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Pharm dispensing (Route of drug administration (Considerations (Solubility…

- - - - Internal use
        
        Pastilles: solid medicated preparations containing glycerol, gelatin, acacia and high % of sucrose. To be dissolved slowly in mouth for prolonged action and generally used for cough relief/sore throat.
        
        Capsules
        
        Hard gelatin shells: made of gelatin, water and sugar and cylindrical in shape with hemispherical ends. Cap and body locked after filling of drug (usually in solid form) eg amoxicillin. Comes in different sizes (with inert bulking agent eg starch and kaolin): 000 (1000mg), 00 (600mg), 0 (500mg), 1 (300mg), 2 (250mg), 3 (200mg), 4 (150mg) and 5 (100mg)
        
        Softgel: made up of gelatin, water, sugar and plasticisers - increase flexibility (eg sorbitol and glycerol) and hermetically sealed capsules with variety of shapes. Drugs may be in liquid or semi-solid forms, to protect drugs from oxidation. May be swallowed whole and some may be opened to mix with drinks for swallowing difficulties.
        
        Medicinal agents with or without excipients enclosed in gelatin(derived from partial hydrolysis of collagen from skin, connective tissues and bones from animals) shell. Readily soluble in water at room temp and to be swallowed whole (but can be opened for patients with difficulty swallowing). Sensitive to heat and humidity (softening of gel), may not be suitable for certain groups eg Muslims, vegetarians (gelatin made from animals) and more costly than drugs in liquid form
        *Readily mask unpleasant taste and easy to swallow. Lesser excipients needed compared to tablets. Rapid and uniform drug release. Able to protect light-sensitive drugs by opacifying shells (made from TiO2)
        
        Lozenges: hard, flavoured base and drug slowly released as it dissolves slowly in mouth. May contain antiseptic (2,4-dichlorobenzyl alcohol) or anaesthetic (benzyldamine hydrochloride) and can be used for local or systemic effect. Available in sugar-free formulation
        
        Tablets
        
        Medicaments with one or more excipients and comes in variety of shapes, colours and sizes (for ease of differentiation). Prepared mainly by compression (compacting the drug in powdered or granulated form - less likely to stick to punch in machine) and sometimes moulding. Designed to be swallowed whole which then disintegrate in GI tract for release.
        
        Chewable tablets: chewed before swallowing. Usually disintegrate rapidly and contains mannitol (sweet and exerts cooling effect to mask unpleasant taste). Used for elderly patients and young children with difficulty swallowing.
        
        Effervescence tablets: granular effervescent salts release CO2 gas upon contact with water and rapidly dissolves.
        
        Sublingual tablets: placed under tongue for dissolution or disintegration. Used for drugs with large first pass effect eg Glyceryl Trinitrate used for angina attacks.
        
        Enteric-coated tablets: delayed-release features (delayed drug release until alkaline conditions) eg aspirin (irritate stomach lining)
        
        Sustained-release/long-acting/extended release/controlled release tablets: promote continuous, sustained drug release. Contains significantly higher drug conc than normal release ones. Reduces frequency of administration (frequency of drug consumption) and this improve drug adherence (patient follows dosing regimen). Tablets to be swallowed whole.
      - External use
        
        Pessaries: for vaginal use and can be ovoid, globular or cone-shaped. Usually used with bases eg macrogol and glycerol gelatin and contains medicaments eg contraceptives for localised effects. Theobroma oil only used in topical forms eg for anti-fungal use.
        
        Powders: mixture of two or more insoluble solid preparations in finely powdered form and used externally (not on open wounds) eg chalk, bismuth salts, zinc. Increase absorption rate through high SA (finely divided)
        
        Suppositories: solid dosage forms for insertion into rectum where it melts, dissolves or disperse. Usually cylindrical shape with tapered end and contains drug, base and other additives. Can be used for local (constipation relief eg glycerin, inflammation eg hydrocortisone) or systemic (nausea eg prochloperazine) or fever/pain relief eg paracetamol, diclofenac) may have some social stigma, inconvenient administration, may cause leakage problems and there is variable absorption due to fecal matter present
        Used with patients who are unconscious, swallowing difficulties (eg babies) or GI problems eg nausea
        
