Drug Sources, Products & Routes

• The text discusses the sources of drugs, drug products, routes of drug administration, and pharmacokinetics.

Sources of Drugs

• Drugs can be synthetic (e.g., omeprazole, sulfonamides).
• Drugs can be obtained from cell cultures (e.g., alglucerase).
• Drugs can be produced by recombinant technology (e.g., human insulin, tissue plasminogen activator).
• Some drugs are obtained by hybridoma technique (e.g., monoclonal antibodies like rituximab).

Drug Products

• Drug products are grouped by physical and chemical properties.
• Acids react with bases to form salts.
• Alkaloids are basic substances that form salts with acids.
• Glycosides are combinations of sugars with organic substances.
• Volatile oils are obtained from plants by distillation and used as flavoring agents, carminatives, and antiseptics.
• Fixed oils are glycerides obtained from seeds, used in cooking, and have food value.
• Mineral oils are mixtures of hydrocarbons obtained from petroleum, used as laxatives or ointment bases.
• Tannins are non-nitrogenous astringents.
• Resins are solids insoluble in water but soluble in alcohol.
• Gums are polysaccharides secreted from tree bark and used as emulsifying agents.

Routes of Drug Administration

• Drug routes are categorized as enteral, parenteral, and local/topical.
• Choice of route depends on drug properties and patient requirements.

Enteral Route (Oral Ingestion)

• Oral route is common, old, and safe.
• The large surface area of the gastrointestinal tract, content mixing, and pH differences facilitate drug absorption.
• Acids, enzymes, and bacterial flora in the gut can destroy some drugs.

Advantages of Oral Route

• Safest, most convenient, and most economical.
• Drugs can be self-administered.
• It's a non-invasive route.

Disadvantages of Oral Route

• Slow action onset makes it unsuitable for emergencies.
• Irritant and unpalatable drugs cannot be administered.
• Poor absorption can occur due to drug properties, e.g., streptomycin is poorly absorbed orally.
• GI irritation may lead to vomiting.
• Unpredictable absorption may occur.
• Some drugs are destroyed by gastric juices (e.g., insulin).
• Unsuitable for unconscious or uncooperative patients.
• First-pass effect can occur.

Overcoming Disadvantages of Oral Route

• Irritant drugs can be given in capsules.
• Bitter drugs can be sugar-coated.
• Drugs can be coated to make them more acceptable.

Enteric-Coated Tablets

• These tablets are coated with substances undigested by gastric acid but disintegrated in alkaline intestinal juices.
• The polymer choice and coating thickness influence dissolution.
• Designed to prevent gastric irritation.
• Designed to avoid the destruction of the drug by the stomach.
• Designed to provide higher drug concentration in the small intestine.
• Designed to retard absorption, prolonging action.
• If coating is inappropriate, the tablet may be expelled unabsorbed.

Controlled-Release Preparations

• These preparations prolong absorption and duration of action.
• Useful for short-acting drugs.
• Newer formulations coat the tablet with a semipermeable membrane.

Advantages of Controlled-Release

• Reduced frequency of administration.
• Maintain therapeutic concentrations.

Disadvantages of Controlled-Release

• Possible failure of the preparation, leading to toxicity.
• More expensive.

Precautions for Oral Administration

• Capsules and tablets should be swallowed with water in an upright position.
• Recumbent patients shouldn't be given oral drugs due to the risk of esophageal damage.

Other Enteral Routes

• Sublingual and rectal administration are also considered enteral routes.

Parenteral Route

• Parenteral routes are routes other than enteral (intestinal).
• Drugs are delivered directly into tissues or blood.

Advantages of Parenteral Route

• More rapid and predictable action than oral.
• Can be used in unconscious or uncooperative patients.
• Gastric irritants can be given parenterally, avoiding GI irritation.
• Can be used in patients with vomiting or difficulty swallowing.
• Avoids digestion and first-pass metabolism.

Disadvantages of Parenteral Route

• Requires asepsis.
• May be painful.
• More expensive, less safe, and inconvenient.
• Risk of injury to nerves and other tissues.

Parenteral Routes

• Injections, inhalation, transdermal, and transmucosal routes.

Injections

• Injections use a syringe and needle.

Intradermal Injections

• Drug is injected into skin layers, raising a bleb.
• Used for BCG vaccine, allergy tests.
• Administered by multiple punctures through a drug droplet.
• Only small quantities administered; may be painful.

