Thursday, July 9, 2020

Advantages and disadvantages of sustained release dosage form

Oral drug delivery has been known as the most commonly used route for the systemic delivery of drugs through various pharmaceutical products. The sustained release dosage forms are intended to release medicaments at a predetermined rate so that a constant concentration of medicaments can be maintained for a specific period. A sustained release dosage form is designed to achieve prolonged therapeutic effects of the drug in the bloodstream. It releases the medicine at a prescribed rate, according to the needs of the body throughout the treatment period.
Advantages of sustained release dosage forms:
  • The major advantage of the sustained release dosage form is that it provides long-term therapeutic effects by continuously releasing the drug.
  • It provides prolonged action of the medicaments and reduces the frequent dosing.
  • Control of drug therapy can be achieved by using a sustained release dosage form.
  • The extent and rate of drug absorption can be modified by using a sustained release dosage form.
  • Patient compliance is another major benefit of a sustained release dosage form.
  • It does not need special storage conditions and is easy to handle or transport.
  • The unpleasant odor and taste of active pharmaceutical ingredients may be masked by coating or by making granules.
  • These types of dosage forms are also stable in physical, chemical, and microbiological properties.
  • This system has the benefit of a single dose for the entire duration of treatment and delivers the API directly to the specific site.
  • It reduces the local side effects, by reducing the total amount of the drug.
  • Different drugs and excipients or ingredients can be mixed to make it convenient for the patient to reduce the administration of multiple doses.
Disadvantages of sustained release dosage forms:
  • The major disadvantage of the sustained release dosage form is that, in traditional solid dosage forms, the dose can be adjusted by dividing the tablet into two parts. This is not possible in a sustained release dosage form as the release property may be lost if the dosage form is broken or crushed.
  • Side effects can remain much longer as it releases the medication for longer.
  • Children and the elderly are hesitating to swallow and cannot be given to an unconscious patient.
  • This has less flexibility in dose adjustment.
  • The rate of release may change by various factors
  • This is expensive compared to other solid dosage forms because its formulation and manufacturing process is expensive.
  • The time required for the absorption of the released drug may vary from one dose to another.
Commonly asked questions on dosage forms are as follows.
 
What are the types of modified release dosage forms?
Extended-release dosage form and delayed-release dosage form are two types of modified release dosage forms. Controlled release, sustained-release, and prolonged-release are the different terminologies also used in the modified release. Generally, tablets, capsules, and, carpets are used for this formulation.
 
What is the major disadvantage of effervescent tablets?
The major disadvantage of effervescent tablets is that they use a complex, expensive manufacturing process and excipients.
 
What is the advantage of using modified release dosage forms?
The modified release dosage forms are designed to ensure that the concentration of active pharmaceutical ingredient (API) is maintained at suitable time intervals, deliver the medication to that part of the body, and simplifying the dosing schedule.
 
What is the disadvantage of the enteric coating?
The major disadvantage of enteric coating is that enteric-coated tablet taking a long coating time and high bulk resulting in a costly product.
 
What is the advantage of sublingual or buccal administration?
Sublingual or buccal administration of the drug provides rapid onset of action which is required for the treatment of acute disorders.
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Wednesday, July 8, 2020

