Pathophysiology and Pharmacology of common sensory organ disorders.docx

*Pathophysiology and Pharmacology of common sensory organ disorders* ***The eyes*** - The eyes structure: - Sclera: white outer coating of the eyes. Involves posterior and anterior chamber that is seperated by the lens - Cornea: transparent part of the eyes that covers the iris and the...

*Pathophysiology and Pharmacology of common sensory organ disorders* ***The eyes*** - The eyes structure: - Sclera: white outer coating of the eyes. Involves posterior and anterior chamber that is seperated by the lens - Cornea: transparent part of the eyes that covers the iris and the pupil, it enables light to enter the eye. Received nutriton from aquesous humor - Iris: surrounds the pupil and gives the eye its color. Controls quatity of light reaching the lense by dialating and constricting - Retina: covert light into electric signals - Problems associated with the eyes may occur as the result of: - Injuries - Infections - Speceifc eye disorder like glaucoma - Autoimmune disorder - Old age - Drugs used to treat eye infections are called [ophthalmic drugs] they are topical medications in formulations developed specially for the eyes - **Cataracts** - Lens develops cloudy patches and becomes opaque - These patches become bigger with time which causes blurry vision, misty vison and eventually blindness - Usually appears in both eyes (not necessaliry ar the same time) - Usually appears after the age of 70 - Can also affect babies and young children - Symptoms: - Clouded, blurred or dim vision - Sensitivity to light and glare - Seeing halos arounf light - Double vision in a single eye - Development has 4 stages: 1. Immature : lense not totally opaque 2. Mature: lense completely opaque 3. Tumescent: lens filled with water 4. Hypermature: peptides leak through lense capsule - Surgery improves vision in 90% of affected people - Causes of cataract: - Old age - Uveitis: inflammation of the middle layer of the eye - Diabetes and other health problems - Radiation induced: exposure to radtion including sunlight - Traumatic cataract: forming after injury or surgery for other eye problem - Drugs: such as long term use of coricoseteroids - Congential disorders: sometimes hereditary - Rubella during pregnancy caues infants to develop catarct but may not affect vision - **Eye floaters** - Occurs when the vitrous humor startes to shrink with age - Causes stringy masses of vitrous humor that can distrubt light coming into the retina - Tiny shadow is formed into the eyes which makes the floaters noticable - Normal part of the aging process - **Eye inflammation:** - Common symptoms are: redness, odema and itching - Allergyies, infections, tobacco, smoke are common source of inflammation - [Opthalmic antihistamines and mast cell stabalizers] treats underlysing cause - Mast cells stabalizers prevent mast cells from breaking open and releasing histamine and other inflammatory mediators. Mast cell stabilzaers include cromolyn - Some drugs have both characterstucs like optivar - Adverse side effecrs are burning, headache, and stining - [Topical corticosteroids] are very effective - Should not be given to patients with bacterial infection in the eyes because this drug acts as a immunosuppresssant and suppress the immune system - Adverse effect are cataract (when used for a long time), sacondary glaucoma, mydrasis - [Opthalmic decongestanst ] - Gives tempratliry releif to redness and burning of the eye - Example is vasoconstrictos - Adverse effects are minor and include blurred vision, tearning, heachache and rebound vasodilation with redness - **Eye infection:** - Can be caused by bacteria, viruses, and fungus (rarley, but often associated with lense use) - Common eye infections are conjunctivites and blepharitis - requires antibiotic therapy, usually is self limiting and no tretament is necessary until the condition is prolonged or inflratibf it requires [opthalmic antibiotics] - [Anti-infectives] - has the same agent that is used to treat other areas in the body - [antibacterial drops:] chloramphenicol is used for severe opthalmic infections that are unresponsive to other antibiotics. - Others examples: erythromycin, gentamicin, tertracycline - A side effect could be non infectious conjuncitivies and local skin and eye itritation - Before adminsttering, make sure to screen the patient for previous allergic reations - Funal infection can be treated by the common [opthalmic antifungal is natamycin] - **Eye dryness:** - Eye lubricant to replaces tears to allevitae discomfort and is used to moisten contact lenses - [Cyclosporine opthalmic emulsion] relives dry eyes by suppressing the immune response