Subcutaneous Injections

• Drug deposited in SC tissue, e.g., insulin, heparin.
• Slower absorption makes drugs long-acting.
• Patients can be trained for self-administration.
• Absorption is enhanced by hyaluronidase.

Disadvantages of SC Injections

• Irritant drugs cannot be injected due to pain from nerve supply.
• Absorption unreliable in shock due to vasoconstriction.
• Repeated injections can cause lipoatrophy.

Subcutaneous Administration Methods

• Dermojet: Uses high-velocity drug jet projected from a gun.
• Pellet implantation: Uses small drug-packed pellets for sustained release.
• Sialistic implants: Drug packed in tubes for months-long absorption.

Intramuscular Injections

• Aqueous solution injected into skeletal muscles.
• Absorption occurs by simple diffusion; larger molecules via lymphatic channels.
• Absorption is rapid.
• The volume of injection should not exceed 10 ml.
• For infants, rectus femoris is used instead of gluteus.
• Oily solutions or suspensions result in slow, steady absorption.

Advantages of IM Injections

• Reliable intramuscular route.
• Rapid intramuscular absorption.

Disadvantages of IM Injections

• May be painful.
• May lead to abscess formation or tissue necrosis.
• Nerve injury is possible; avoid injecting irritant solutions near nerves.
• Absorption slower than oral for some drugs (e.g., diazepam, phenytoin).
• IM route should be avoided for some drugs, e.g., heparin, calcium gluconate.

Intravenous Injections

• Drug injected into a superficial vein.
• Directly reaches circulation, immediately available for action.
• Administered as bolus, slow injection, or slow infusion.

Advantages of IV Route

• Most useful in emergencies.
• Provides predictable blood concentrations.
• Can administer large solution volumes.
• Can administer irritants safely due to dilution.
• Allows rapid dose adjustments.

Disadvantages of IV Route

• Cannot withdraw drug once injected.
• Extravasation may cause irritation.
• Only aqueous solutions can be given.
• Self-medication is difficult.
• Risk of embolism.

Other Injection Routes

• Intraperitoneal: Used for fluids in infants and for peritoneal dialysis.
• Intrathecal: Injected into subarachnoid space for CNS action, needs aseptic precautions.
• Intra-articular: Injected directly into a joint for treatment. Needs strict aseptic precautions.
• Intra-arterial: Injected directly into arteries for peripheral vascular diseases, diagnostics.
• Intramedullary: Injection into bone marrow, rarely used.

Inhalation

• Lungs have a large surface area for absorption.
• Volatile liquids and gases are given by inhalation, e.g., general anesthetics.
• Solutions of drugs can be aerosolized; inhaled drugs/vapors act locally or are absorbed.
• Drug delivery influenced by particle size, breathing pattern.
• Available as metered dose inhalers (MDI), dry powder inhalers (DPI), nebulizers.

Advantages of Metered Dose Inhalers

• Almost instantaneous absorption due to large surface area, thin membrane, high vascularity.
• Serves local route in pulmonary diseases.
• Direct delivery, smaller dose needed, reduced toxicity.
• Hepatic first pass metabolism is avoided,

Disadvantages of Metered Dose Inhalers

• Irritant gases may enhance pulmonary secretion.
• Drug particles may induce cough.
• This is an important route of entry of certain drugs of abuse.

Transdermal

• Lipid-soluble drugs applied for slow, prolonged absorption, e.g., nitroglycerin. -Adhesive units, inunction, iontophoresis are forms of transdermal delivery.

Transdermal Adhesive Unis

• Adhesive patches held between polymer layer and porous membrane The drug diffuses with percutaneous absorption.
• Rate of absorption is constant and predictable.

Suitable Transdermal Patches

• Potent drugs and short-acting drugs
• Applications in chest , abdomen ,arms or back; scrotal for testosterone. Examples are:
• Hyocine, nitrocliserin, testosterone, nicotine and fentanyl.

Advantages of Transdermal Patches

• Prolonged duration and constant plasma drug levels due to good patient compliance.

Disadvantages of Transdermal Patches

• Large does limited, irritation, expensive.

Inunction

• Rubbing the skin to get absorbed and produce systemic effects.

Iontophoresis

• Galvanic currents enhance the permeability of the skin penetration of lipid insoluble drug-hypersensitivity.

Jet Injection

• The skin dermojet may be form of dermal drug amdinstration.

Transmucosal

Transmucosal drug amdinstration absorbs in the blood streams.

