Pharmacology Notes

Major drugs uses, Action and Adrs

OPHTHALMIC DRUGS
Drug	Action	Treatment uses	Adverse reactions
Antiallergic agents
Azelastine	Decrease irritation	To treat allergic conjunctivitis	Tearing
Cromolyn		To treat seasonal conjunctivitis
Emedastine		To treat keratitis
Ketotifen
Lodoxamide
Olopatadine
Anesthetics
Proparacaine	Prevent the initiation and transmission of nerve impulses	To anesthetize the cornea, allowing application of instruments for measuring intraocular pressure (I0P) or removing foreign bodies	Corneal inflammation
Tetracaine			Corneal opacities
			Delayed corneal healing
			Eye pain and redness
		To prepare for suture removal, conjunctival or corneal scraping, and tear duct manipulation	Loss of visual acuity
			Scarring
Anti-infectives
Ciprofloxacin	Kill bacteria or inhibit growth of bacteria or viruses	To treat corneal ulcers or conjunctivitis caused by bacteria, fungus, or virus (each drug is specific to particular organisms)	Secondary eye infections (with prolonged use)
Erythromycin
Gentamicin			Severe hypersensitivity reactions
Levofloxacin
Natamycin
Norfloxacin
Ofloxacin
Sulfacetamide
Sulfisoxazole
Tobramycin
Trifluridine
Anti-inflammatories
Steroidalanti-anti-inflammatories	Decrease leukocyte infilinfiltration at inflammation sites, causing reduced oozing of fluids and reduced edema, redness, and scarring	To treat inflammatory disorders and hypersensitivity-related conditions of the cornea, iris, conjunctiva, sclera, and anterior uvea	Corneal ulcération
			Delayed corneal healing
Dexamethasone			Increased susceptibility to viral or fungal corneal infection
Fluorometholone
Loteprednol
Prednisolone
Rimexolone
Nonsteroidal anti-inflammatories	Decrease inflammation and itching	To inhibit pupil constriction during surgery (flurbiprofen and suprofen)	Tearing, discomfort
Diclofenac		To reduce itching due to seasonal allergies (ketorolac)
Flurbiprofen
Ketorolac		To treat inflammation after surgery
Suprofen
Lubricants
Methylcellulose	Act as artificial tears	To protect cornea during diagnostic procedures	None
Polyvinyl alcohol	Moisten cornea
		To moisten contact lenses
Miotics
Carbachol	Stimulate and contract the sphincter muscle of the iris, constricting the pupil	To treat open-angle glaucoma, acute and chronic angle-closure glaucoma, and certain cases of secondary glaucoma resulting from increased IOP	Blurred vision
Pilocarpine	Improve aqueous outflow		Bronchospasm
			Cataractformation
			Eye pain
			Photosensitivity
			Reversible iris cysts
Mydriatics
Dipivefrin	Acton the iris to dilate the pupil	To dilate the pupils for intraocular examinations	Blurred vision
Epinephrine			Confusion
Hydroxyamphetamine	Lower I0P	To lower I0P in patients with glaucoma	Dry skin
Phenylephrine				Flushing
			Impaired ability to coordinate movement
			Irritation
			Rapid heart rate
			Transient burning sensations
Mydriatics and cycloplegics
Atropine sulfate	Act on the ciliary body of the eye to paralyze the fine-focusing muscles (thereby preventing accommodation for near vision)	To perform refractive eye examinations in children before and after ophthalmic surgery	Same as for mydriatics
Cyclopentolate hydrochloride
Homatropine hydrobromide		To treat conditions involving the iris
Tropicamide
Other drugs to lower IOP
Adrenergic blockers (topical)	May reduce aqueous humor formation and slightly increase aqueous humor outflow	To prevent and control elevated IOP, chronic open-angle glaucoma, and secondary glaucoma	Bronchospasm
			Fatigue
Apraclonidine			Headaches
Betaxolol	outflow		Slow heart rate
Brimonidine
Carteolol
Levobunolol
Metipranolol
Timolol maleate
Carbonic anhydrase inhibitors	Inhibit action of carbonic anhydrase, thus decreasing aqueous humor production	To treat chronic open angle glaucoma, acute angle-closure episodes, and secondary glaucoma	Hemolytic or aplastic anemia
			Hypokalemia
Acetazolamide			Leukopenia
Brinzolamide			Nausea and vomiting
Dorzolamide
Osmotic agents Glycerin	Reduce volume of vitreous humor	To prepare for intraocular surgery	«Hypokalemia
		To treat acute glaucoma	«Diuresis
Isosorbide	Decrease IOP
Mannitol
Prostaglandin analogues	Decrease IOP	To treat glaucoma	«Irritation
			Tearing
Bimatoprost
Latanoprost
Travoprost
Unoprostone

