Drug Delivery Via The Oral Route Biology Essay

Drug bringing via the unwritten path is presently the most recognized method of drug disposal in the UK.1 With advantages such as patient convenience and low fabrication costs,2 pharmaceutical companies have prioritised peroral preparations over any other path of administration.1 Peroral preparations nevertheless are flawed in that anterior to systemic soaking up, active pharmaceutical ingredients ( APIs ) incorporated within the preparation are extremely susceptible to hepatic metamorphosis and debasement via enzymes within the GI piece of land ( GIT ) .3 Furthermore dose signifiers, such as tablets and capsule, are inconvenient to patients who have trouble in swallowing3 or suffer from nausea.4

The medical term for ‘difficulty in get downing ‘ is dysphagia and this status frequently affects kids and elderly.3 For pediatric patients there are options such as liquid dose signifiers available, nevertheless these present several disadvantages including instability of the drug, conveyance jobs due to bulkiness of the merchandise and inaccurate dosing.5

An alternate preparation, unwritten disintegrating tablets ( ODTs ) , has been developed maintaining easiness of get downing in mind.6 ODTs allow rapid soaking up through the unwritten pit and therefore extinguish premature hepatic metamorphosis of API, GI debasement and do lesser systemic side effects than those associated with peroral dose forms.7 ODTs make it easy for the patient to get down and they require no H2O during disposal accordingly doing them more acceptable for dyphagic patients.6

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ODTs, nevertheless, are delicate in nature and present high exposure towards wet therefore missing in strength and stability.7 Furthermore re-educating patients on the right method of disposal of ODTs has proved hard since patients frequently do non read cardinal information on labels such as “ do non get down ” or “ do non masticate ” .1

The issues related to unwritten dose signifiers are widely acknowledged by the pharmaceutical industry and therefore pharmaceutical companies are ever concentrating on the development of fresh unwritten preparations which allow even quicker systemic soaking up ( than 30seconds – recorded clip for ODTs8 ) through the unwritten pit, one of which is Oral Disintegrating Films ( ODFs ) .

Chapter 2

Oral Disintegrating Films

ODFs are stamp sized films1 with a thickness of about 70Aµm9 ( figure 2-111 ) . When placed in the oral cavity, ODF adheres to the lingua or any other mucosal surface exciting saliva11. Within seconds the movie disintegrates and releases APIs from the movie. APIs are quickly absorbed into the bloodstream11 for systemic or local action.12 The speedy soaking up of ODFs means the curative response is obtained faster compared to peroral dose forms.Fast Dissolving Film

Figure 2: A representation of an ODF ( Courtesy of Hughes medical corp11 ) Background

The production of transdermic spots incepted the construct of ODFs11. By 2001 ODFs were produced by pharmaceutical companies such as Pfizer and marketed as unwritten attention products.13 Over the last decennary over 50 pharmaceutical companies within the US market, such as Lavipharm, have incorporated APIs into these formulations14 ( table 2-1 ) with the purpose of bring forthing a more comfy manner of presenting the preparations. I WAN NA FORGET THE COMPLIANCE IN INTRO TOTALLY – I THINK YOU SHOULD Mention THIS IN YOU DISCUSSION AS LITERALLY ONE POINT? novel technique for drug bringing, which presented the potency in bettering issues related to compliance.14


Trade name


Strength ( milligram )


Gas – Ten






Diphenyhdramine HCl

Phenylephrine HCl








Medical Corp

Folic Acid






Table 2: Some of the ODFs available within the US market, the concentration of API nowadays within each strip and the Pharmaceutical Manufacturer. 3,14 Abbreviations ; API: Active Pharmaceutical Ingredient, HCl: Hydrochloric Acid milligram: Miligrams

ODFs within the UK

In 2002 Wrigley ‘s released an ODF marketed as a new ‘non-chewing gum ‘ into the confectionary market called ‘Extra Thin Ice’.15 Harmonizing to an article written in The Grocers magazine,16 Wrigley ‘s ODFs made a net income of ?14m in the first 12 months of debut ; nevertheless in 2007 their gross revenues plunged and due to hapless publicizing their impact on the market was limited.16 Although there is no official grounds to explicate why these are no longer available, many cyberspace beginnings point towards low public acceptableness towards the ODFs.17

The UK pharmaceutical market has merely adopted the usage of ODFs for limited conditions. Presently in the UK there are snoreeze unwritten strips available nonprescription ( OTC ) 1,18 ( AND POSSIBLY NRT? ) in pharmaceuticss nationally. This includes large giants such as Boots Pharmacy, Tesco Pharmacy, Sainsbury Pharmacy and Asda Pharmacy. Boots pharmaceuticss have besides manufactured their ain trade name option strip called “ Boots Alternatives Snoring alleviation Strips ” . 18

