Home Medicines Dosage forms of drugs: capsules, pills, syringes

Dosage forms of drugs: capsules, pills, syringes

by Josephine Andrews
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There are different dosage forms of medicines such as tablets, suppositories or injections. Which one is most suitable depends, for example, on where or how quickly the active substance is to be released or for whom the drug is primarily intended. Learn more about the many ways to administer medicines!

What types of tablets are there?

Tablets are solid, single-dose dosage forms with one or more active ingredients and excipients, which are usually pressed from dry powders or granules under high pressure in special machines.

There are many different tablets, such as chewable, lozenge, effervescent and film-coated tablets. It is often important to take tablets with sufficient liquid. A glass of water is a guideline.

Uncoated and coated tablets

Uncoated tablets are mono- or multi-layer tablets where the structure has no specific influence on the release of the active ingredient. They disintegrate very quickly within 15 minutes.

There are also tablets that are coated with different materials . These can be, for example, thin polymer coatings ( film tablets ) or sugar coatings ( coated tablets ).

effervescent tablets

These are uncoated tablets that rapidly dissolve upon contact with water, releasing carbon dioxide. With the liquid, the active ingredient quickly reaches the stomach and small intestine , which means that the effect begins quickly.

Dissolving or dispersing tablets

These are tablets for making a solution or dispersion (fine distribution of one substance in another), which is then taken. They can be uncoated tablets or film-coated tablets. They are dissolved or dispersed in water before ingestion.

orodispersible tablets

Orodispersible tablets are uncoated tablets that quickly disintegrate in the mouth before being swallowed.

lozenges and lozenges

These are tablets that slowly release their active ingredient(s) in the oral cavity when sucked. This is said to have either a local effect or – after absorption through the mucous membrane into the blood – a systemic effect (acting throughout the body).

Sublingual and buccal tablets

These tablets are placed under the tongue (sublingual tablets) or in the cheek pouch (buccal tablets), where they slowly dissolve. The released active ingredient is absorbed into the blood via the mucous membrane.

Modified-release tablets

Sometimes uncoated tablets and film-coated tablets contain excipients that determine the rate, location or time of drug release. In this way, the active ingredient can be released over a longer period of time (sustained-release tablet), in a delayed or pulsating manner.

Enteric coated tablets

This refers to film-coated tablets or so-called matrix tablets* with a delayed release of the active ingredient, which withstand the acidic contents of the stomach and only dissolve in the small intestine.

*In the case of matrix tablets, the evenly distributed active ingredient is embedded in a framework material (matrix). In some cases it is released from it through pores (heterogeneous porous matrix), in other cases it escapes through the matrix material to the outside (homogeneous non-porous matrix). There are also matrix tablets in which the active ingredient is released from a porous framework (continuous matrix).

chewable tablets

This type of tablet is chewed and swallowed. Some of the active ingredient is already released in the mouth and absorbed through the oral mucosa. The remaining part reaches the stomach.

The advantage of chewable tablets is that the active ingredient is absorbed quickly and the effect sets in quickly. Certain excipients ensure that the chewable tablets taste pleasant.

Lyophilisate tablets

This is a special form of tablet that is produced by freeze-drying and is intended for use in the oral cavity or for dispersion (fine distribution) in water. These tablets dissolve in fractions of a second when they come into contact with saliva or water.

What types of capsules are there?

Capsules are shaped hollow bodies of different sizes. They usually contain single-dose, solid active ingredients, but sometimes also pastes, viscous liquids or melt preparations. Capsules also refer to dosage forms in which the active ingredient is hermetically sealed in gelatine or another suitable substance.

hard capsules and soft capsules

Hard capsules do not contain any plasticizers in the capsule material and therefore have a harder consistency.

The soft capsules, which contain softeners (such as glycerol and sorbitol) in the capsule material, are different.

wafer capsules

They usually consist of rice flour and are briefly dipped in water before use: the starch contained in the rice flour swells up, which makes it easier to take the wafer capsules.

Today, this dosage form only plays a subordinate role – partly because it is complex to produce and susceptible to moisture.

Modified-release capsules

These capsules contain excipients that determine the rate, location, or timing of drug release. In this way, the active ingredient can be released over a longer period of time (sustained-release capsule), delayed or in a pulsating manner.

Enteric-coated capsules

These are capsules with a delayed release of active ingredients, which withstand the acidic contents of the stomach and only dissolve in the small intestine.

What types of powder are there?

Powders consist of fine particles of matter. They can contain one or more active ingredients and excipients. The individual powder particles can differ in shape, size and mass up to a certain limit.

Although powder counts as an independent dosage form, it is mostly used to manufacture other dosage forms (e.g. capsules containing powder).

oral powder

Powders are usually dissolved or suspended in water before ingestion. For this purpose, effervescent components (such as hydrogen carbonates) can also be added (= effervescent powder).

Powder for cutaneous use

Powders for cutaneous use are also called powders. The individual particles are usually less than 100 micrometers in size and are therefore not perceived as annoying on the skin . Depending on the type of application, a distinction is made between wound powders, fat powders, astringent (= contracting), disinfecting, antibiotic and antipruritic powders.

What types of granules are there?

Granules are created by granulation (dry granulation, melt granulation, build-up granulation, etc.) of powders. Each grain of granulate is a construct made up of several powder particles that stick together so tightly that further handling is possible. The surface of these granules is correspondingly porous.

Similar to powders, granules count as an independent dosage form, but are mostly used to produce other dosage forms (e.g. tablets).

effervescent granules

These are uncoated granules that quickly dissolve when they come into contact with water, releasing carbon dioxide.

direct granules

Granules that do not have to be dissolved in water before use are referred to as direct granules. They come in handy little bags that can be emptied directly into the mouth when needed.

Coated granules

Such granules are coated with different materials, for example with polymers.

Enteric-coated granules

Like their tablet and capsule counterparts, these granules are coated with an enteric coating. As a result, the granules only dissolve in the small intestine.

Modified-release granules

These are coated or uncoated granules that contain excipients that determine the rate, location, or time of drug release.

What types of rectal preparations are there?

Preparations for rectal use (i.e. for use via the anus) serve either diagnostic purposes or are intended to exert a therapeutic effect – either locally or systemically (affecting the whole body).

By far the most common form of rectalia are suppositories. There are also other solid, semi-solid and liquid rectalia.

suppositories

Suppositories are unit-dose, shape-retaining preparations that are inserted into the rectum . They usually have an elongated “torpedo shape” and melt at body temperature.

In terms of weight, the suppositories for adults (2 grams) and those for children (1 gram) differ. Depending on whether the active ingredient is suspended or dissolved in a suppository, one speaks of suspension or solution suppositories.

rectal tampons

These are medicated tampons designed to remain in the lower rectum for a period of time. These rectal tampons are often suppository-like preparations that contain a gauze insert for better local fixation.

rectal capsules

Rectal capsules are soft gelatine capsules with a polymer coating and an elongated, often torpedo-shaped structure. They are briefly moistened with water before insertion. Rectal capsules are packed in moisture-proof medicine jars or sealed plastic or aluminum foil.

rectal solutions and suspensions

These enemas are used for local treatment (e.g. for chronic inflammatory bowel diseases) or as a laxative. The solutions or suspensions are either already packed in ready-to-use bags or bottles or are freshly prepared before use by dissolving solid dosage forms such as tablets or powders.

rectal foams

Rectal foams are medicated foams for rectal use. They are used much like an enema.

Foams have the advantage that the active ingredient they contain is well distributed. Surface-active additives ensure the formation and stability of the foam, which is generated from a liquid preparation with the help of propellant gas.

Semi-solid preparations for rectal use

The rectalia also include ointments, creams and gels that are applied rectally with or without an applicator. So that the active ingredients are better absorbed, such preparations are usually lipophilic (fat-soluble).

What types of vaginal preparations are there?

Preparations for vaginal use are primarily intended for local therapy and for this reason often contain anti-inflammatory, antimycotic (effective against fungi) or antiseptic (effective against germs in general) drugs in a suitable base.

vaginal suppositories

Unlike suppositories, vaginal suppositories have an egg-shaped (“ovula”) shape. The two dosage forms also differ in terms of mass, which is between two and six grams for vaginal suppositories.

In order to evenly moisten the vaginal mucosa, vaginal suppositories usually consist of a macrogol mass, which is poured into special molds similar to suppositories.

vaginal tablets

These are compressed tablets with or without a water-soluble coating. They often contain lactose (milk sugar) and cellulose as excipients. Vaginal tablets must not have any sharp edges so that they cannot injure the delicate vaginal mucosa.

vaginal capsules

Soft gelatine capsules, the shape of which is adapted to vaginal use, are used as vaginal capsules.

vaginal tampons

They consist of active substance-containing cotton wool or gauze or active substance-containing cellulose. However, this form of vaginal preparations hardly plays a role in practice.

Semi-solid preparations for vaginal use

These are mostly water-soluble ointments, creams or gels that are inserted into the vagina and/or applied externally in the genital area. For internal use in the vagina, there is usually a suitable applicator in the medication pack.

vaginal foams

They are inserted via a pressurized gas pack with special valves and an applicator for insertion into the vagina. The active ingredient is dissolved in an emulsion that turns into a foam with the help of propellant and surface-active additives.

Solutions, suspensions and emulsions for vaginal use

Solutions, suspensions and emulsions are liquid preparations that are inserted into the vagina using an applicator. They are often used for rinsing or have a local effect.

What types of semi-solid preparations are there?

Semi-solid preparations for cutaneous use are colloquially referred to as “ointments”. These are spreadable dosage forms for use on healthy, diseased or injured skin. The active ingredients incorporated can either be dissolved (solution ointments) or suspended (suspension ointments).

Such preparations are almost always used for local therapy. To put it simply, they consist of a base (vehicle) and the active ingredient or a combination of active ingredients. In contrast to other medicines, ointments, creams and the like are also assumed to have an effect without the addition of active ingredients.

ointment

Ointments are anhydrous preparations from a uniform (single-phase) basis. Depending on their properties, a distinction is made between hydrophobic ointments (“water-avoiding”, can only absorb small amounts of water), hydrophilic ointments (“water-loving”, can absorb larger amounts of water) and hydrophilic (miscible with water) ointments.

cream

Creams are multi-phase preparations consisting of a fatty (lipophilic) and an aqueous (hydrophilic) phase. In order to combine these two actually immiscible phases, creams often contain so-called emulsifiers.

A distinction is made between lipophilic (” fat -loving”), hydrophilic (“water-loving”) and amphiphilic (“fat and water-loving”) creams.

gel

Gels are liquids that have been gelled using a suitable gelling agent. As a rule, this means hydrophilic gels in which water gels with the addition of gelling agents such as cellulose or carbomers to form a spreadable mass.

But there are also lipogels (oleogels) in which paraffin is gelled with silicon dioxide, aluminum or zinc soaps. It is difficult to distinguish such preparations from hydrophobic ointments.

paste

Pastes contain large proportions of finely divided powders in their basis. The higher the powder content, the thicker and harder a paste is.

When exactly a paste is no longer an ointment, but is considered a paste, is not precisely defined in the pharmacopoeia. Normally, ointments with a solids content of at least 20 percent are referred to as pastes.

envelope paste

It consists of a hydrophilic, heat-storing base in which the active ingredients are dissolved or suspended. In contrast to normal pastes, envelope pastes are used not only when cold, but also when warm. For this purpose, the envelope paste is applied sufficiently thickly to bandage material, placed on the affected area and covered with a cloth.

What types of oral liquids are there?

Liquids for oral use are divided into solutions, emulsions, suspensions, drops and syrups.

oral solutions

A solution is a liquid medicine that contains active ingredients and excipients in a dissolved form, making them easy to swallow. Solutions are particularly suitable for small children and patients with swallowing problems.

There are also solutions for external use (e.g. on the gums).

emulsions for oral use

Emulsions are systems of two or more immiscible liquids (e.g. oil in water). By adding emulsifiers, emulsions can be stabilized for a limited period of time.

However, they always show a tendency to phase separation, which is why they have to be shaken up before each use. This ensures an even distribution and thus dosing.