OTIC DRUGS
Drug	Action	Treatment uses	Adverse reactions
Anesthetics (local)
Benzocaine	Temporarily interrupt the conduction of nerve im-pulses	To temporarily relieve ear pain	Ear irritation or itching Edema Hives Masking of the symptoms of a fulminating middle ear infection
Anti-infectives
Acetic acid	Kill bacteria or inhibit bacterial growth Inhibit fungal growth (acetic acid and boric acid)	To treat otitis externa To treat otitis media (colistin and polymyxin B sulfate)	Burning Dermatitis Ear itching Hives
Boric acid
Chloramphenicol
Colistin sulfate
Neomycin sulfate
Polymyxin B sulfate
Anti-inflammatories
Hydrocortisone	Inhibit edema, capillary dilation, fibrin deposition, and phagocyte and leuko-cyte migration Reduce capillary and fi-broblast proliferation, col-lagen deposition, and scar formation	To treat inflammatory conditions of the external ear canal	Masking or exacerbation of underlying otic infection Transient local stinging or burning sensations
Dexamethasone-sodium phosphate
Cerumenolytics
Carbamide peroxide Triethanolamine polypeptide	Reduce hardened ceru-men by emulsifying and mechanically loosening it	To loosen and remove cerumen from the ear canal	Mild, localized redness and itching

DERMATOLOGIC DRUGS
Drug	Action	Treatment uses	Adverse reactions
Anti-infectives
Antibacterials Azelaic acid Bacitracin Clindamycin Erythromycin Gentamicin Mafenide Metronidazole Mupirocin Neomycin Silver sulfadiazine Sulfacetamide sodium Tetracycline	Kill or inhibit the growth of bacteria	To treat infections caused by bacteria (each drug is specific to particular organisms; combination products may also be used)	Contact dermatitis Rash Skin burning, itching, and red-ness Skin dryness Stinging
Antifungals Amphotericin B Butenafine Ciclopirox Clotrimazole Econazole Ketoconazole Miconazole Naftifine Nystatin Oxiconazole Sulconazole Terbinafine	Kill or inhibit the growth of fungiof bacteria	To treat infections caused by fungi (each drug is specific to particular or-ganisms)	Same as for antibacterials
Antivirals Acyclovir Penciclovir	Inhibit the growth of herpes virus	To treat herpes genitalis or herpes labialis	Same as for antibacterials
Anti-inflammatories	Alclometasone Betamethasone dipropionate Clobetasol Clocortolone Desonide Desoximetasone Dexamethasone Diflorasone diacetate Fluocinolone Fluocinonide Flurandrenolide Fluticasone Halcinonide Halobetasol Hydrocortisone Mometasone Triamcinolone acetonide	Suppress inflammation by binding to intracellular corticosteroid receptors, initiating a cascade of anti-inflammatory mediators Cause vasoconstriction in inflamed tissue and pre-vent macrophages and leukocytes from moving into the area	To relieve inflammation and itching in topical steroid-responsive disorders, such as eczema, psoriasis, angioedema, contact dermatitis, sebor-rheic dermatitis, atopic dermatitis, and hives
Hair growth stimulants
Minoxidil	Stimulate hair growth by causing vasodilation, which increases blood flow to the skin (exact mecha-nism of action is unknown)	To treat male and female pattern baldness	Fluid retention Rapid heart rate Weight gain
Topical antiacne drugs
Keratolytics Acitretin Adapalene Isotretinoin Tazarotene Tretinoin Counterirritants Benzoyl peroxide	Produce antibacterial effects Reduce inflammation Produce antibacterial effects Reduce inflammation	To treat mild acne, oily skin, and acne vulgaris (oral antibiotic therapy used as needed for deep acne) To treat mild acne, oily skin, and acne vulgaris (oral antibiotic therapy used as needed for deep acne)	Burning Hives Rash Scaling, blistering, and peeling Skin dryness Skin irritation Superinfection (with prolonged use) Same as for keratolytics
Antimicrobials Clindamycin Doxycycline Erythromycin Minocycline Tetracycline	Produce antibacterial effects Reduce inflammation	To treat mild acne, oily skin, and acne vulgaris (oral antibiotic therapy used as needed for deep acne)	Same as for keratolytics Hypersensitivity reactions (oral) Candidal vaginitis (oral) Gram-negative pustular folliculitis (oral)
Scabicides and pediculicides
Gamma benzene hexachloride Lindane Malathion Permethrin	Act on parasite nerve cell membranes to disrupt the sodium channel current, causing paralysis (some are also ovicidal)	To treat scabies and lice	Contact dermatitis Hypersensitivity reactions Respiratory allergy symptoms

Dissolution
In the most common situation, a tablet is ingested and passes through the esophagus to the stomach. Because the stomach is an aqueous environment, this is the first place where a tablet may dissolve.

