achieve high localized drug concentration in a specific tissue. Signup and view all the answers

Which administration route is most affected by first-pass metabolism?

Oral Signup and view all the answers

How does intravenous infusion maintain drug concentration in the body?

By achieving a constant input rate. Signup and view all the answers

Which route provides a rapid onset of action for lipid-soluble drugs?

Intramuscular Signup and view all the answers

What is a common disadvantage of oral drug administration?

First pass metabolism Signup and view all the answers

Which route of administration avoids gastric acid and first pass metabolism?

Sublingual Signup and view all the answers

What is a significant disadvantage of intravenous (i/v) drug administration?

Risk of sepsis or embolism Signup and view all the answers

Which route is often used for nocturnal administration of drugs?

Rectal Signup and view all the answers

What is a notable advantage of inhalational drug administration?

Suitable surface area of lungs Signup and view all the answers

What type of drug presentation has a delayed effect due to its formulation?

Enteric coated formulations Signup and view all the answers

Which route is characterized by the need for sterile preparation?

Intravenous Signup and view all the answers

Study Notes

Viscid Aqueous Solutions

Syrups are concentrated sugar solutions in water or other aqueous liquids.
- Simple syrup uses only purified water.
- Flavored syrups are non-medicated and contain aromatic substances for flavoring.
- Medicated syrups contain medicinal substances in addition to water.
Linctuses are viscous preparations for cough relief.
- They are typically solutions of active agents in a high concentration of sucrose, often with additional sweeteners.
- Linctuses should be sipped slowly and not diluted beforehand.
- The syrup content soothes the throat's mucous membranes.

Non-Aqueous Solutions

Collodions are liquid preparations containing pyroxylin (nitrocellulose) in a mixture of ethyl ether and ethanol.
- Applied to the skin with a brush, they leave a film of pyroxylin after evaporation.
- Example: Salicylic acid collodion is used as a keratolytic agent for treating corns and warts.
Liniments are liquids intended for massage into the skin.
- They often contain counter-irritants like methyl salicylate.
Paints are liquids applied to the skin or mucous membranes in small amounts with a brush.
- The solvent is usually alcohol, acetone, or ether, which evaporates quickly, leaving a film containing the active agent.
Elixirs are clear, sweetened, flavored hydroalcoholic liquids for oral use.
- Ethanol and water are the main ingredients, but they often contain glycerin, sorbitol, propylene glycol, flavoring agents, preservatives, and syrups.

Intermediate Products

Tinctures are alcoholic or hydroalcoholic solutions of chemicals or soluble constituents of vegetable drugs.
- They vary in concentration, with those derived from potent drugs typically being 10% strength.
- A 100 ml tincture contains the activity of 10 grams of the drug.
Spirits (also called essences) are alcoholic or hydroalcoholic solutions of volatile substances with 50%-90% alcohol content.
- The high alcohol content keeps water-insoluble volatile oils in solution.
- Examples include aromatic ammonia spirit (medicinal) and compound orange spirit and compound cardamom spirit (flavoring agents).
Fluidextracts are liquid extracts of vegetable drugs using alcohol as a solvent, preservative, or both.
- They are prepared by percolation, and each milliliter contains the therapeutic constituents of 1 gram of the standard drug.
- Fluidextracts of potent drugs are 10 times more concentrated than equivalent tinctures.

Dispersions

A dispersion is a mixture where one substance (dispersed phase) is uniformly distributed throughout another (dispersion medium or continuous phase).
- Both phases can be solid, liquid, or gas.
- Molecular dispersions have molecules evenly distributed (e.g., glucose in water).
- Colloidal dispersions have particles size between 1 and 100 nanometers (e.g., butter, milk).
- Fine dispersions have particles between 0.5 and 10 micrometers (e.g., magmas, gels, powder aerosols).
- Coarse dispersions have particles larger than 10 micrometers (e.g., suspensions, emulsions, foams, some aerosols).

Emulsions

Emulsions are thermodynamically unstable two-phase systems consisting of two immiscible liquids, one dispersed in the other as droplets.
- Droplet sizes range from 0.2 to 50 micrometers.
- They require a third substance called an emulsifying agent (emulgent) for stabilization.

Suspensions

Suspensions are preparations of finely divided drugs held in suspension within a suitable vehicle.
- Oral suspensions typically use an aqueous vehicle, while other suspensions may use different vehicles.

Advantages and Disadvantages of Liquid Dosage Forms

Advantages:
- More effective for some drugs like adsorbents and antacids.
- Useful for patients with difficulty swallowing solid dosage forms (e.g., children, elderly).
Disadvantages:
- Bulkier than solid dosage forms.
- Degrade more readily.
- More prone to interactions with other constituents compared to solid forms.

