Advantages and Disadvantages of Different routes of administration
SC Advantage
Absorption is slow but complete. This route is improved by massage or heat. Vasconstrictor may be added to decrease absorption of a anesthetic agent , therefore prolonging its effect at the site of interest
IV ROUTE Disadvantage
Can't reverse a toxic dose, requires specialized personel. May be expensive
Rectal Advantages
By passes liver . It has a reduced first pass effect . This route is useful if patients cant take drugs orally or with young children ( example aspirin, theophylline, chloropromazine and some barbiturates )
Oral Advantages
Convenient ( storage, portability, pre measured dose), economical, non invasive often safer route, requires no special training
Rectal Disadvantages
Erratic absorption-
Buccal / Sublingual Disadvantages
Holding the dose in the mouth is an inconvenience . If any of the drug is swallowed it will then be subject to the fpe
Buccal/ Sublingual Advantages
In this route of administration the liver is bypassed , and bioavailability is higher. This type of administration has rapid absorption
Inhalation
Local effect - bronchodialators Systemic Effect- general anesthesia This type of administration is rapidly absorbed, if it is absorption of gases. solids and gases are excluded if larger than 20 microns and only 10 % of the dose will be absorbed
Topical
Local effects- eyes drops, antiseptic , sunscreen . Used for callous removal
Forms of Pulmonary Delivery
Nebulizer, Dry Powder Inhalers, MDI
Pulmonary Disadvantages
Takes significant degree of coordination. Patients with lung disease may be able to inhale adequately variability in delivery
Factors that influence ocular drug retention
Technique of Application, Drop Size, Formulation (tonicity, viscosity), pH of solution
Parenteral
The routes of administration dont deal with the GI tract. IV, SC, IM
SC Disadvantage
This route may be painful , irritant drugs can cause local tissue damage. Small doses limit use
Intramuscular Disadvantages
Trained personal , the sight of injection will influence the absorption. Absorption is erratic , especially for poorly soluble drugs (diazepam and phenytoin ). The solvent may be absorbed faster than the drug causing precipitation)
IV ROUTE ADVANTAGE
You can deliver drugs in large amounts, you will have 100 percent bioavailability.
Pharmacological agents administered through inhalation for local effects
beclomethasone, terbutaline, cromolyn, metaproterenol, albuterol, pirbuterol
Oral Disadvantages
drug delivery is usually incomplete. Highly dependent on patient compliance .Increased drug- drug, and drug- food interactions . Drugs are exposed to first pass effect
Pulmonary Advantages
easy to titrate dose, rapid onset for local effect, maximize benefit, minimize side effects
Intra arterial
for cancer chemotherapy to maximize drug concentration at the tumor site
Intranasal
has some systemic effects with propanolol
Nasal route
historically used for local effects, their are a growing number of compounds used intranasal that are intended for systemic effects. Used in patients that require drugs to be absorbed but cant use the GI TRACT. (Examples anticonvulsants (midazolam), narcotic antagonists (naloxone), peptides (calcitonin, insulin), and smoking cessation agents (nicotine)
Intramuscular Advantages
larger volume than sc, can be given by IM . A depot or sustained release effect is possible with IM injections ( procaine and penicillin)
Pharmacological agents administered through inhalation for systemic effects
pentamidine, halothane, ergotamine, methoxyflurane, enflurane, isoflurane, nitrous oxide
Enteral
the routes of administration deal with the GI tract. Oral, Rectal , Buccal