The rate of dissolution is a key target for controlling the duration of a drug's effect, and as such, several dosage forms that contain the same active ingredient may be available, differing only in the rate of dissolution. If a drug is supplied in a form that is not readily dissolved, the drug may be released more gradually over time with a longer duration of action. Having a longer duration of action may improve compliance since the medication will not have to be taken as often. Additionally, slow-release dosage forms may maintain concentrations within an acceptable therapeutic range over a long period of time, as opposed to quick-release dosage forms which may result in sharper peaks and troughs in serum concentrations.

The rate of dissolution is described by the Noyes-Whitney equation as shown below:

Where:
is the rate



Where:

* \frac{dW}{dt} is the rate of dissolution.
* A is the surface area of the solid.
* C is the concentration of the solid in the bulk dissolution medium.
* Cs is the concentration of the solid in the diffusion layer surrounding the solid.
* D is the diffusion coefficient.
* L is the diffusion layer thickness.

As can be inferred by the Noyes-Whitney equation, the rate of dissolution may be modified primarily by altering the surface area of the solid. The surface area may be adjusted by altering the particle size (e.g. micronization). The rate of dissolution may also be altered by choosing a suitable polymorph of a compound. Specifically, crystalline forms dissolve slower than amorphous forms.

Also, coatings on a tablet or a pellet may act as a barrier to reduce the rate of dissolution. Coating may also be used to modify where dissolution takes place. For example, enteric coatings may be applied to a drug, so that the coating only dissolves in the basic environment of the intestines. This will prevent release of the drug before reaching the intestines.

Since solutions are already dissolved, they do not need to undergo dissolution before being absorbed.

Dissolution
In the most common situation, a tablet is ingested and passes through the esophagus to the stomach. Because the stomach is an aqueous environment, this is the first place where a tablet may dissolve.

The rate of dissolution is a key target for controlling the duration of a drug's effect, and as such, several dosage forms that contain the same active ingredient may be available, differing only in the rate of dissolution. If a drug is supplied in a form that is not readily dissolved, the drug may be released more gradually over time with a longer duration of action. Having a longer duration of action may improve compliance since the medication will not have to be taken as often. Additionally, slow-release dosage forms may maintain concentrations within an acceptable therapeutic range over a long period of time, as opposed to quick-release dosage forms which may result in sharper peaks and troughs in serum concentrations.

The rate of dissolution is described by the Noyes-Whitney equation as shown below:

Where:
is the rate



Where:

* \frac{dW}{dt} is the rate of dissolution.
* A is the surface area of the solid.
* C is the concentration of the solid in the bulk dissolution medium.
* Cs is the concentration of the solid in the diffusion layer surrounding the solid.
* D is the diffusion coefficient.
* L is the diffusion layer thickness.

As can be inferred by the Noyes-Whitney equation, the rate of dissolution may be modified primarily by altering the surface area of the solid. The surface area may be adjusted by altering the particle size (e.g. micronization). The rate of dissolution may also be altered by choosing a suitable polymorph of a compound. Specifically, crystalline forms dissolve slower than amorphous forms.

Also, coatings on a tablet or a pellet may act as a barrier to reduce the rate of dissolution. Coating may also be used to modify where dissolution takes place. For example, enteric coatings may be applied to a drug, so that the coating only dissolves in the basic environment of the intestines. This will prevent release of the drug before reaching the intestines.

Since solutions are already dissolved, they do not need to undergo dissolution before being absorbed.

 Drug Absorption
In pharmacology (and more specifically pharmacokinetics), absorption is the movement of a drug into the bloodstream.

Absorption involves several phases. First, the drug needs to be introduced via some route of administration (oral, via the skin, etc.) and in a specific dosage form such as a tablet, capsule, and so on.

In other situations, such as intravenous therapy, intramuscular injection, enteral nutrition and others, absorption is even more straight-forward and there is less variability in absorption and bioavailability is often near 100%.

Absorption is a primary focus in drug development and medicinal chemistry, since the drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption.

 Drug Absorption
In pharmacology (and more specifically pharmacokinetics), absorption is the movement of a drug into the bloodstream.

Absorption involves several phases. First, the drug needs to be introduced via some route of administration (oral, via the skin, etc.) and in a specific dosage form such as a tablet, capsule, and so on.

In other situations, such as intravenous therapy, intramuscular injection, enteral nutrition and others, absorption is even more straight-forward and there is less variability in absorption and bioavailability is often near 100%.

Absorption is a primary focus in drug development and medicinal chemistry, since the drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption.

 Drug Absorption
In pharmacology (and more specifically pharmacokinetics), absorption is the movement of a drug into the bloodstream.

Absorption involves several phases. First, the drug needs to be introduced via some route of administration (oral, via the skin, etc.) and in a specific dosage form such as a tablet, capsule, and so on.

In other situations, such as intravenous therapy, intramuscular injection, enteral nutrition and others, absorption is even more straight-forward and there is less variability in absorption and bioavailability is often near 100%.

Absorption is a primary focus in drug development and medicinal chemistry, since the drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption.