What is solid:

Define a Solid

A material that retains its shape unless a compression force is applied and is made up of molecules held together by intermolecular forces.

what are Polymorphs

Compounds that can exist in different crystalline structures, influencing properties like melting point, solubility, and bioavailability.

what Crystalline compounds

Compounds with a repeating structure forming a crystal lattice, with methods like evaporative, cooling, and precipitation crystallization.

explain evaporative crystallisation

a process in which a solution is concentrated by evaporating the solvent, leading to the precipitation of the solute as crystals.

This technique is commonly used in various industries for the production of high-purity crystals or for separating and purifying substances from solutions.

explain cooling evaporation

process in which a solution is cooled to induce the crystallization of a solute. This method is commonly used to produce solid crystals from a solution by reducing the temperature, which decreases the solubility of the solute and promotes its precipitation in a crystalline form.

Cooling crystallization is widely employed in various industries for the production of high-purity crystals, purification of substances, and isolation of specific compounds.

explain precipitation crystallisation

process in which a solute is brought out of a solution to form solid crystals. This occurs when the solubility of the solute in the solvent is exceeded due to changes in conditions such as temperature, pressure, or the addition of a second solvent.

what is crystallisation controlled by

• Supersaturation state

• Nucleation after seeding

• Rate of cooling

what is a Crystalline habit

Describes the shape of drug crystals, influenced by factors like solvent, impurities, additives, and physical conditions.

what influences crystallisation habitat

• Solvent

• Impurities

• Additives

• Physical conditions

Solvates

Orderly arrangements of drug molecules with solvent molecules, affecting solubility and stability compared to anhydrous forms.

what are hydrates

are solvents where crystallisation solvent is water

Co-crystals

Combinations of an active drug and another molecule forming stable structures with lower melting points and increased solubility.

what is a benefit of co-crystals compared to polymorphs

more stable than polymorphs of drug reducing concerns about polymorph instability in final dosage form

Hygroscopicity and deliquescence

Hygroscopic powders absorb water from the atmosphere, while deliquescent powders form a solution by absorbing water vapor.

what does Melting point measure

Measures the strength of interactions between molecules

do crystalline or amorphous forms have higher melting points

crystalline

describe Amorphous solids

Lack a sharp melting point, have no orderly arrangement of molecules, and are generally porous with lower density.

how may amorphous forms be formed

 formed when a drug solution is cooled rapidly that solute molecules lose mobility before assuming their lattice  position

Drug salts

Prepared from reactions of weak base drugs with strong acids or weak acid drugs with strong bases, affecting properties like solubility and stability.

advantages of drug salt formulation

• Enhanced solubility

• increase dissolution rate

• higher melting point

• better taste

• higher bioavailability

• better processability

• easier synthesis or purification

• potential for controlled release

disadvantages of drug salt formulation

• decreases percentage active ingredient

• decreased chemical stability

• increased number of polymorphs

• reduced dissolution in gastric media

• no change in solubility in buffers

• corrosiveness

• possible disproportionation

• additional manufacturing step

• increased toxicity