        Enema: Bases similar to suppositories but can exist as solutions or suspensions. Usually used for anti inflammatory, anthelmintic (anti-parasitic), purgative, sedative effect or for x-ray examination of the large gut e.g. pregnisolone
    - - Oral solutions: active ingredients dissolved in suitable solvent/mixture of miscible solvents
        Allows for rapid absorption, easy to swallow, uniform drug distribution per dose and good for elderly/kids
        medicaments are less metabolically stable than in dry forms, difficult to mask unpleasant flavours, bulky and measurement of dose depends on accuracy of patient
        
        Internal use
        
        Linctures: viscous liquids usually used in cough treatments and contains high conc of syrup or polyhedric alcohol eg glycerol and to be sipped slowly without dilution of water for prolonged local action (demulcent effect - thin coat on throat to soothe and reduce pain & inflammation) eg promethazine and codein linctus
        
        Elixirs: clear, pleasantly flavoured liquids containing syrup and high ethanol conc and other solvents (eg glycerol) with antimicrobial & flavoring agents. Usually contain potent drugs like antibiotics, antihistamines & sedatives and 10-12% ethanol are self-preserving eg diphenhydramine HCl elixir
        usually not given to children due to lower conc of syrup & higher alcohol content
        
        Syrups: conc aq solutions containing sugar with or without medicinal properties (eg sucrose/sorbitol) and frequently flavoured to mask disagreeable tastes of drug eg Syrup BP, sodium valporate/epilim syrup (for epilepsy)
        longer shelf life for aq. solutions (>65% sugar conc) as sugar acts as preservative (low water potential) and sorbitol (sucrose analog) used in sugar-free drug
        
        Mixtures: simple liquid preparations containing only dissolved medicaments. May be homogenous solution or heterogenous suspensions eg potassium iodide & ammonia mixture (expectorant oral solution) or kaolin & morphine mixture (laxative)
        
        Tips for dispensing: plain, smooth amber/plastic bottle with black cap and for linctuses (sip & swallow slowly without addition of water)
        
        External use
        
        Mouthwashes: aq solution in concentrated form with antiseptic/local analgesic properties or used to clean & refresh oral cavity eg chlorhexidine mouthwash
        
        Gargles: relieve soreness in mild throat infections and contain antiseptics, analgesic & astringents (reduce mucus in throat) and contain higher conc of active ingredients compared to mouthwash. Usually used with "swish, swirl and spit" to bring medicaments to mucous surface n throat eg phenol gargle or Difflam-C
        
        inhalation: liquid preparations containing volatile substances and usually added to hot (presence of steam) but not boiling water (scald respiratory tract) and vapour inhaled for 5-10 mins eg menthol & eucalyptus inhalation
        **use of light MgCo3 as excipient to provide surface for volatile oil particles to adsorb onto for even distribution & dose
        
        ear drops/otic/aural preparations: solutions of medicaments in water, glycerol, propylene glycol or diluted alcohol and used to soften wax, treat local inflammation and infection for pain relief
        propylene glycol should not be used if eardrum is perforated as it may cause deafness
        
        nasal solution drops & sprays: drugs for instillation in nasal passage via dropper or from metered spray device and usually made isotonic (0.9% normal saline) and buffered to normal pH range of nasal fluids (pH 5.5-6.5). Drugs usually potent (low bioavailability) Viscosity of liquid adjusted using cellulose derivatives eg methylcellulose. Used as decongestant for common cold & local steroids for allergic rhinitis or for systemic effects eg miacalcic nasal spray (synthetic salmon calcitonin) to regulate Ca2+ conc or to deliver drugs to brain
        
        eye drops: solutions with/without active medicaments for instillation into eye and is sterile and isotonic with lachrymal fluid (0.9& w/v NaCl).
        
        lotions: liquid preparations for application to unbroken skin without friction (solutions, suspensions & emulsions) and may contain aq, alcoholic or emulsified bases and either dabbed on skin or applied with non-evaporative dressing. can be applied on hairy regions and on skin regions with acne and useful for applications over large areas
        
        Tips for dispensing: 1) gargles & mouthwash usually contain humectant (active ingredient eg glycerol with high conc. of OH grps to attract water and keep area moist) and usually labelled "not to be swallowed in large amounts" and include directions for dilution. Stored in fluted (grooves on sides of bottle), oval amber bottle; 2) inhalations: stored in amber, fluted glass bottle and labelled "not to be taken"; 3) nasal and ear drops: stored in amber, ribbed hexagonal glass bottles fitted with a teat and dropper and should be labelled "not to be taken" and not shared; 4) Eye drops: stored in 10ml amber, hexagonal ribbed glass bottle with dropper tube and labelled "not to be taken" and "for use in the eye only"; 5) lotions: stored in amber, fluted glass bottle and labelled "for external use only" and "shake the bottle before use" (if applicable)
        label must not be stick on fluted surfaces. To pinch label at end
        
        Liniment: solutions formulated with alcoholic/oily vehicle and contains active ingredients eg camphor, menthol & methyl salicylate that possesses analgesic & rubefacient properties (produce redness on skin due to vasodilation for increased blood flow). Usually rubbed onto unbroken skin to relieve pain/soreness arising from sprains & arthritis
      - Suspensions: coarse dispersion containing finely-divided insoluble drug suspended in liquid medium
        *for patients with difficulty swallowing, for drugs with unpleasant tastes can be made into insoluble derivatives and formulated as a suspension, more rapid absorption compared to solid dosage forms and prolongs release of drugs for IM and SC injections eg benzathine penicillin (IM for syphillis) and protamine (SC for insulin)
        Labelled "shake well before use" and "store in a cool place"
        
        Indiffusible solid suspension: solids that either settle too rapidly for even dosing during withdrawal or do not wet enough to produce uniform smooth suspension and are usually suspended by thickening/suspending agents to increase viscosity eg aspirin, phenacetin, prepared chalk, aromatic chalk powder, barbiturates and sulfonamides
        
        Types of suspending agents:
        
        natural polysaccharide eg tragacanth powder, acacia & sodium alginate
        
        semisynthetic polysaccharide eg methylcellulose, hydroxyethylcellulose
        
        clays eg bentonite (only for external use), magnesium aluminium silicate
        -synthetic thickeners eg carbomer, colloidal SiO2
        
        Diffusible solid suspension: solids readily dispersed in aq. media and remain suspended when shaken for even distribution eg light kaolin light MgCo3 and magnesium trisilicate
      - Emulsion: disperse system consisting of 2 immiscible liquids and disperse phase is finely divided and distributed through continuous phase eg oil-in-water (o/w) or water-in-oil w/o) emulsion
        **emulsions are unstable (require emulsifying agent eg gums (acacia) or synthetic cellulose derivatives (methylcellulose) for agents to be adsorbed at interface of oil & aq phase (surface active/amphiphatic)
        (o/w) proportion: 1) fixed oil (almond oil, arachis oil, castor oil, cod-liver oil) 4 parts oil, 2 parts water and 1 part gum; 2) mineral oil (liquid paraffin) 3 parts oil, 2 parts water and 1 part gum; 3) volatile oil (turpentine, cinnamon oil, peppermint oil) 2 parts oil, 2 parts water and 1 part gum; 4) oleo-resin (male fern extract) 1 part oil, 2 parts water and 1 part gum
        Labelled "shake well before use" and "store in a cool place"
    - - Contraceptive implant: IUD
      - Transdermal patch: Salonpas/medicated patches
      - Sterile dosage forms: eyedrops or IV injections
      - Dry powder & metered dose inhalers: ventolin evohaler or oxeze turbuhaler
      - Chewing gum: nicotine eg nicotex and nicorette (extended release profile)
    - - Ointments: viscous & greasy preparations and base is usually anhydrous & immiscible with skin secretions and used externally on skin or mucuous membranes (emollients), protective preparations or means for local application of medicaments. Usually applied to skin, eye, nasal, vaginal and anus membrane.
        