that leads to inflammation, alowing tears to resume - **Conjunctivitis:** - Type of eye inflammation and is inflammation of the conjunctiva (the lining of the eyelids) - Types of conjunctivities is bacterial, allergic, viral, fungal (very rare), chemical 1. [Bacterial conjunctivitis]: - most comon eye conidition requiring antibiotic therapy - Infection caused by staphylococcus auerus, streptococcus pneumoniae, and haemphilus influenzae - Naturally lives on the skin but sometimes enters the eye which leads to redness, irritation, and discharge - High concentration of bacteria overwelms the immunilogiccal capacity of the eye reigon and leads to the infection - [Povidone-iodine opthalmic] solution for treatment - Very broad antimicrobial spectrum and resistence by bacteria is rare - Truns eyes brwon for a few minutes proving that it has been applied - Often used as a preoperative anti-microbial 2. [Viral conjuncitivies] - caused by adenovirus, herpes simplex virus, varicella-zoster virus - Highly contagious, spreads through direct/indirect contact with infected tears or surfaces - Treatment is symptomatic (only affects the symptoms not the underlysing cause) - Symptoms: redness, watery discharge, itching, burning, tearing, gritty feeling, photophobia, swelling - Lasts for 1 to 3 weeks and usually resolves without long term effects - Can be prevented by good hygine, avoid touching eyes, and no sharing towels - Treatmnet is [supportive by using cold compresssers and lubricant], such as chilled artificial tears, for comfort - Severe itching can be treated by [topical vasoconstricntiors and antihistamines ] 3. [Allergic conjuncitivies] - Often the cause of eye inflammation - Similar to viral conjuncitives in apperance but not contagious - Uusally accompanied by nasal congestion, sneezing, and eyelid swelling, with sensitivty to light and sever titcing - Both eyes are affected - **Styes** - Blockage of sebaceous glands at the base of eye lashes - May become infected and require the uese of ocular antibiotics - Usally not painful and is self limiting within 3-4 days - Best way to treat is using [warm compress] several times over 48 hours and If compress are not working then [topical antibiotics] should be used - **Blepharitis:** Inflammation of the edges of the eyelids that is commonly seen in older adults and those with dry eye - **Glaucoma:** - Group of disorders charactarized by an abnormally high intraocular pressure which can damage the optic nerve and other intraocular structures - Anterior chamber is filled with aqueous humor that is secreted by the ciliary body. Excess fluid that is not needed to fill between the lense and iris is drianed througha network. When the drainage is decreases or aqueous humor increase it causes increase in intaocular pressure which cause the disorder - Causes gradual loss of vision and ultimately blindness - Symptoms are gradual loss of peripheral vision, tunnel vision, hazy or blurred vision, severe pain in the orbital and headache, halo around lights, eye redness, patchy vision - Main goal of medications is to prevent damage to the optic nerve by lowering the intraocular pressure 1. [Open angle glaucoma ] - Anterior chamber angle is not normal and remains open with their flow partially obstructed - Most common type which is 90% of the cases - Unknown cause and many patients are asymptomatic until disease has progressed significantly - Usually bilaterlar with eleveated intraoccular pressure develping over years because the trabecular network is blocked and worsens over time - Most cases are treated with medications can be sucessfully treated with medications that works to increase the outflow of aqueous humous at the canal of schlemm and decreases the formation of aqueous humour at the ciliary body 2. [Closed angle gluacoma ] - Very rare and its 5% of the cases, most are adults - Iris bends and blocks the trabecular network by closing the angle where the fluid tipically exist the eye. Drainage of excess aqueous humor cannot be done and it builds up within the eye increasing the intraocular pressure - Management is often surgical and pharma logical management is sometimes effective - [Cholinergic agents :] As the pupil contricts, it straightens the iris, opening and widening the angle to releive closed angle glaucoma - [Osmotics drugs] draws fliud out out of the eye and into the bloodstream - Reduces the volume of vitreous humour which lowers the intraoccular pressure - Mannitol is primarily used in the emergenc treatment because of its ability to rapidly reduce the pressure 3. [Primary Glaucoma] - Occurs due to changes in the eye that happen without cause - Most common type - Chronic and develops