There are also emulsions for external use, for example in the form of a skin cream.

oral suspensions

Suspensions are liquid preparations in which solid particles are distributed but not dissolved. Similar to emulsions, they show a strong tendency to phase separation (the solid particles sink to the bottom), which is why they have to be shaken up before each use. As with the emulsions, the aim is to ensure an even distribution of the particles contained and thus the correct dosage.

Suspensions for topical use are also available (e.g. for use on inflamed skin).

oral drops

Drops are liquid medicines that are filled into a dropper bottle. The active substance can be dosed individually using a dropper insert or a pipette.

syrups

A syrup is a viscous, sweet-tasting, watery liquid. Classic syrups consist of a mixture of sugar and water. Newer sugar-free variants contain various gelling agents and sweeteners or sugar substitutes such as sorbitol.

Powders and granules for the preparation of solutions or suspensions

These are ready-to-use and pre-dosed powders or granules that can be used to make oral solutions or suspensions by adding water. A well-known example is antibiotic dry juices.

Powder for making drops for oral use

There are also ready-made and pre-dosed powders that can be used to make oral drops by adding water.

What types of chewing gum are there?

Chewing gums containing active ingredients are solid, single-dose preparations consisting of an insoluble chewing base. They are chewed to achieve either a local effect or a systemic effect (after absorption of the released active ingredients through the mucous membrane into the blood). A well-known example is nicotine chewing gum for smoking cessation.

What types of patches are there?

Plasters are flexible, adhesive preparations intended for external use.

Drug-free patches

Small wounds such as abrasions or the puncture site after taking blood are covered with a conventional plaster that does not contain any active ingredients.

Medicated plasters

Plasters containing active ingredients have a different purpose than just covering a wound. Active substances intended for local or regional therapy (e.g. corn plasters) are incorporated into their adhesive mass.

transdermal patches

They are also called transdermal therapeutic systems (TTS). The difference to patches containing active ingredients is that TTS release the active ingredient into the bloodstream, which allows a systemic effect to be achieved (e.g. pain patches, contraceptive patches ).

What types of parenteral preparations are there?

Parenterals are sterile injection and infusion preparations that are prepared from powders or concentrates by diluting them with a suitable liquid. Its name is derived from the Greek “par enteron” (= outside the intestine) and means something like “bypassing the gastrointestinal tract”.

These preparation forms can be introduced, for example, under the skin (subcutaneously, sc), into a muscle (intramuscularly, im) or into a vein (intravenously, iv). This is advantageous for active ingredients that would dissolve in the gastrointestinal tract or cannot be absorbed through the intestinal mucosa (e.g. proteins, larger active ingredient molecules, unstable drugs).

Another advantage of parenterals is that the onset and duration of action can be controlled very well. In addition, parenterals can also be used in unconscious patients (in contrast to tablets, for example).

Disadvantages are the high costs and the strict requirements for the sterility of the preparations: Since they are administered directly into the bloodstream, parenterals have to meet strict sterility requirements, which can only be met in special production facilities set up specifically for this purpose.

injection preparations

These are sterile aqueous or oily preparations (solutions, emulsions or suspensions) that are administered by syringe. Only a few milliliters are injected.

infusion preparations

These are also sterile aqueous or oily preparations (solutions, emulsions or suspensions). However, they are not administered by injection, but by infusion . And the amount administered is much larger than with an injection.

concentrates

Apart from the ready-to-use injection and infusion preparations mentioned above, there are also sterile concentrates which only result in an injection or infusion preparation when a suitable sterile liquid is added.

powder

Similar to concentrates, sterile powders can also be used to prepare an injection or infusion by adding a suitable sterile liquid.

pre-filled syringes

Pre-filled syringes (or pens) already contain the liquid intended for injection in a ready-to-use and pre-measured form. Frequently contained active ingredients are whole proteins (e.g. insulin for diabetics), peptides (e.g. GLP-1 receptor agonists like liraglutide – also used as a diabetes drug) or antibodies (e.g. anti-TNF antibodies like adalimumab – for example against rheumatoid arthritis or Crohn’s disease).

What types of inhalers are there?

Inhalers are devices for inhaling medicines. Inhalanda (the active substances for inhalation) can either be dissolved in water or presented as a dry suspension. These are liquid or solid dosage forms that are used in the respiratory tract as a vapor, aerosol or powder in order to achieve a local or systemic effect.

metered dose inhalers

A metered dose inhaler contains a pressure-tight container with the active substance in a liquid whose boiling point is below room temperature (ie it evaporates immediately when it leaves the container) and a propellant.