Mechanism of API Absorption Though the Oral Cavity

Figure 2: A representation of the layout of the unwritten cavity19.The unwritten pit allows greater permeableness of drugs compared to the tegument nevertheless non every bit high as the intestine.19 Figure 2-2 is a diagrammatic representation of the unwritten mucous membrane. As can be seen in order for an API administered to make blood vass it must traverse: closely packed epithelial cells, the cellar membrane, lamina propia and eventually come in the extremely vascularised bomber – mucosa.19 Patel describes the unwritten pit and its permeableness in detail.19 Table 2-2 summarises the factors impacting drug soaking up within the unwritten pit. Note TO SELF COME BACK TO THIS



( Aµm )

Employee turnover Time ( yearss )

Surface country ( cm2 )


Residence Time

Blood Flow












Very Good













Very Good


Table 2: Features of the unwritten mucous membrane ( Table taken from Patel19 ) .

Categorization of ODFs

ODFs may be classified into three subgroups: flash release, mucoadhesive melt-away wafers and mucoadhesive sustained-release wafers. 13

They are grouped harmonizing to how they react when placed in the oral cavity. ‘Flash release ‘ are designed to let go of the API within 60 seconds of puting inside the oral cavity whereas ‘mucoadhesive thaw off ‘ and ‘mucoadhesive sustained-release wafer ‘ take proceedingss and hours respectively.13 The differences in decomposition times between the different types of ODFs, means that the rate of drug release from the preparation can be controlled by choosing the right ODF. However in making so one must accept the other belongingss of that type of ODF ( table 2-3 ) .13,20


Type of ODF

Flash Release

Mucoadhesive thaw off

Mucoadhesive sustained release

Area ( cm2 )




Thickness ( Aµm )







Gingival or other countries


Highly hydrophillic polymers

Hydrophillic polymers

Non soluble polymers

Table 2: Properties of the three subcategories of ODFs.13,20 Abbreviations ; ODF: Oral disintegrating movie, cm2: centimeters2, Aµm: microns

Advantages of ODFs

ODFs have a larger surface country than ODTs, hence decomposition and disintegration of the movies will happen at a fast rate.21

The movies provide accurate dosing, as opposed to liquid unwritten dose forms.14

They avoid drug debasement via the GIT and hepatic metamorphosis, hence allows a broad scope of drugs to be incorporated at lower doses accordingly cut downing side effects and improves cost-effectiveness.1,21, 22

Improves conformity within patients because it ‘s easier to get down and it does n’t necessitate any H2O when taking the medicine. It ‘s besides ideal for dysphagic patients or patients who are enduring from conditions such as sickness ( a common job associated with tablets and capsules ) .14,21

Some drugs degrade over clip when exposed to H2O, ODF movies can be packaged to avoid aqueous environment and exhibit greater stableness compared to liquid forms.14

ODFs are flexible and stronger compared to dosage signifiers such as ODTs and hence conveyance, storage and patient handling is significantly improved.21

Disadvantages of ODFs

The measure of API incorpotated within the movie can non transcend 50mg,13 nevertheless one exclusion is the Gas-X strip which contains 62.5mg Simethicone per strip.1

Even though dosing is accurate compared to liquid unwritten dose signifiers, it is hard to derive uniformity in dosage as seen with tablets and capsules24.

The thickness of the movie additions with the concentration of integrated API, this can sometimes compromise the belongingss of the film.13

Some drugs can degrade over clip as they are highly susceptible to hydrolytic and oxidative debasement, therefore the preparation and packaging of the movie is required to be carefully considered to guarantee stability.14

Formulation of ODFs

In order for an ODF to be accepted by patients many factors need to be considered during its preparation. These include its visual aspect, gustatory sensation, decomposition clip, oral cavity feel, and compatibility of excipients and API within the formulation.21

Table 2-4 shows the typical composing of an ODF.3


Quantity ( % W/W )


1 – 25


60 – 65


0 – 20

Fillers, Colours, Flavours etc

0 – 40

Table 2: Typical composing of an ODF.3 Abbreviations: % W/W: Percentage weight in weightBelow is an overview of all the excipients that may be incorporated during ODF preparation.

Strip forming polymers

An indispensable constituent of ODF preparation is the add-on of a polymer as it dictates the strength and elongation belongingss of the movie produced1 and accordingly the ability of the movie to defy forces applied during fabrication, packaging, storage and handling, 13 nevertheless the movie is still required to retain an acceptable decomposition clip when placed in the unwritten cavity.1

Mentioning back to postpone 2-4 it can be seen that the concentration of polymer incorporated within a movie is typically between 60-65 % , this is because the polymer will organize the base of the ODF13.

