Tablet Types and Characteristics

Tablets: Types and Characteristics

• Conventional tablets are simple, uncoated or film-coated for rapid disintegration and absorption
• Effervescent tablets contain acid + carbonate/bicarbonate to dissolve before administration, allowing fast onset
• Enteric-coated tablets resist stomach acid and dissolve in the intestine to protect the drug from gastric acid or the stomach from irritant drugs
• Sustained/Controlled-Release tablets are designed for slow, prolonged release, extending the drug effect with fewer doses per day
• Chewable tablets are designed for chewing before swallowing, which is ideal for pediatric patients or those with difficulty swallowing
• Sublingual/Buccal tablets dissolve under the tongue or in the cheek pouch for rapid absorption into the bloodstream, which bypasses first-pass metabolism
• Orally Disintegrating Tablets (ODTs) disintegrate quickly in the mouth without water and are convenient for on-the-go use or for patients with dysphagia
• Lozenges/Troches dissolve slowly in the mouth for local effects in the oral cavity (e.g., sore throat relief)

Excipients in Tablets: Types and Functions

• Diluents/Fillers add bulk for appropriate tablet size; examples include Lactose and microcrystalline cellulose
• Binders help form a cohesive powder mixture; examples include starch paste and PVP (polyvinylpyrrolidone)
• Disintegrants promote the breakup of the tablet in the GI tract; examples include croscarmellose sodium and sodium starch glycolate
• Lubricants reduce friction during the manufacturing process which include magnesium stearate
• Glidants improve powder flow properties like colloidal silica
• Coating agents protect the tablet, mask the taste, and control release; examples include hydroxypropyl methylcellulose (HPMC) and shellac
• Colorants/Flavors enhance appearance and taste with agents like titanium dioxide and flavoring agents
• Preservatives prevent microbial growth in chewable or effervescent tablets using methylparaben and propylparaben

Oral Tablet Administration: Fate of Tablets

• Disintegration involves the tablet breaking apart into granules or powder in the stomach or intestine
• Dissolution involves the drug dissolving in gastrointestinal fluids
• Absorption involves the dissolved drug passing through the GI mucosa into the bloodstream
• First-pass metabolism involves some drugs being metabolized in the liver before reaching systemic circulation
• Distribution involves the drug being transported to tissues and the site of action
• Elimination involves the drug being excreted via the kidneys, bile, or other pathways

Tablets: Quality Requirements

• Uniformity of Weight ensures consistent dosing
• Content Uniformity ensures each tablet contains the intended amount of active ingredient
• Disintegration Time should meet pharmacopeial standards for specific tablet types
• Dissolution Profile ensures the drug is released at an appropriate rate
• Hardness/Friability means the tablet must be strong enough to withstand handling but not too hard to disintegrate
• Stability should maintain efficacy, safety, and quality over shelf life
• Microbial Limits are especially important for chewable or effervescent tablets

Special Tablet Types and Administration Tips

• Enteric-Coated tablets should be swallowed whole, and not crushed or chewed
• Sublingual/Buccal tablets should not be swallowed but allowed to dissolve in the mouth
• Orally Disintegrating tablets should be placed on the tongue and allowed to dissolve without water
• Effervescent tablets should be dissolved in a full glass of water before drinking
• Modified/Sustained-Release tablets should be swallowed whole to avoid breaking, crushing, or chewing, unless otherwise specified
• Chewable tablets should be chewed thoroughly before swallowing

Pharmaceutical Principles of Tablets in Pharmacy Practice

• Patient Counseling: need to ensure proper instruction on administration, especially avoiding crushing enteric-coated tablets
• Therapeutic Substitution: understand tablet release types when substituting generics or brands
• Storage Advice: protect from moisture and heat, which is especially important for effervescent and ODTs
• Compliance Monitoring: use patient-appropriate formulations, like chewable tablets for children
• Medication Review: check for drug-food interactions, and avoid antacids with enteric-coated drugs
• Compounding & Dispensing: understand tablet properties when splitting or re-packaging