slowly overtime 4. [Secondary Glaucoma] - Occurs in response to undelying cause such as injuriym diease, or medication - Can occur gradually or rapidly depending on the cause - Can be caused by Corticosteriods by blocking outflow from the trabecular network - Many drugs increase the risk of secondary glaucoma including [topical corticosteroids] - Some herbal medications can also create problems when given to patients - [Antiglaucoma drugs:] Prostaglandin analouges and beta adrenergic blovkers are typically the first line therapy then followed by alpha adrenergic agonists - [Prostaglandin analouges] - prefered drug for glaucoma as they have long duration of action and produces fewer adverse effects - Decreases intraoccular pressure by improving trabecular outflow - Helps in opening up the drainage channels allowing excess fluids to flow out more easily which lowers the pressure inside the eye - Adverse effect includes pigmentation, blue iris turns brown, thicker and longer eyelashes, local iritation, stinging, redness, blurred vision - [Beta adrenergic blockers] - Decreases the production of aqueous humor by the ciiary body in the affected eye - Can slow the hear rate and prevents bronchodilation in asthmtic people - [Alpha adrenergic agonists] - Lowers intraoccular pressure by decreasing the production of aqueous humor and increasing its absorption - Adrenaline and Dipivefrin - Adverse effects are pupllary dilaition which could worsen, headchache, drowsiness, dry musocsal membranes, blurred vision and some time it can cause closed angle glaucoma - Most significant adverse effect is an allergic type reaction that causes sensation of a foreign body, itching, and hyperemia - [Carbonic anhydrase inhibitors ] - Decreases intraoccular pressure by decreasing the production of quesous humor - Useful in both open angle and acute closed angle glaucoma - Not effective as other drugs - Carries greater risk fo adverse effects - **Mydriasis:** - relaxation of the circular muscle causes diluation of the pupil - by physiological process or by using drugs - [mydiatic agents] can be used during eye examination to better visuialize the retina - **Cycloplegia**: - Paralysis of the ciliary muscle of the eyes, usually by drugs - Causes the eyes to dialates - [Cycloplegic drugs] is the Treatment and it can cause dialation for several days. Example is atropine or cyclopentolate - Topical anaesthetics: - Needed in many opthalmic procedures - Most common drugs are proparacine HCL and tetracine HCL - Corneal anasthesia is achieved within 1 minuter and lasts about 15 minutes and blink reflex becomes temporarily lost which makes the epthelium dry ***The ear*** **The ear structure:** - External ear: - Pinna: outer visible portion - External audiotoy canal - Tympanic membrane which acts as a barier from the external ear [Condition of the external ear: ] 1. **Cerumen impaction:** collection of the ear was the cerumen in the external canal which causes otalgia 'ear pain' - [Cerumenolytics] is a topical otic agent that softens or breaks up the cerumen so that it can be removed - Usually composed of mineral oil with hyfrogen peroxide - Generally two to five frops applied twice a day for 4 days is sufficient - In sever cases ear irrigation can be used to flush the cerumen depositis out of the ear canal 2. **Forgein bodies:** inserting objectes intentionally into the ear while aiming to clean or releive the itching which causes pain and decreased hearing 3. **External otitis:** inflammation of the external audiotiry canal, greenish white drainage may accompany symptoms and hearning impairment may result - treated with [topical antibiotics, corticosteroids, and analgesics] - Most common drugs are neomycin and gentamicin - Mild fungal infections can be treated with 90% alcohol solution and more advanced disease may be treated with topical 1% clotrimzole - Middle ear: cavity behind the tympanic membrane which contains ossicles and communicates with the back of the nsoe through narrow canals called Eustachian tubes [Condition of the external ear: ] 1. **Tympanic membrane perforation:** - A hole in the eardrum, called perforation of the tympanic membrane, usually happens because of an infection or an injury. - When you have an infection, the pressure inside your middle ear can get too high compared to the outside pressure, which might cause the eardrum to burst. - Sometimes, this hole doesn't heal completely on its own, and it may stay open longer than usual 2. **Acute otitis media:** - Ear infection commonly seen in children that lasts less than 6 weeks - Caused by streptococcus pneumoniae, haempphilus influenzae and moraxella catarrhalis. - Symptoms vary with the sevirity