        emollient & protective ointments (useful for dry skin): contain vegetable oils, synthetic esters of fatty acids or wool fat (anhydrous lanolin) with inert bases (soft paraffin). Occlusive effect (stick on skin surface and not well absorbed) but not easily removed by washing, enhancing penetration and improves efficacy eg on thickened, lichenified skin
        
        water-removable bases (o/w emulsions) and water-soluble bases (PEGs) are easily washed off
        Stored in wide mouth jar/plastic container/collapsible tube
        Labelled "for external use only" and "store in a cool place"
        provides a protective film on the skin and no preservatives required (no water used)
        Not suitable for wet weepy dermatitis, hairy regions, skins prone to folliculitis due to its greasy, sticky and sweat-retention nature
      - Gels: transparent preparation containing cellulose ethers/carbromer in water/water-alcohol mixture and liquify on skin contact and dries off, leaving a thin film of active medication
        useful in hairy regions and cosmetically acceptable (transparent) may irritate skin
      - Creams: for topical use and easier to spread compared to ointments and applied onto unbroken skin. It is in the following forms:
        1) aq cream (o/w emulsion)
        
        easily removed by washing but may be easily contaminated by microbes (require preservative)
        
        may be anionic/cationic (contain the ions in emulgents) and incompatible with each other eg aq cream (anionic) and aq cetrimide cream (cationic)
        2) oily cream (w/o emulsion)
        
        moisturising effect
        
        non-ionic emulgents eg polyoxyethylene esters or ethers and compatible with ionic emulgents eg hydrocortisone
        Labelled "for external use only" and "not to be taken" for nasal, otic, vaginal or rectal use.
        May cause contact allergy due to presence of preservatives. Generally not used for wounds with broken skin as it may cause macreration
      - Pastes: mixture of powder and ointment (eg ZnO 20% paste) and addition of powder improves porosity (breathability) eg when treating diaper rash, a protective ointment base which also allows breathability of the skin is desired.
        Addition of powder to change an ointment into a paste also increases the consistency of the preparation so that it is more difficult to rub off. This property is useful when one does not want an irritating preparation to get onto the normal skin (eg anthralin paste for treating psoriasis)
  - - - Macrogol (type of water-miscible base): mixture of polyethylene glycols (PEGs) and usually made up of 2 PEGs with different Mr: 300, 400, 600, 1000, 1500, 1540, 3350, 4000, 6000 and 8000. (Lower Mr more soluble as hydrocarbon chains shorter). easy to remove from mould, melting point above body temp and no laxative effect
        incompatible with bismuth salts and hygroscopic
      - Glycerol-gelatin (type of water-miscible base): mixture of glycerol, gelatin and water. Does not melt but dissolve slowly in body fluids. Has laxative effect and is hygroscopic
        Long preparation time and difficult to remove from mould, may cause diarrhoea
      - Theobroma oil (type of fatty base): derived from cocoa butter. Melting point range ~ 30 to 36 degrees (body temp), melts readily upon heating and cools rapidly upon settling. Miscible with many solvents and bland (nn-irritating, non-toxic). Contains C=C bonds but exhibit polymorphism during cooling process (over-heating produces alpha and gamma form instead of desired beta form)
        Decrease in melting point in presence of soluble ingredients (impurities) eg phenol and resolved by addition of beeswax. Extra care required during recrystallisation process for higher yield of beta variant. May cause leakage from body and a rancid smell upon storage. It also adheres to mould as it does not contract sufficiently enough during cooling (lubrication needed)
        'Refridgerate. Do not freeze. '
      - Properties of ideal base: 1) readily melts in body temp or dissolves in body fluids; 2) non-toxic and non-irritant; 3) compatible with any medicament; 4) rapid drug release; 5) easily moulded and release from moulds; 6) stable to heating above melting point; 7) resistant to handling (not melting upon hand contact); 8) stable on storage (long shelf life)
      - Synthetic fats (type of fatty base eg fattibase and Wecobee): prepared by hydrogenation of suitable vegetable oils eg palm kernel oil. Solidification points unaffected by overheating, mould lubrication not required due to marked contraction and have better resistance to oxidation (lesser C=C bonds)
        may be brittle if cooled rapidly