DDS LEC FINALS
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DDS LEC FINALS - Details
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| 🇬🇧 | 🇬🇧 |
| Facilitate the passage of therapeutic quantities of drug substances through the skin and into the general circulation for their systemic effect | Transdermal drug delivery systems (TDDSs) |
| 1 first conceived of the percutaneous absorption of drug substances. 2 First transdermal system approved by FDA | 1) 1965: Stoughton 2) 1979: Scopolamine (TRANSDERM SCOP) |
| 1 For transdermal drug delivery, it is considered ideal if the drug penetrates through the skin to the underlying blood supply without __ | 1 without drug buildup in the dermal layers. |
| Routes of Skin Permeation | 1 Transcellular route (within the lipid bilayer) 2 Intercellular route (between the lipid bilayer - polar) |
| Benefits of TDDS | 1 Eliminates potential pain associated with injections 2 No first pass metabolism in liver 3 Eliminates gastrointestinal side effect 4 Improves patient compliance due to simpler, pain free delivery 5 Potential for home administration |
| Factors affecting percutaneous absorption | 1) Drug concentration 2) The larger the area of application(larger TDDS), the more drug is absorbed 3 Aqueous solubility of a drug and Partition coefficient - Drugs penetrate the skin better in their un-ionized form - Nonpolar drugs penetrate lipid rich regions - Polar drugs favor transport between cells 4 Drugs with molecular weights of 100 to 800 and adequate lipid and aqueous solubility can permeate skin. The ideal molecular weight of a drug for transdermal drug delivery is believed to be 400 or less 5 Hydration of the skin generally favors percutaneous absorption. 6 Percutaneous absorption greater when thin horny layer 7 longer the medicated application contact - greater total absorption |
| 1 increase percutaneous absorption of therapeutic agents. 2 increases skin permeability by reversibly damaging or altering the physicochemical nature of the stratum corneum to reduce its diffusional resistance | 1 Percutaneous absorption enhancers 2 Chemical enhancers |
| What are the alterations of Chemical Enhancers? | 1 INCREASED HYDRATION of the stratum corneum 2 A CHANGE IN TEH STRUCTURE of the lipids and lipoproteins in the intercellular channels |
| LIST OF skin penetration enhancers | Acetone, azone, dimethyl acetamide, dimethyl formamide, dimethyl sulfoxide (DMSO) ethanol, oleic acid, polyethylene glycol, propylene glycol, sodium lauryl sulfate |
| The selection of a permeation enhancer should be based on: | 1 its efficacy in enhancing skin permeation 2 its dermal toxicity (low) 3 its physicochemical and biologic compatibility with the system’s other components. |
| Is a delivery of a charged chemical compound across the skin membrane using an electrical field. | Iontophoresis |
| A number of drugs have been the subject of iontophoretic studies, they include | Lidocaine dexamethasone amino acids, peptides insulin Verapamil Propranolol |
| It is thought that high-frequency ultrasound can influence the integrity of the stratum corneum and thus affect its penetrability. Among the agents examined are: | 1 hydrocortisone, 2 lidocaine, 3 salicylic acid in such formulations as gels, creams, and lotions |
| Transdermal drug delivery systems may be constructed of a number of layers, including: | 1) an occlusive backing membrane to protect the system from environmental entry and from loss of drug from the system or moisture from the skin 2) Drug reservoir or matrix system; store and release the drug at the skin-site; 3) a release liner, which is removed before application and enables drug release; 4) an adhesive layer to maintain contact with the skin after application. |
| TDDSs may be categorized into two types: | 1 Monolithic 2 Membrane-controlled systems |
| 1 incorporate a drug matrix layer between backing and frontal layers. 2 designed to contain a drug reservoir, or pouch, usually in liquid or gel form, a rate-controlling membrane, and backing, adhesive, and protecting layers. | 1 Monolithic systems 2 Membrane-controlled transdermal systems |
| 1 composed of a polymeric material in which the drug is dispersed. 2 controls the rate at which the drug is released for percutaneous absorption. | 1 drug-matrix layer 2 polymer matrix |
| With or without excess of drug In the preparation of monolithic systems, the1 __ and the 2 __ are 3 __ | 1 drug 2 polymer 3 dissolved or blended together, cast as the matrix, and dried BCD |
| Commonly used Adhesive Layer | Polybutyl acrylate |
| Two types of Adhesive layers | 1 Peripheral Adhesive 2 Face Adhesive |
