<prompt> Nitroglycerin is effective as sublingual medication because it is:Ionic and lipid solubleIonic and less lipid solubleNonionic and highly lipid solubleNonionic and less lipid soluble  <response>: Ans. c. Non-ionic and highly lipid soluble Ref: Goodman Gillman 12e p22: KDT e p6Nitroglycerine is effective as sublingual medication because it is non-ionic and highly lipid soluble.Sublingual Administration. Absorption from the oral mucosa has special significance for certain drags despite the fact that the surface area available is small. Venous drainage from the mouth is to the superior vena cava, bypassing the portal circulation and thereby protecting the drug from rapid intestinal and hepatic first-pass metabolism. For example, nitroglycerin is effective when retained sublingually because it is non-ionic and has very high lipid solubility. Thus, the drug is absorbed very rapidly. Nitroglycerin also is very potent: absorption of a relatively small amount produces the therapeutic effect. --Goodman Gillman 12e p22Systemic Routes of Drug Administration1. Oral Most common most convenient2. Sublingual Avoid first pass metabolism, used in emergencies Drug should be nonionic having very high lipid solubilityQ Example: Nitroglycerine, Isosorbide dinitrate Nifedipine3. Rectal Drug is absorbed into external hemorrhoidal veins, bypasses liver, but not that absorbed into internal hemorrhoidal veins. First pass metabolism occurs, but less than oral route Avoid first pass metabolism by 50 Example: Diazepam in children for febrile seizures4. Cutaneous Transdermal for highly lipid soluble drugs Example: Nitroglycerine. Nicotine, Hyoscine, Fentanyl Estrogen5. inhalational Drug delivery can be controlled like IV infusion Drugs used in asthma: Salbutamol, Ipratropium, Monteleukast, Inhalational steroids Inhalational anesthetics6. Nasal Example: Nafarelin GnRH agonist, Calcitonin, Desmopressin, Influenza vaccine7. ParenteralIntravenous Emergency use, increased risk of adverse effect, not suitable of oily solutions, or poorly soluble substance best for steady state plasma concentration.Subcutaneous Suitable for some poorly soluble suspensions, appropriate for self administration Example: InsulinIntradermal The drug is injected into skin raising a bleb e.g. BCG vaccine, sensitivity testing. It produces local tissue necrosis and irritationIntramuscular Suitable for oily solutions and some irritating substancesNanotherapyNanotherapy: Novel method for drug deliveryNanoparticles are offering new opportunities for diagnosis, targeted drug delivery and imaging of clinical effect 