Tablet Identification Features

• Shape and Size: these are unique for different drugs
• Color: helps distinguish between medications
• Embossing/Engraving: brand names, logos, or numbers
• Scoring: allows splitting for dose adjustments
• Coating: this may be clear or colored, indicating a specific release mechanism

Tablet Excipients: Types and Roles

• Diluents/Fillers increase bulk; lactose and MCC are examples
• Binders hold particles together; PVP and starch paste are examples
• Disintegrants facilitate tablet breakup; croscarmellose sodium is an example
• Lubricants reduce friction in manufacturing using magnesium stearate
• Glidants improve powder flow using colloidal silica
• Coating Agents protect and control release using HPMC and shellac
• Colorants/Flavors enhance appearance/taste using titanium dioxide
• Preservatives prevent microbial growth using parabens

Compounding Tablets into Liquid Dosage Forms

• Tablets can be compounded into solutions if the drug is fully soluble
• Tablets can be compounded into suspensions if the drug is poorly soluble

Compounding Process for Tablets

• Crush the tablets into a fine powder
• When making a solution, dissolve the drug in a suitable solvent (e.g., water, alcohol, glycerin)
• When making a suspension, mix the powder with a vehicle (e.g., syrup, ora-sweet, ora-plus)
• Add necessary stabilizers, preservatives, sweeteners, and flavoring agents
• Adjust pH and viscosity, if needed

Compounding: Tablet Type

• Immediate-release tablets are preferred because modified-release formulations may alter drug release unpredictably

Oral Tablet Administration: Processes Before Drug Absorption

• Disintegration: a tablet breaks into granules
• Dissolution: the drug dissolves in GI fluids
• Absorption: the drug crosses Gl membrane into blood

Administration Instructions for Tablets

• Take with sufficient water to aid dissolution
• Avoid crushing enteric-coated or sustained-release tablets
• Follow food interaction guidelines, as some drugs are better absorbed with food while others are better absorbed on an empty stomach

Interactions: Co-Administered Drugs and Liquids

• Antacids may alter stomach pH, which affects drug dissolution
• Grapefruit juice can affect drug metabolism
• Milk/calcium-containing foods may bind certain drugs (e.g., tetracyclines)
• Enzyme inhibitors/inducers (e.g., CYP450 inducers like rifampin) can increase or decrease drug bioavailability

Film-Coating: Reasons and Effects on Release

• Protection: film-coating shields from moisture, oxidation, and stomach acid
• Taste Masking: film-coating improves palatability
• Modified Release: film-coating controls drug release (e.g., enteric coatings dissolve only in the intestines)
• Appearance: film-coating enhances identification

Coating Polymers: Dissolving Properties and Release Patterns

• Water-soluble coatings lead to immediate release
• pH-sensitive coatings lead to delayed/enteric release
• Hydrophobic coatings lead to extended-release

Film-Coated Tablets: Considerations for Administration

• The coating should be not be crushed or chewed if it is for protection or release modification
• An alternative formulation should be used if a patient has swallowing difficulty rather than breaking the tablet
• Tablets can be taken with or without food, unless otherwise specified

Tablets: Coated Particulates

• Particulate-coated tablets may allow modified release if split, while film-coated tablets often lose their function when broken

Capsules: Types and pH Considerations

• Gelatin dissolves rapidly in water at pH >4 and warm temperatures (>30°C)
• Acidic environments (pH 3) promote swelling, but excessive cross-linking from aldehydes may reduce solubility
• Alkaline pH (>7) may weaken the gelatin structure, slowing dissolution

Hard-Shell Capsules

• Two-piece and solid-filled that dissolve in acidic gastric fluid (pH 1-3) unless enteric-coated

Soft-Shell Capsules (Softgels)

• One-piece and liquid-filled that typically dissolve in the stomach (pH 1-3), but some use enteric coatings to delay release until pH 5.5+

