ROUTES: PARENTERAL

ROUTES: PARENTERAL

1. Any route other than oral, sublingual, buccal or rectal is considered a parenteral route

2. The term parenteral means next to, or beside, the enteral. It refers to any sites of administration that are outside of or beside the alimentary tract

3. Intraocular

   • Volume of tears: 7 microliters
   • Hold up to 10 microliters without spillage
   • Eyedropper dispenses 50 microliters hich means 80% of a dose will be lost from the eye overflow
   • Rate of tear production: 2 microliters/minute
   • Tear volume in the eye turns over every 2-3 minutes
   • Ophthalmic ointment tubes hold approximately 3.5 g of ointment

4. Intranasal

   • Nasal cavity capacity: 20ml
   • Most common use is for decongestant activity
   • Should not be used for prolonged periods

5. Inhalation

   • Metered dose inhaler (MDI)
     • Delivers a fixed dose when the aerosol is actuated
   • Adapter and Spacers
     • Allows the patient to coordinate inhalation and actuation of the aerosol
   • Dry powder inahler
     • Device automatically releases the drug when the user inhales
     • The powdered drug is supplied in hard gelatin capsules, cartridges, or foil blister strips, and is loaded into the inhalation device
   • Atomizers and Nebulizers
     • Device breaks up a liquid into a spray

6. Dermal

   • Most dermal dosage forms are used for local effects on or within the skin
   • Ointments, creams, and lotions are the most popular dermal formulations
   • Collodions: liquid preparations of proxylin dissolved in a solvent mixture of alcohol and ether. Looks like raw cotton and is slowly but completely soluble in the solvent mixture. When applied to the skin, the solvent rapidly evaporates, leaving a protective film on the skin that contains a thin layer of the drug
   • Liniments: alcoholic or oleaginous solutions generally applied by rubbing
   • Dermal aerosols are generally used to apply anesthetic and antibiotic drugs for local effect

7. Vaginal

   • Avoids degradation that occurs with oral administration; doses can be retrieved if necessary; and it has the potential of providing long term drug absorption
   • Suppositories are used as contraceptives, feminine hygiene antiseptics, bacterial antibiotics, or to restore the vaginal mucoas

8. Parenteral routes are some times preferred when a rapid drug response is desired, as in an emergency, or when the patient is uncooperative, unconscious, or otherwise unable to take a drug by an enteral route

9. Disadvantages

   • Cost more than enteral route
   • Require skilled personnel to administer them
   • Once administered, it is most difficult to remove the dose if there is an adverse or toxic reaction

10. Injections

    • Intravenous
      • Needle gauge: 16-20
        • Large needle gauge
      • Needle length 1-1.5"
      • May be large volume, slow infusion
    • Intramuscular
      • Needle gauge: 19-22
      • Needle length: 1-1.5"
      • Slower onset but longer duration of action compared to IV
      • Z-tract injection
    • Intradermal
      • Needle gauge: 25-26
        • Small needle gauge
      • Needle length: 3/2"
      • Injected into the top layer of skin at a slight angle
    • Subcutaneous
      • Provides slower absorption compared to IM, but faster absorption compared to oral administration
      • Prefferred route of administration for implants
      • Needle gauge: 24-27
      • Needle length: 3/8 - 1"