Advantages and disadvantages of extended release dosage forms

The extended-release dosage form is designed to deliver medicaments to the body where it should be absorbed, simplifying the scheduled dosing and ensuring that the drug concentration is maintained at a suitable time interval. Extended-release dosages are a commonly used technique for delivering drugs into the bloodstream and are achieved by incorporating coated granules or beads into capsules or tablets. Sustained-release, controlled-release, and long-acting drug products are some examples of extended-release dosage forms. There are some advantages to providing drugs administered by this process, but it also has some disadvantages, let’s check it.
Advantages of extended-release dosage forms:
  • The major advantage of the extended-release dosage form is that it provides long action of the drug and reduces the frequency of dosing.
  • The extended-release dosage forms often reduce the requirement of night-time doses that are helpful to both caregiver and patient.
  • There is no need to take tablets and capsules repeatedly, which is very beneficial for children and old people.
  • It can be used to maintain drug levels by controlling the rate of drug release.
  • Extended-release dosage forms may improve patient compliance.
  • The rate and extent of absorption of medicaments can be modified.
  • There is no problem with the unpleasant taste and odor of the drugs as it is already coated with granules.
  • It reduces side effects, reduces the amount of time required for health treatment, and improves medical benefits.
  • They are easy to carry, transport, and don't require special storage conditions.
  • Formulation of extended-release can be possible in solid dosage forms but is very difficult to formulate in liquid and semi-solid dosage forms.
  • It delivers the medicaments at the prescribed rate as per the needs of the body throughout the treatment of the patient.
Disadvantages of extended-release dosage forms:
  • The major disadvantage of the extended-release dosage form is its high cost as it has a higher manufacturing cost than other dosage forms.
  • Another major disadvantage of extended-release dosage forms is that side effects can remain much longer than an immediate release, short-acting product.
  • Failure of the technique may result in the risk of the sudden and total release of the drug.
  • It is not useful whenever partial doses are needed because they need to be taken intact, not divide into parts.
  • Splitting or divided into parts can cause its release property to be lost.
  • The combination of multiple drugs and excipients or ingredients complicates it to formulate.
  • Extended-release formulations may cause a slower onset of action.
  • Not all drugs are compatible with the formulation of extended-release dosage forms.
  • The release rate can change by various factors such as food and fasting.
  • The release rate can vary from one dose to another dose.

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Tuesday, July 7, 2020

Advantages and disadvantages of semisolid dosage forms

Semisolid dosage forms are neither solid nor liquid, however, they are a combination or mixture of both, and they used for both local and systemic effects. Pharmaceutical semisolid dosage forms such as creams, ointments, gels, suppositories, and paste are used for topical application. Semisolid dosage forms are intended used as drug carriers that are transported topically through the skin, buckle tissue, rectal tissue, outer ear lining nasal mucosa, urethral membrane, vagina, and cornea. The semisolid may adhere adequately before washing on the surface of the application; this helps to extend the supply of drugs on the application site.
Advantages of semi-solid dosage forms:
  • The major advantage of a semi-solid dosage form is that it can be applied directly to the affected area, it gives prolong the action, and does not need to be administered orally.
  • It is convenient for unconscious patients or patients, such as children and old people, for whom oral administration is difficult.
  • Semisolid dosage forms are more stable in atmospheric conditions than liquid dosage forms and solid dosage forms.
  • It is suitable for those APIs that are low-density, amorphous hygroscopic.
  • Different drugs and excipients or ingredients can be added together to form a single dose.
  • It gives better adhesion and lasts long after application, hence the medicament give longer action.
  • It is washable after each use.
  • It is used externally, thereby reducing the risk of side effects.
  • It does not harm the gastrointestinal tract, as it does not need to be taken orally.
  • The semi-solid dosage form is more convenient for patients than other forms of drug administration.
  • It is suitable for medicines with a bitter taste, as it does not need to be taken orally.
Disadvantages of semi-solid dosage forms:
  • The major disadvantage of the semi-solid dosage form is that it has no dose accuracy and it needs to be applied directly.
  • In general, Pharmaceutical creams, ointments, gels, suppositories, and paste are greasy and they difficult to clean.
  • The semi-solid dosage form is less stable than the solid dosage form.
  • The base used in the dose may be oxidized.
  • The need to apply with the fingers every time can cause contamination.
  • Some patients may become irritation or allergic.
  • Semisolid dosage forms are usually a costly dosage because its manufacturing process is complex.
  • Semisolid dosage forms are Physio-chemically less stable compared with the solid dosage form.
  • Clothing staining is often associated with the use of creams, ointments, gels, and paste.

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Monday, July 6, 2020

Advantages and disadvantages of solid dosage form

Dosage forms come in many types, depending on the method or route of administration. Solid dosage forms, semi-solid dosage forms, liquid dosage forms, and gaseous dosage forms are used for the diagnosis or treatment of the disease by various routes. Solid dosage forms are the most significant dosage forms in pharmaceuticals; it has one or more unit dose of medicament. The solid dosage form is the most commonly used and prescribed by doctors as compared to other dosage forms. It can be administered orally in the form of tablets, capsules, powders, etc. Of these, the tablet is one of the most commonly used oral solid dosage forms.
Solid dosage forms (Tablet or capsule)

 Advantages of solid dosage form:
  • The major advantage of solid dosage forms is a high precision, lowest variability, stable and accurate dosing.
  • The formulation of solid dosage forms is simpler than liquid and semi-solid dosage forms.
  • Solid dosage forms have a strong onset of action.
  • Several medicines and excipients or ingredients can combine, making it easier for the patient to avoid having to administer multiple doses.
  • The liquid form of the drug can be converted into a solid form using a capsule.
  • Doses are available according to the patient's requirements.
  • These are easy for packaging, transport and it does not require special conditions for storage.
  • It is easy to swallow and can be attractive to children.
  • It is very simple to swallow with water.
  • It is useful whenever partial doses are required. It is easy to divide it into parts.
  • As it is easy and rapidly digested it does not harm the gastrointestinal tract.
  • Unpleasant taste and odor of drugs can be masked using the capsules and sugar coating for tablets.
  • It can be manufactured in custom sizes, shapes, and colors as per requirement.
  • It can protect the API from atmospheric conditions such as moisture, temperature, and light, etc.
  • Solid dosage forms are stable in chemical, physical, and microbiological properties.
Disadvantages of solid dosage form:
  • The main disadvantage of the solid dosage form is that it is not easy to swallow, particularly for children, and the elderly, and it cannot be given to the unconscious patient.
  • An API that has slow dissolution rates, low solubility in water, low density, amorphous and high absorption in the gastrointestinal tract, they are difficult to prepare.
  • Several medicines cause gastric irritation when administered in the form of a tablet.
  • Hygroscopic drugs are not suitable for these types of dosage forms.
  • Sometimes patients experience discomfort due to unpleasant taste and smell and avoid swallowing it.
  • Coating, encapsulation of tablets, and complex process of capsules may increase production costs in the pharmaceutical industry.
  • Some examples of solid dosage forms are as follows.
  • Chewable tablets, buccal tablets, film-coated, enteric-coated tablets, sublingual tablets, and effervescent tablets, hard-shelled capsules, soft gelatin capsules, enteric-coated capsule, HPMC capsule, pills pastilles, lozenges, troches, powders, suppositories, and pellets, etc.


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Sunday, July 5, 2020

Advantages and disadvantages of liquid dosage form

Liquid dosage forms are effective pharmaceutical products containing a mixture of active pharmaceutical ingredients (API/Drug) and non drug components (excipients). It is a dose of a drug used as a medicine for consumption or administration. Many liquid dosage forms are used in the pharmacy, but the most commonly used are syrup, suspension, and elixirs. The general category of liquid oral doses includes a broad range of dosage forms, broadly classified as monophasic and biphasic. Whereas dosage forms in both types comprise at least one drug, monophasic forms are homogeneous and completely dissolve in liquid, whereas biphasic forms in a vehicle do not dissolve.
Advantages of liquid dosage form:
  • The major advantage of the liquid dosage method is that it is better for patients who have difficulty swallowing solid medicines because it is easier to swallow than solid dosage forms.
  • Liquid dosage forms have faster absorption than solid dosage forms.
  • It is suitable for use patients with infants, geriatric, and mental health problems.
  • Doses may vary from per tablespoon to milliliter, which is difficult in solid dosage forms.
  • Liquid dosage forms are absorbed faster than solid dosage forms because APIs are already dissolved.
  • This may provide greater flexibility in achieving the appropriate dose of the drug.
  • It can be designed for any route of administration.
  • It is the best choice for children and old people.
  • This can be attractive by container and color.
  • Flavors (sweetening agents/sugar) can be added to mask the bitter or unpleasant taste and odor.
Disadvantages of liquid dosage form:
  • The major disadvantage of the liquid dosage form is that, is less stable than other doses and has a shorter shelf life which is due to the nature of being in a liquid.
  • The liquid dosage form is more susceptible to bacterial microorganisms than tablets and capsules.
  • Some drugs are poorly soluble hence difficult to formulate.
  • It is bulky so it is difficult to handle, transport and store.
  • It requires special storage conditions because it is less stable.
  • Its manufacturing process is complex, so the production cost is high.
  • It is easily affected by temperature, light, and microorganisms.
  • Each time of dose needs to be measured, so the accuracy of the dose may vary each time.
  • A loss can occur as the container breaks and falls.
  • Difficult to mask the unpleasant taste or odor compared to tablets and capsules.

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Saturday, July 4, 2020

Advantages and disadvantages of tablet dosage form

Oral dosage forms are generally the most suitable option among different choices. Since medicine via the oral route is one of the best choices for taking. It is a convenient and simple way for any patient (adult, children’s) to take medicine. For several advantages, medicines taken orally are much preferred than other routes.
Tablets and capsules are the most commonly prescribed oral dosage forms by doctors. The tablet is an oral solid dosage form containing a mixture of active pharmaceutical ingredients (API) with or without excipients; it is prepared by either compressed or molded. Of all medicines, the tablet is the most commonly prescribed by doctors because of its many advantages.
Advantages of tablets dosage form:
  • The major advantage of the tablet is that all medicines are available in the form of a tablet, only except where the preparation or administration is difficult.
  • Whenever a partial dose of a drug is required, it can be cut or crush into parts is easy, which is not possible in capsules.
  • No dose measurement is required.
  • The tablets are convenient to use and elegant.
  • They can be attractive by making them different in colors.
  • Compared to other dosage forms, the tablets are inexpensive and are economical for manufacturing, packing, handling, transportation, and storage.
  • Tablets are generally an inexpensive dose, as its manufacturing process is not complex.
  • Tablets can be formulated to reduce the use of multiple tablets; by mixing multiple drugs of different doses into a tablet.
  • The tablet gives a precise dose of medicament to the patient.
  • It can be coated with sweetening agents to mask the taste and odor of bitter drugs and ingredients.
  • A wide range of tablet types can available such as variations in color, size, shape, and dosage.
  • The tablet can be formulated as a fast release of drugs or as a controlled release of drugs.
  • The tablet is more stable as compared with other dosage forms since it provides prolonged stability to the medicament.
  The disadvantage of tablet dosage form:
  • Atmospheric conditions, such as light, wind, etc. can damage the quality of the tablet; it required to be sealed to protect it.
  • The tablet cannot manufacture with a mixture of different drugs due to the incompatibility of the drugs, which is possible in a capsule by making granules.
  • Several drugs resist compression in a dense compact due to the low-density character or amorphous nature, therefore preparing this kind of tablet is complicated.
  • Those API has poor properties of wetting and slow dissolution, they can be complex or not possible to formulate and manufacturer in the form of a tablet.
  • To mask the taste and smell of bitter drugs and ingredients, it needs to be coated with sweetening agents, this increases production costs.
  • The tablets are unsuitable for children and old people because they can't easily take it.
  • It is also not suitable for patients with vomiting and diarrhea.
  • Many medicinal products cause gastric pain when administered in the form of a tablet.

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Saturday, June 27, 2020

Advantages of capsules over tablets

Capsules are most commonly prescribed as an oral solid dosage form, which is made of special film-forming material, used to enclose drugs and excipients to a relatively stable shell from which they can be taken orally. There are two major types of capsules are soft-shell capsules and hard-shelled capsules. Tablets are the most commonly used oral solid dosage forms in which the powdered drug that has been mixed with excipients and then compressed them to get the shape. Tablets can be coated to protect from taste and odor, generally, it comes with uncoated.
Advantages of capsules over tablets