Capsule Shell Stability and Solubility

• Regular gelatin - soluble in water and dissolves fast in gastric fluid (pH 1-3) and used in most IR capsules
• pH-sensitive enteric coating - insoluble at pH <5, and dissolves in intestinal pH (5.5-7.5) which protects acid-sensitive drugs or prevents gastric irritation
• Cross-linked gelatin - reduced solubility in strongly acidic (pH 3) or alkaline (pH >7) which can result from improper storage or aldehyde exposure

pH Considerations

• May cause premature shell softening in gelatin capsules
• Alkaline Fillers can slow gelatin shell dissolution
• Hydrophilic Solvents may increase water uptake, altering capsule dissolution rate
• Lipophilic Solvents can reduce interaction with water, potentially delaying dissolution

Softgel Formulations

• Enteric-coated softgels dissolve at pH 5.5-6.8 in the small intestine
• Self-emulsifying drug delivery systems (SEDDS) may use pH changes to improve solubility (e.g., Sandimmune®)

Drug Absorption

• Lipofen (fenofibrate) is better absorbed in high-fat meals, which increases bile secretion to aid dissolution
• Prometrium (progesterone) has increased bioavailability with food, and the food delays gastric emptying which allows better dissolution
• Ciprofloxacin & Levofloxacin chelation with metal ions (Mg, Ca, Fe, Zn) reduces absorption

Capsule Mixing

• Gastric acid (pH 1-3) can degrade some drugs, requiring enteric coatings
• Alkaline pH in intestines (5.5-7.5) is ideal for many poorly soluble drugs

Water Insoluble

• Slowly permeable to water and does not dissolve causing an extended release

pH-Sensitive capsule contents

• Proton pump inhibitors (PPIs) should not be mixed with acidic foods, as they require enteric coatings to reach pH >5.5
• Weakly basic drugs (e.g., dipyridamole) dissolve better in acidic pH

Modified Release Products: Definitions & Release Patterns

• Immediate-release drugs are rapidly released after administration with no extended effect
• Modified-release drugs have a non-conventional release profile based on time/location, which includes delayed & extended releases
• Delayed-release drugs release begins after a delay, typically in the intestine (pH-dependent)
• Extended-release drugs are released slowly over time for a prolonged therapeutic effect, often zero-order

Modified-Release Forms: Purpose

• Delayed-release forms protect drugs from stomach acid or reduce gastric irritation
• Extended-release forms reduce dosing frequency, maintain steady plasma concentration, and improve patient adherence

Film-Coating

• Administer by swallowing whole, do not crush or chew. Modified-Release Systems

The Osmotic Pump Mechanism

• A semi-permeable membrane along with an osmotic core forces fluid in which increases pressure and the drug being expelled via a laser-drilled hole.
• The process is independent of pH and GI motility.
• Administer by swallowing whole with water, the tablet remains intact in the stool.

Ion-Exchange Resin

• Administer is often in liquid or chewable form
• Drugs are bound to an insoluble cation/anion-exchange resin that exchanges with GI ions to sustain release. An example is Karbinal ER, or Dyanavel XR.

Hydrophilic Polymer Matrix

• Drug is dispersed in a swelling/eroding gel matrix (e.g., HPMC) and water forms a gel layer that controls diffusion and erosion.
• Administer by not chewing or crushing (e.g., Depakote ER)

Combining IR + ER Granules

• Immediate release allows for a fast onset of action (loading dose)
• Administer by combining into a single dosage form (e.g., capsules with mixed beads) Extended-release provides a prolonged effect

Opthalmic Products: Features

• Aseptic technique: Use a cleanroom/laminar hood
• Sterile components: Use sterile water, filtered solutions
• pH/Tonicity adjustment: Use Buffers and tonicity agents
• Preservatives: Required for multi-dose containers
• Final Filtration: Use a 0.22 µm filter for required testing

Requirements: Opthalmic Products

• Test pH
• Sterility -Particulate matter
• Endotoxin testing not required for topicals

Packaging and Administration: Opthalmic Products

• Test pH
• Wash hands and only put one drop per eye
• Avoid blending or touching the eye
• Press on the inner corner of the eye
• Apply a thin ribbon 1/2 inch in lower lid
• Close eyes and rotate to distribute