An ideal polymer is required to be non-toxic, non-irritant, easy wetted, have good spreadability and cheap to manufacture.3

Normally used polymers include pullulan, Hydroxy propyl methyl cellulose should it be capital C? ( HPMC ) , Hydroxy Propyl Cellulose ( HPC ) and gelatin1.

Polymers that will be utilised in this undertaking include ; Methocel ( HPMC ) E5, Methocel ( HPMC ) E50, Klucel ( HPC ) and Starch. Table 2-5 below shows the belongingss of these polymers.23

Type of Polymer

Property of the Polymer



Stability and safety

Regulatory Status

Methocel E5 and Methocel E50

Odorless, tasteless,

White farinaceous pulverization.

Soluble in cold water/ ethyl alcohol.

Insoluble in hot H2O.

Hygroscopic after drying.

Excessive unwritten ingestion may do a laxative consequence.

GRAS listed and approved for usage in UK.

No specified ADI* .


Odorless, tasteless,

White farinaceous pulverization.

1 in 2.5 parts ethyl alcohol.

1 in 2 parts H2O.

Insoluble in hot H2O.

Hygroscopic after drying.

GRAS listed and approved for usage in UK.

ADI: 1500mg/kg organic structure weight.



Slight Taste

Fine, away white pulverization.

Slightly soluble in cold H2O.

None, nevertheless ingestion of big sums may be harmful.

Approved for usage in UK.

No specified ADI.

Table 2: Properties of Polymers,23 Abbreviations ; ADI: Approved Daily Intake, UK: United Kingdom, GRAS: By and large recognised as safe

The usage of a mixture of polymers improves ODF belongingss such as the hydrophobicity, flexibleness, oral cavity feel and solubility.1 A survey carried out by Kulkarni24 focused on the public presentation of assorted polymer mixes and demonstrated the ability of polymer decompression sicknesss to take down decomposition times of ODFs and better their visual aspect.


Incorporation of plasticizers allows production of flexible ODFs and decrease of crispness caused by the add-on of a polymer.21 Plasticiser molecules work by infixing themselves between polymer molecules, diminishing the attractive force and accordingly diminishing Glass Transition temperature ( Tg ) .1 As seen in table 2-4 the concentration of plasticizers incorporated within the preparation is low, this is because a high concentration consequences in movie snap, skining and splitting, therefore impacting the API soaking up rate.21 An ideal plasticizer is required to be compatible with the polymer and dissolver included within the formulation.13 Furthermore some surveies besides show that APIs incorporated may besides copy the activity of a plasticizer, therefore increasing the rate of dissolution.1 The major ruin associated with plasticizer usage may impact the rate of absoprtion of the drug.13

Common plasticizers include Polyethylene Glycol ( PEG ) 400 and glycerin. Plasticiser utilised within this undertaking is PEG 400, belongingss of PEG 400 can be seen in table 2-6 below.23





Stability and safety

Regulatory Status


Clear, syrupy liquid,

Slight odour,

Slight acrimonious gustatory sensation.

Soluble in H2O.

Excessive unwritten ingestion can hold a laxative consequence

Approved for usage in UK.

ADI: 10mg/kg organic structure weight

Table 2: Properties of Plasticisers. 23 Abbreviations ; PEG: Polyethylene ethanediol, UK: United Kingdom, ADI: Approved day-to-day consumption.

The active pharmaceutical ingredient

Prior to API incorporation the belongingss of the drug on the unwritten pit, i.e. gustatory sensation, mucosal irritancy and inauspicious effects such as staining of the dentition, need to be considered.3 Furthermore other factors that require thought include drug compatibility with other excipients and stableness within pH of the mouth.1,3

Table 2-7 shows illustrations of some drugs and the dosage that have successfully been incorporated into ODFs.1 As seen in table 2-7 there are a broad scope of APIs that may be added to ODFs, the lone restriction to API add-on to ODFs is the concentration. As merely a low concentration can be incorporated, the figure of possible drug campaigners limited.13


Curative Class



Nitroglycerin Dervivatives






Smoking Cessation


Anti Migrane



Anti inflammatory

Muscle relaxant

1.0 – 15.0mg

0.3 – 0.6mg


5 – 10mg


12.5 – 25.0mg


Table 2: List of pharmaceutical drugs that possibly incorporated into ODFs9. Abbreviations ; milligrams: miligram

This undertaking involves the preparation of ODFs incorporating ethyl aminobenzoate as the API, its pharmacological activity and preparation considerations are discussed in item in chapter 3.