The most commonly used forms for the medication in the finished product are tablets and capsules. Some drugs can be used in liquid oral dosage forms, but tablets and capsules are the most common. Both are working for a specific purpose of delivering a drug or supplement through your digestive tract. Both tablets and capsules offer numerous advantages. Capsules are convenient for consumers for a few different reasons; let's look at some advantages of capsules over tablets.
  • The major advantage of the capsule over the tablet is that within the capsule the most numerous drugs and excipients or ingredients are mixed, making it easier for a patient to swallow the capsule without having to deal with an unpleasant taste or odor.
  • Compared to tablets, it is less likely to cause gastrointestinal irritation.
  • The capsule is quite convenient for the patient as it is easier to swallow than a tablet.
  • The capsule is tamper-resistant- it is not easy to split it in half or crush it like pills, so it may be more likely to be taken as needed.
  • It can be attractive to children as it is available in a wide range of colors.
  • The gelatin shell can provide protect the drug from moisture, light, and air.
  • The capsules have higher bio-availability compared to tablets, which means more drugs are likely to enter your bloodstream.
  • It can dissolve rapidly, reach the bloodstream quickly.
  • Compared to tablets, less excipients is required to prepare the capsule.

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Friday, June 26, 2020

Advantages of tablets over capsules

The medicine or drug can be administered in a variety of pharmaceutical dosage forms. It may be as intravenous or oral medication. Solid and liquid medicines are types of oral medication. Solid medication is either taken in tablet or capsule form. Both tablets and capsules are most commonly prescribed as an oral solid dosage form. However, both have some similarities like both are solid dosage form, work similarly, both have excipients, both are used for treatment. But they also have some major differences.
The advantages of a tablet over the capsule are as follows.
  • The major advantage of the tablet over the capsule is that the tablet can come in a fast release, delayed-release, sustained-release, or extended-release type, which is not available in the capsule.
  • The stability of the tablet is higher than the capsule, as it is less affected by moisture, air, and light, etc.
  • Special conditions are not required to store tablets.
  • Unlike capsules, tablets can be cut into two or more pieces if small doses are required.
  • The tablets are cost-effective compared to capsules, as the medicine and excipients of capsules need to be packed in hard or soft gelatin shells.
  • Tablets can be manufactured in custom sizes, shapes, and colors.
  • For those who have difficulty swallowing, especially for children, sick patients, several tablets are available as chewable or orally dissolving tablets.
  • The shelf-life of the tablets is longer and it comes in several forms.
  • The tablet accommodates a higher dose of the active ingredient than the capsule.
  • The manufacturing process of tablets in pharmaceutical industries is easier than that of capsules.
  • Tablets are available in a wide variety of sizes and shapes.
  • The tablet is very stable and retains drug potency compared to capsules.

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Thursday, June 25, 2020

Advantages and disadvantages of tablets

The tablet is the most commonly prescribed solid dosage forms. Generally, it is intended for oral routes of administration. It is prepared by compressing powdered active pharmaceutical ingredient (API) with different excipients. The table is a flat, rounded in shape and differs in shape, size, and weight depending on the drugs used to prepare. Tablets usually contain flavoring agents, coloring agents, lubricants, diluent, filler, disintegrants, binder, anti-adherent, and some other excipients. Tablets are the most broadly used solid dosage forms due to the increasing advantages and popularity day by day.

Tablets- solid dosage form

 Advantages of tablets:
  • The major advantages of tablets have dose accuracy, stable dose, high precision, and lowest variability.
  • Tablets are cheaper than other dosage forms and are economical for packaging, transport, and storage.
  • It is easy to swallow, and in some cases, it can easily dissolve in water for feeding for children.
  • It is providing protection of drugs (API) from atmospheric conditions such as moisture, air, and light, etc.
  • Sugarcoating the tablet masks the unpleasant taste and smell of the drugs, hence it can be simply administered.
  • Tablets have a low production cost and mass production is possible as compared to the other dosage forms (capsule, liquid), as it is easier to prepare.
  • Tablets can provide flexibility in dosage form by creating a special release product such as a delayed-release, sustained release, and a rapidly dissolving tablet.
  • Whenever a partial dose is required, it is easy to divide into parts, which is not possible in capsules.
  • Tablets are most stable in chemical, physical, and microbiological properties.
  • It does not harm the gastrointestinal tract, as it easily and quickly digested.
  • Administration of the minute dose of the medicine is possible because it provides the exact amount.
  •  Tablets can be attractive as they vary in color.
  • As compared to liquid dosage form, it does not require much space for storage, and the production, packing, and handling is cheaper.
Disadvantages of tablets:
  • The major disadvantage of a tablet is that it is difficult to swallow, especially for children, sick, and unconscious patients.
  • Low density and amorphous APIs are difficult to compress in the tablet punching machine.
  • Drugs that are hygroscopic in nature are not suitable for compressed tablets.
  • Certain types of pills can cause problems in bio-availability.
  • Oxygen-sensitive drugs require special coating.
  • Drugs that have poor or low solubility in water, slow dissolution rates, and high absorption in the gastrointestinal tract may make them difficult to formulate.
  • Production costs can increase due to the coating and encapsulation of the tablet.
  • Sometimes due to unpleasant taste and odor, patients experience discomfort and avoid swallowing.
  • The manufacturing of tablets in the pharmaceutical industry requires complex and expensive machines.
  • Some medicines cause gastric irritation while administered in tablet form.
  • There is an unlimited amount of a unique mix of ingredients that can only be placed in capsules, not tablets.

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Tuesday, June 2, 2020

What are the different types of columns used in HPLC

Different types of HPLC columns are used to separate the analytes according to nature, composition, and separation modes of HPLC.

The column is the basic component in the analysis of the high-performance liquid chromatography as it is responsible for the separation of compounds. The sample solution moves through the column along with the mobile phase and it comes out of the column as the separate into its components. In general, silica gel is filled in columns due to its porosity and size of particle which helps to separate the compounds, and it is also inert solid support which does not react with solvents. Thus the silica columns are used in the analysis of compounds. Liquid chromatography can be classified into several modes. If the classification of chromatography depends on the stationary phase and the nature of the separation method, then it may be adsorption chromatography, size exclusion chromatography, and ion-exchange chromatography. With respect to the first type, there are two separation modes are based on polarity which is reverse-phase chromatography and normal-phase chromatography, these modes cover about 90% of all chromatography applications. 


There are various types of HPLC columns are available for liquid chromatography depending on their composition and separation system, let’s check it.

Reversed-phase HPLC columns:

The reversed-phase chromatography has a non-polar stationary phase and a polar mobile phase. Bonded hydrocarbons such as C8 and C18 and other non-polar hydrocarbons are used in reverse phase columns as a stationary phase, while an aqueous organic solvent such as acid, buffer, methanol, acetonitrile, or a suitable mixture of it is used as a mobile phase. The isolation of molecules in reversed-phase columns often takes place based on the sample polarity, but this is unlike the normal phase HPLC column so this type of chromatography is known as reverse phase chromatography.
The commonly used columns in reversed-phase are:
  • C18 RP-HPLC columns
  • C8 RP-HPLC columns
  • Alkyl reversed-phase columns
  • Phenyl reversed-phase columns
  • C4 RP-HPLC columns
  • C1 RP-HPLC columns
  • C30 RP-HPLC columns

Normal phase HPLC columns:

Normal-phase chromatography is a type of liquid chromatography it is used for the isolation of positional isomers which are complex to separate in RP-HPLC. The normal-phase chromatography has a more-polar stationary phase and a non-polar mobile phase. The solid support of the column is more polar hence rather than the water hexane, methylene chloride chloroform, diethyl ether, or a mixture of these used as mobile phase. Separation in normal-phase chromatography is based on the polarity of the analytes; more polar analytes interact more with the stationary phase.
The commonly used columns in normal-phase are:
Silica normal phase columns: these are potent and efficient column for isolating non-polar and moderately polar isomeric molecules.
Amino normal phase columns: These types of columns are mainly useful for the isolation of carbohydrates.
Cyano normal phase columns:  These types of columns have an optional selectivity and are more rapidly equilibrated, providing better suitability for normal phase gradient isolation than unbonded silica columns

Ion-exchange HPLC columns:

Using these columns, the molecules which can quickly ionize are analyzed. In these columns, the stationary phase remains acidic or basic for a positive or negative charge, whereas a polar mobile phase used in the form of a salt solution in water. The isolation of components takes place between the components and the charged stationary phase based on the attractive ionic force. For stationary phase different mediums are used, the most generally used immobilized charged groups are trimethylaminoethyl, diethyl-2-hydroxypropylaminoethyl, triethylaminoethyl, diethylaminoethyl, aminoethyl, sulphomethyl, sulphopropyl, and sulpho. Successful column packing is a significant aspect of ion-exchange chromatography. Polystyrene is used for the separation of small molecules in amino acids as a medium. The cellulose medium can be used to isolate large solutes since they have large pores. 

Size-exclusion HPLC columns:

Size exclusion chromatography (SEC) is also known as gel filtration chromatography. The size exclusion chromatography columns are typically filled with porous polystyrene divinylbenzene or silica particles. These columns are generally used for the analysis of synthetic polymers in organic solvents, whereas to separate the biopolymers the silica-based columns are used. The porous stationary phase in these columns allows the analytes to be separated as per their size. Small sample components enter the pores of the stationary phase, whereas larger molecules partially penetrate the pores. Thus the bigger sample components are eluted rapidly than the small molecules. Generally, these columns are not used for the analysis of pharmaceuticals.

Different types of gels in HPLC columns: 

Silica gel: Silica gel is the most commonly used packing material. There are two types of silica gels are available such as spherical and irregular shape, out of these the spherical shaped gels are most commonly used. The silica gel used in liquid chromatography has a pore on the surface; it gives a bigger surface area than without holes. The 5μm is the most widely used size, although smaller sized 1.5 to 3μm gels is also used in HPLC columns.
Polymer gel:  Silica gels are commonly used in HPLC development, although, polymer-based columns are also well-liked. Polyethylene and polypropylene are commonly known polymers for column packing. Columns of polymer gel are available in very small particles, like the silica gel. 
Other gel: In addition to silica and polymer gels, the gels used include natural substances such as cellulose, chitosan, dextrin, and ceramics are used in liquid chromatography to isolate analyses but have very limited use.
The column is the most important part in the HPLC system, the actual isolation of molecules of the sample mixture happens in the column. A column is located after the injector where the mobile phase is in contact with the stationary phase, forming an interface with the enormous surface. In recent years, the development of most chromatography has contributed to the creation of several different methods for through this interfacial contact. Usually, RP-HPLC columns are available in lengths of 30 to 250 mm, the diameter of 01 to 05 mm, and pore size of 03, 05, and 10 μm. 

Commonly asked questions on chromatography are as follows.

How many types of HPLC are there?
Depending on the stationary phase in the process, there are 4 types of HPLC, such as normal Phase HPLC, reverse phase HPLC, size-exclusion HPLC, and ion-exchange HPLC.

What is the difference between C8 and C18 HPLC columns?
The main difference between the C8 and C18 columns is their carbon atoms. C8 has 8 carbon atoms, whereas C18 has 18 carbon atoms. C8 has a small carbon chain, whereas C18 has a longer carbon chain. C8 has a short, whereas C18 has longer retention time (RT).

Which type of HPLC detector is most widely used?
The UV/VIS and PDA detectors are the most commonly used detector in HPLC as they give superior sensitivity for light-absorbing compounds.

Which is better GC or HPLC?
The gas chromatography (GC) is better for the separation of volatile compounds, whereas the high-performance liquid chromatography (HPLC) is better for the separation of less volatile samples.

What is the basic principle of chromatography?
There are different types of chromatography, although they operate on the same principle. They have a stationary phase and a mobile phase. The mobile phase has a sample mixture moves on the stationary phase, some solutes have an affinity for the stationary phase will travel slowly, While solutes that do not interact with the stationary phase will move faster.
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