Semisolid Dosage Forms

Ointments are semisolid preparations containing a drug in a suitable semisolid base (hydrophilic or hydrophobic).
- Ophthalmic ointments are specifically prepared for application to the eye.
Creams are semisolid emulsions, generally less viscous and lighter than ointments.
- They are considered more aesthetically pleasing due to their non-greasy nature and ability to "vanish" into the skin upon rubbing.
Gels are semisolid systems consisting of a dispersion of small inorganic or large organic molecules interpenetrated by a liquid.
Pastes are intended for external application to the skin, similar to ointments.
- They contain more solid materials than ointments, making them stiffer and less penetrating.
- Primarily used for their ability to absorb discharges from skin lesions and provide protective action rather than therapeutic effects.

Solid Dosage Forms

Powders are mixtures of finely divided drugs and/or chemicals in dry form.
- This differentiates from a powder referring to a single substance's physical state.
Granules are agglomerates of smaller particles, irregular in shape, effectively behaving as single larger particles.
Effervescent salts are granules or coarse powders containing a medicinal agent with sodium bicarbonate, citric acid, and tartaric acid.
- When added to water, these ingredients react to release carbon dioxide, causing effervescence.
Tablets are solid dosage forms produced by compression or molding, containing medicinal substances with or without diluents, disintegrants, coatings, colorants, and other pharmaceutical adjuncts.

Routes of Drug Administration

Parenteral administration involves injecting drugs into the body:
- Intravenous bolus injection delivers the drug directly into the bloodstream for rapid distribution and action.
- Intravenous infusion administers the drug at a constant rate, maintaining a steady plasma drug concentration.
- Intramuscular injection injects the drug deep into a skeletal muscle, with absorption rate depending on factors like muscle vascularity, drug lipid solubility, and formulation.
- Subcutaneous injection delivers the drug beneath the skin, resulting in slower absorption than intramuscular injection due to lower tissue vascularity.
- Intradermal (intracutaneous) injection injects the drug into the vascular region of the skin beneath the epidermis.
- Intrathecal injection injects the drug into the spinal fluid.
- Intra-articular injection delivers the drug into the joint.
- Intra-arterial injection injects the drug into a specific artery to achieve high concentration in a particular tissue before systemic distribution. Used for diagnostic agents and occasionally for chemotherapy.
Enteral administration involves administering drugs through the gastrointestinal tract:
- Buccal and sublingual administration involves placing a tablet or lozenge under the tongue (sublingual) or against the cheek mucosa (buccal).
  - Non-polar, lipid-soluble drugs are absorbed through the epithelial lining of the mouth, entering the systemic circulation directly, bypassing the liver and any first-pass effect.
- Peroral (Oral) drug administration involves swallowing the drug, which then undergoes absorption from the gastrointestinal tract into the mesenteric circulation, hepatic portal vein, liver, and eventually systemic circulation.

Timeframes for Drug Absorption by Various Administration Routes

Minutes: Intramuscular (IM) and subcutaneous (SC injections), aerosols, gases.
Minutes to Hours: Short-term depot injections, solutions, suspensions, powders, granules, capsules, tablets, sustained-release tablets.
Several Hours: Enteric-coated formulations.
Days: Depot injections, implants.
Varies: Topical preparations.

Advantages and Disadvantages of Drug Administration Routes

Enternal (Oral):
- Advantages: Convenient, non-sterile, good absorption for most drugs.
- Disadvantages: Inactivation of some drugs by acid/enzymes, variable absorption, first-pass metabolism, gastrointestinal irritation.
Sublingual:
- Advantages: Bypasses the portal system and avoids first-pass metabolism; avoids gastric acid.
- Disadvantages: Infrequent route; limited sublingual preparations available.
Rectal:
- Advantages: Similar to sublingual, used for nocturnal administration of some drugs.
- Disadvantages: Infrequent route, variable absorption, aesthetically unacceptable.
Parenteral:
- Advantages: Rapid onset (emergency route), continuous infusion, complete availability, route for drugs causing local tissue damage.
- Disadvantages: Sterile preparation required, risk of sepsis or embolism, high drug levels at the heart.
Intravenous (i/v):
- Advantages: Same as parenteral.
- Disadvantages: Sterile preparation required, risk of sepsis or embolism, high drug levels at the heart.
Intramuscular (i/m):
- Advantages: Rapid onset for lipid-soluble drugs, depot injections for slow prolonged release.
- Disadvantages: Painful, tissue damage with some drugs, variable absorption.
Subcutaneous (s/c):
- Advantages: Same as i/m.
- Disadvantages: Same as i/m.
Inhalational:
- Advantages: Lungs offer a large surface area, ideal for volatile agents like anesthetic gases, aerosols, etc.
- Disadvantages: Few disadvantages.

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Description

Explore the fascinating world of viscous solutions such as syrups and linctuses. This quiz delves into the types, uses, and applications of both aqueous and non-aqueous solutions in pharmacology. Test your knowledge on the subject and enhance your understanding of these important formulations.