Other excipients

Other excipients are included within the preparation to better movie belongingss such as visual aspect, gustatory sensation and decomposition clip. Sweetenings such as sorbitol1 and flavorer agents for case Mentha piperita oil14 are for heightening spirit, saliva exciting agents e.g. citric acid13 are incorporated to increase the production of saliva.13 Other excipients include stabilising agents, inspissating agents and coloring agents ( Table 2-7 ) .21,23





Stability and safety

Regulatory Status


White solid


Sweet tasting.

Soluble in H2O.

Partially soluble in ethyl alcohol.


GRAS listed.

Approved for usage in UK.


White solid.


Sweet gustatory sensation.

1 in 25 parts ethyl alcohol.

1 in 0.5 parts H2O


GRAS listed.

Approved for usage in UK.

Sodium Sachharin

White solid.


Sweet gustatory sensation.

1 in 50 parts ethyl alcohol

1 in 1.2 parts H2O.


Approved for usage in UK.

ADI set by WHO: 2.5mg/kg.

ADI set by COT: 5mg/kg

Citric Acid

White crystals.


Strong acidic gustatory sensation.

1 in 1.5 parts ethyl alcohol.

1 in & lt ; 1 parts H2O.


GRAS listed.

Approved for usage in UK.

Table 2: Properties of other excipients incorporated in to ODF23, Abbreviations ; WHO: World Health Organisation, COT: Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment, GRAS: Genreally recognised as safe.


There are several methods that may be utilised for the casting of the preparation, which can be found in assorted beginnings of literature such as those discussed by Dixit1 and Arya11. The two common methods are Solvent casting and the hot thaw bulge method.1,11

Table 6 high spots the chief differences between the dissolver casting and the hot thaw bulge methods of manufacture.25

Solvent Casting Method

Hot Melt Extrustion Method

API may be thermoliable

Solvent incorporation is necessary

High possibility of incorporating air bubbles

Water is incorporated as a dissolver

Rollers and coaters are required for big graduated table production

API incorporated must be thermostable

No dissolver is required

Incorporation of air bubbles in low.

Water incorporation is non necessary

Hot thaw extruder is required for big graduated table production

Table 2: Major differences in the dissolver projecting method and hot thaw bulge method of industry of ODFs.25 Abbreviations ; API: Active pharmaceutical ingredient

The method of industry that will be used in this undertaking is the solvent casting method. This method involves blending all H2O soluble excipeints with H2O a homogenous solution, staying excipients are so added consecutively until a homogenous mix is produced. The mixture is so degassed to take air and dramatis personae for drying.13 The benefit of this method is that it does non needfully necessitate exposure to heat for the drying procedure hence can be used for thermoliable APIs.1


Once an ODF has been manufactured it is tested against Pharmacopoial and mark criterions to guarantee the merchandise is ready for the market. This includes look intoing the merchandise has been manufactured as predicted and the movie produced meets the quality standards. There are a broad scope of trials that can be carried out on the ODFs produced and these are good referenced.1,3,9,11,13,14,20,27

The trials that will be carried out in this undertaking include:


It is of import to prove the thickness of a peculiar strip as it indicates the uniformity of the drug content and therefore shows how successful the procedure of fabricating was.1 The thickness can be measured utilizing a micron ( I?m ) screw gage at about 5 different locations on the movie strips manufactured and the average thickness is so calculated.21

Folding endurance

The strip is folded repeatedly in the same topographic point until it breaks.1 The figure of times the movie can be folded before a tear appears is the endurance value. The principle of this trial is to analyze the movies capacity when repeatedly folded, therefore finding its physical strength.27

Decomposition clip

The decomposition clip looks at how fast the strip will fade out when placed in a little volume of H2O, therefore enabling analysis of the clip the ODF will take to disintegrate when placed in the mouth.1 The bound for ODTs harmonizing to pharmacopoeial specifications is normally 30s or less,26 nevertheless since ODF specification are non yet established tablet criterions will be used.

Contented uniformity trials

This method involves the usage of UV analysis to find the API content within each strip and hence evaluate on movie uniformity. 13 To make this a standard analysis will be done for the API and compared to the analysis CHECK PHARMACOPOIEA. Pharmacopeial specifications estimate the uniformity of the drug within any preparation to be normally within 85-115 % .1,26

Uniformity of weight

3 strips from each batch will be separately weighed and an mean deliberate. These weights should non divert excessively much from each others as high divergence indicates hapless mix. Together with the content uniformity trial it enables analysis of homogeneousness of the film.27