Sublingual

• Tab or pellet drugs place below tongue. It is absorbed through the mucousa: Nitroliserine, nifedipine,buprenorphile. tab can crush.The saliva quick absorption.

Advantages of Subligual,

It rapid with inminustes drus reach. Because reach systemic no metabolism will occur.If too much drug is undesired spew it out.

Disadvantages

• Buccal ucleraition cuase higer waeight avoid the highroute

Nasal

• Nosal adminster for system and local use . Spray for otc spray nose for allergic rintis local

Rectal

Rectal reach supply and drugs can reach rectus syetmic, superior haemrrholdial vein, no past pass. Indomenctahim choromazin can givin rectally. Gastric irrtatiton ,Geritatic or ucnosucuss all help

Disadvantages

• Ittatoin may irregulat. Enermna use to help empty bowel

Topical

• Local use: cream etc.
• eye for mucusa membrames

Special Drrug Delivery

This provide drus better. it improve drug dalivary , the actoi and compolace . to the sies so acint require partivulaer antycer.

• oucurster, trasndremal and eliting

Oscuret

• This thin contain reservoir and releaser sllwoly . pilcoarpune used 7 dys

Progrestersert

It deliverd proestgenon for long time ovwe rone year

Prorug

It inacitive, but cange ti form.

• imprivive toxicilt and stabil.

Osmic pup and compuerz pup

This will contant release the drug rate insulin pulse from GnRH,

Drug Delivet

Lipspome: Phosolipds Monocolons antiobdes: turnoe cells naooparticd: cncapilsed drugs, POlyemer baedl: Transder amal drus eluteing : Stens

Pharmokinetics

• The drugs must go in and out of body
• Absorption
• Distribution
• Metabolism
• Excretion
• and how the drug will reapond
• Then is barriors cells like the instine, blood cels

cell Mebrane

• The biooical mentran made fo the two layre of philpphids dissolve.

Procces of passing

• diffiussion throwh lidpid hrough aquus porues by acrriuer

Membrane Trnaposrt

• The juncts between the epelthelial clal or the cell have pore. and move some subatcnes

_ Active tranport

• transfer the duss against the transpost. This for nature _ Diffusiosn faiclatiated diffusiosn. The unique form for the active which occures form in energy ,It highly specific . ex guacse and vitamin

Endcytis

• Thius proce for small to be cell vessles

Absoption

The adminiattiosn for the circltaiton a reahc sits, must though membeain or 1 process, passiv and medieadtr .

• ecept for intraverus . The raete.
• aborption form het gut; from buccal cabivtily.Acifrugs the stomach; while basic drugs are not abospe.
• Iitnetne. This has the large surface area the jojunum. Basic dgsr are abspe because of hte provable

Fatcors infludece Absortopn

• Diigration the should oreak orrall FORMUA: the prepared the absop
• Particles sizes: small are importatn
  lipid solbility [H Ph. and ioinzartuons Surface and Abspe Gaatrinster motility. if gastric ermpit

First PAsee MEtbaoliss .It is is the ket baox 1 the metaolam of durbgs Doses may increse Absopr:On intrvenous tbe drh shol shol dissolve It is fater.Lidi ps are abospe Inthe lungs re allpslve _ Thes imporant pulmaniry

Biovablity

The aministering and the rech in change from the systmic. Bivoaltlity. I is the fraction of the drug the reach or the Bivoelacule It is the facte that imporant

Biocolse

The conmpare to the effecitntees I he rate og absorpitpn

Distrubiton

I is reach to orfans it should cross seveal barriors. There is lipid osolbtiy, blood flow and the bindning plamsa. The linonzesf the drugrwidely thru out

Plamsa protiens

This reach form. Bindng to the alumbions a and the drug and only form alviblityo. It affect by the factosr.

• Redustrubiton is when the lipid drugs use in the veinns
• Bloobd brain Barrior It is lock intercellus and it can only lipid solve drug can cross this bbbr

Placenal Barriors

This the cell wall adn thos wot be in fessits

Vouloume

It conatin volume body Appearent: It is the amont Important: If the drug rretin i the plasma hte vloume ss aml. Lipid will be large Knowledge Vd The know

Brotansfor

It alets how the drus go to the body and treat them from the xenobities. The proceses conver the durfs to polar form thru the lungs kidneys skin liver

Sies

Tranfom is the aciton If the drug may acite . Transfrom ma yactiue