If the metered dose inhaler is used, part of the solution (or suspension) escapes. The liquid vaporizes explosively – the active ingredient is finely distributed. The resulting aerosol cloud leaves the dosing aerosol at high speed.

In order to prevent a large part of the active ingredient from flaking off the throat wall and being swallowed ineffectively, patients must coordinate their inhalation maneuver precisely with the triggering of the metered-dose aerosol.

Correct handling should be checked regularly by a doctor or pharmacist.

powder inhalers

Dry powder inhalers (DPI) contain the active substance in the form of a powder, which is automatically atomized by the force of the air flow when you inhale and reaches the lungs . The powder can either be “reloaded” individually as a capsule (capsule inhaler) or in the form of a so-called multi-dose system (eg Diskus, Turbohaler).

The advantage of DPI lies in its ease of use. They do not require coordination between inhalation and release, as is the case with a metered dose inhaler. However, for the correct use of dry powder inhalers, a sufficiently strong inhalation maneuver is required (so-called inspiratory flow).

Correct handling should be checked regularly by a doctor or pharmacist.

Dual jet impaction inhalers

This type of inhaler oscillates between a nebulizer and a metered dose inhaler. On the one hand, this is due to the fact that the resulting aerosol cloud is comparatively slow and long-lasting (cf. nebulizer), and on the other hand to the handiness of the device (cf. metered-dose aerosol).

Dual jet impaction inhalers release the aerosol using a spring that is tensioned prior to use. The spring-generated pressure directs the fluid through two channels that are at a fixed angle to each other. When the two jets of liquid meet, extremely fine aerosol droplets are created at low speed, which are easy to inhale.

Correct handling should be checked regularly by a doctor or pharmacist.

nebulizer

These are electrically operated stationary devices that atomize and continuously release the liquid they contain with the help of ultrasound or compressed air. The particle size and speed are extremely beneficial for inhalation. Due to the low concentration of active ingredient per breath, however, an inhalation time of ten to 20 minutes is required.

Nebulizers must be cleaned regularly by hand.

What preparations are available for use on the eye?

Preparations for use on the eye are called Okularia. Their therapeutic effect is usually localized to the eye or adjacent tissue. There are special requirements with regard to their freedom from germs.

eye drop

Sterile, liquid preparations for use on the eye are called eye drops. Once opened, they have a limited shelf life. A distinction is made between aqueous and oily eye drops.

Aqueous eye drops must meet certain conditions regarding the following criteria:

  • sterility
  • clarity
  • preservation
  • stability
  • PH value
  • viscosity

In the case of oily eye drops , the contact time of the active ingredients on the eye is longer, which can definitely be desirable. And the oily drops have to meet far fewer requirements than the watery ones. As a result, they are easier to manufacture. Last but not least, some active ingredients can only be used in the form of oily preparations.

However, the oily consistency temporarily impairs vision.

If you have to use two different eye drops, they should be at least 15 minutes apart. When using aqueous and oily drops, the aqueous ones should be instilled first.

eye baths

Sterile, aqueous solutions are used as eye baths to rinse the eye or soak eye compresses with it. This is mainly done after injuries, chemical burns or burns in the eye area.

Eye baths have a limited shelf life once opened.

powder

There is also the option of making eye drops and agent baths from a powder. These powders form their own category in the European Pharmacopoeia.

semi-solid preparations

Eye ointments are semi-solid, sterile preparations intended for use on the conjunctiva , cornea, or eyelid . They have to meet significantly stricter requirements than conventional ointments and creams, for example in terms of sterility and particle size.

Application temporarily impairs vision.

If you need additional eye drops, you should use them first and only then apply the eye ointment.

eye insert

Ophthalmic inserts are sterile, solid or semi-solid preparations for use in the conjunctival sac. The embedded active ingredient is released here with a time delay via a special matrix. There are biodegradable and non-degradable systems.

What preparations are available for use on the ear?

Preparations for use on the ear (= Auricularia) are liquid, semi-solid or solid preparations that contain one or more active ingredients. Their effect is limited to the external auditory canal.

If the preparations are to be used for a tear or hole in the eardrum ( eardrum perforation ) or before and after an ear surgical procedure, they must be sterile, unpreserved and filled in sterile single-dose containers.

ear drops and ear sprays

Suspensions, emulsions or solutions in suitable liquids (e.g. glycerol, water, fatty oils) are used as ear drops and ear sprays and are introduced into the external auditory canal.

Semi-solid preparations for use on the ear

Ointments and creams are available as semi-solid preparations for use on the ear. They are inserted into the external auditory canal with an enclosed applicator.

Ear powders, rinses and tampons

Ear powder can also be placed in the external auditory canal with a suitable applicator.

Ear rinses are aqueous solutions that are used to clean the outer ear canal.

Medical tampons are used as ear tampons. They are placed in the external auditory canal.

What preparations for use in the nose are there?

Preparations for use in the nasal cavities (= nasals) are liquid, semi-solid or solid preparations with one or more active ingredients. They are intended to achieve either a local or a systemic effect.

nasal drops and nasal sprays

There are different solutions, emulsions or suspensions for dripping or spraying into the nasal cavities. Nasal sprays can be placed on the market in containers with a spray device or in pressurized containers.

Semi-solid preparations for nasal use

Ointments and creams can be applied to the nasal cavities with the included applicator.

nose powder

These are powders containing active ingredients that are blown into the nasal cavities with a suitable applicator.

nasal rinses

Aqueous solutions are used to rinse the nose. They serve to clean the nasal cavities.

nose pins

These are cylindrical or conical, solid preparations containing active ingredients that are inserted into the nostrils and are intended to produce a local effect (e.g. nose pins to stop bleeding from nosebleeds).

What types of preparations for use in the oral cavity are there?

Oromucosal preparations are liquid, semi-solid or solid preparations that can produce a local or systemic effect.

gargling solutions

Gargling is done with aqueous solutions, which usually have a neutral pH and can have a local effect. There are ready-to-use gargle solutions as well as tablets, concentrates and powders, from which a gargle solution can be made by adding liquid.

mouthwashes

Mouthwashes are also aqueous solutions with a mostly neutral pH value. The mucous membrane of the oral cavity is rinsed with it and the solution is then swallowed (mouthwashes should not be swallowed!). Mouthwashes can also be ready-to-use or made from tablets, concentrates and powders.

Solutions for use on the gums

They are applied to the gums using a suitable applicator.

solutions and suspensions for use in the buccal cavity

Both preparations are applied to the mucous membranes of the oral cavity using a suitable applicator. However, suspensions must be shaken before use.

Semi-solid preparations for use in the oral cavity

They are available in the form of hydrophilic gels or pastes and are used in the oral cavity or on the gums. They are offered in multi-dose and single-dose containers.

spray

A distinction is made here between preparations for local use (drops, sprays) and those for systemic use (sublingual sprays). They are placed in the mouth or throat or under the tongue (sublingual).

lozenges and lozenges

These are single-dose preparations that are sucked for the purpose of a local effect and slowly dissolve in the process. Lozenges are pressed like normal tablets, lozenges are poured into molds like suppositories and packed after hardening.

Capsules for use in the oral cavity

Most are soft capsules that are either chewed or sucked.

mucoadhesive preparations

They adhere particularly well and for a long time to the mucous membrane of the cheeks, so that the active ingredients they contain can be absorbed (resorbed) by the body. Mucoadhesive preparations must be sufficiently strong not to crumble or break.

What special dosage forms are there?

Medicinal baths

Medicinal baths contain various ingredients such as fats, essential oils, organic compounds (e.g. sulphur), sea salt, plant extracts and/or tanning agents. The bath additives are used for full or partial baths.

shampoos

These liquid or viscous preparations are applied to the scalp and then washed out with water. In addition to active ingredients, they can also contain suitable auxiliaries for preservation, storage life and/or stability.

Active ingredient foams

Active substance foams are preparations in which a large volume of Gs is distributed in a liquid phase. The addition of a surface-active substance ensures the stability of the resulting foam. Foams for use on open wounds or severely damaged skin must be sterile.

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