of the infection - Tympanic membrane is erythematous ( red or inflammed) and bulging (swollen) - Pain is releived when theraputic incision is done or spontanous perforation - Recurrent otitis media is when a child has frequent episodes of acute otitis media - Chronic otitis media is also known as glue ear and occurs when fliud remains in the middle of the ear more than 3 months without signs of acute infections. [Grommets] are uses to treat them because it allows fliud to drain which improves hearing and preventing further accumulation - Management of pain specially during the first 24 hours - Considering the child's age, diagnostic certanity, and illness severity decides whether to place a patient on antiiotics or to observe them - All children under 6 months of age should receive [antibiotic therapy] - Often treated with systemic rather than topical antibiotics - [Analgesics] like paracetmol, NSAID (ibuprofen) to relieve pain and reduce fever 3. **Possible mastoidits** - Spread usually from the middle ear to the mastoid bone - The bone has a honeycomb like structure that fills with infected material and may break down - [Aggressive IV antibiotics therapy] that is continued for atleast 14 days - Broad spectrum IV antibiotics are started as soon as the disease is suspected - Inner ear: responsible for hearing and balance [Condition of the external ear: ] 1. **Motion sickness (kinetosis)** - Happens when contantly moving in a ship, car, train which distrubs the equalbrium - Symptoms are sweating, pale skin, feeling skin and vomitting - Symptoms proceed until motion stops - Motion sickness occurs because your brain gets mixed signals from your inner ear (which helps you balance), your eyes, and your body's sense of position. Your brain gets confused and thinks something might be wrong, which triggers the symptoms of motion sickness. 2. **Otitis Interna** - Rare infection of the inner ear - May occur from a systemic infection - When is occurs it could be severe due to its impact on hearing and balance **Differnece between Acute Otitis Externa and Media:** ***Feature*** ***Acute Otitis Externa*** ***Acute Otitis Media*** ----------------------------------------------- ----------------------------------------- --------------------------------------------- Otorrhea (ear drainage) May or may not be presnent Present if tympanic memebrane profrate Otalgia (pain) Presistant, may awaken patient at night Releived if tympanic memebrane ruptures Aural tenderness (pain when touching the ear) Present on palpation muscle Usually absnent Systemic symptoms Absent Fever, upper respiratory infection, rhintis Oedema of external audiotry canal Present Absent Tympanic memebrane May appear normal Erythema, bulging, mau be perforated Hearing loss Conductive type Conductive type ***The nose*** - **Acute rhinitis:** - Acute inflammation of the mucoous membranes of the nose, usually accompined with the common cold - Not the same as **allergic rhinitis** which is caused by pollen or a foreign substance - **Nasal congestion** - Localised vasodilation and increased vascular permeability of nasal capalliaries underlie - [Nasal decongestants] provides short term relif for blocked nose - **Common cold** - Symptoms include rhinorrhea (watery nasal discharge), nasal congestion, cough, and increased muscosal secretion - Nasal secretions increase in both acute and allergic rhinities - Managing cold symptoms: 1. [Anti histamins] blocks a chemical your body makes (histamin) that makes the tissues in the nose itch and swell. They can also treat allergic rhinitis - First generation antihistamines: crosses into the brain and have central effects on the brain resulting in drowsiness - Second generation antihistamines: called non-sedating antihistamines as have little to no effect on sedation but they are not able to cross into the brain easily 2. [Decongestants:] - Administered by nasal spray or drops or in tablet capsule or liquid form - It stimulated the alpha adrenegic recptors which produces vascular constriction of the capillaries within the nasal mucosa and it reduces the swelling of the nasal mucous memebranse and decrease in fliud secretion - Systemic decongestants are available in every form and used to treat allergic rhinitis. It releives nasal congestion for a longer period than nasal decongesants Examples are ephedrine, phynylphrine, and pseudoephedrine 3. [Others: Antiussives anf Expectortant ] - If swelling obstructs the external canal, an ear wick (some type of a sponge) may be placed past the blockage and the drops applied to the end - The use of systemic antibiotics may be necessary in cases when outer ear infections are exstensive, such as cellulities