| Design objectives of TDDS | 1. Deliver the drug to the skin for percutaneous absorption at therapeutic levels at an optimal rate 2. Contain medicincal agents having the necessary physicochemical characteristics to release from the system and partition into the stratum corneum 3. Occlude the skin to ensure one way flux of the drug into the stratum corneum 4. Have a therapeutic advantage over other dosage forms and DDS 5. Not irritate or sensitize the skin 6. Adhere well to the patient's skin and have size, appearance, and site placement that encourage acceptance. |
| Protect the system from environmental entry and from loss of drug from the system or moisture from the skin; | Occlusive backing membrane |
| Store and release the drug at the skin-site; | Drug reservoir or matrix system |
| Removed before application and enables drug release; | Release liner |
| Maintain contact with the skin after application. | Adhesive layer |
| In vivo skin penetration studies may be undertaken for one or more of the following purposes: | 1 To verify and quantify the cutaneous BIOAVAILABILITY of a topically applied drug. 2 To verify and quantify the systemic BIOAVAILABILITY of a transdermal drug. 3) To establish BIOEQUIVALENCE of different topical formulations of the same drug substance. 4) To determine the incidence and degree of systemic TOXICOLOGIC RISK following topical application of a specific drug or drug product. 5) To relate resultant blood levels of drug in human to systemic therapeutic effects. |
| IN VIVO STUDIES 1 The most relevant studies are performed in humans, however, animal models may be used insofar as they may be effective as predictors of human response. Animal models include: __ 2 Biologic samples used in drug penetration and drug absorption studies include | 1 weanling pig, rhesus monkey, and hairless mouse or rat 2 skin sections, venous blood from the application site, blood from the systemic circulation, and excreta (urine, feces, and expired air). |
| IN VITRO STUDIES 1 Skin permeation may be tested in vitro using various __ in a diffusion cell. 2 In vitro penetration studies using human skin are limited because of difficulties of __ 3 Animal skins are much more permeable than human skin. One alternative that has been shown to be effective is __ | 1 skin tissues (human or animal whole skin, dermis or epidermis) 2 procurement, storage, expense, and variation in permeation. 3 shed snake skin (Elaphe obsoleta, black rat snake) |
| IN VITRO STUDIES 1 Test for cell culture studies or in standard diffusion cells | 1 Living Skin Equivalent Test skin |
| 1 are employed in vitro to quantify the release rates of drugs from topical preparations 2 In these systems, __ may be employed as barriers to the flow of drug and vehicle to simulate the biologic system | 1 Diffusion cell systems 2 skin membranes or synthetic membranes |
| Advantages of TDDSs | 1 AVOID GASTROINTESTINAL DRUG ABSORPTION DIFFICULTIES caused by gastrointestinal pH, enzymatic activity and drug interactions with food, drink, or other orally administered drugs. 2 SUBSTITUTE FOR ORAL ADMINISTRATION of medication when that route is unsuitable, as in instances of vomiting and/or diarrhea. 3. AVOID FIRST-PASS EFFECT 4. NONINVASIVE, AVOIDING THE INCONVENIENCE OF PARENTERAL THERAPY 5. EXTENDED THERAPY WITH SINGLE APPLICATION, thereby improving patient compliance over other dosage forms requiring more frequent dose administration. 6. The activity of drugs having short half-lives is extended through the reservoir of drug present in the therapeutic delivery system and its controlled release characteristics. 7 Drug therapy may be terminated rapidly by removal of the application from the surface of the skin. 8 Ease of rapid identification of the medication in emergencies (e.g., nonresponsive, unconscious, or comatose patient) due to the physical presence of TDDS |
| Disadvantages of TDDSs | 1. Only relatively POTENT DRUGS are suitable candidates for transdermal delivery due to the natural limits of drug entry imposed by the skin’s impermeability. 2. Some patients may develop CONTACT DERMATITIS at the site of application due to one or more of the system components, necessitating discontinuation. |
| Examples of transdermal drug delivery systems | 1 Transdermal scopolamine 2 Transdermal Nitroglycerin 3 Transdermal clonidine 4 Transdermal Nicotine 5 Transdermal Estradiol SNCNE (SENSYA NA) |
| The first TDDS to receive FDA approval. is a circular flat patch 0.2 mm thick and 2.5 cm2 in area. | Transdermal scopolamine (Transderm-Scop) |
| The TDDS (Transderm-Scop) contains __ and is designed to deliver approximately __ at an approximately constant rate to the systemic circulation over the __ life-time of the system. | 1) 1.5 mg of scopolamine 2) 1 mg of scopolamine 3) 3 day |
| Transdermal scopolamine (Transderm-Scop) is worn in __ | Hairless area behind the ear. Because of the small size of the patch, the system is unobtrusive, convenient, and well accepted by the patient. |
| A number of nitroglycerin-containing TDDSs have been developed: __ | 1 Deponit (Schwarz) 2 Minitran (3M Pharmaceuticals) 3 Nitro-Dur (Key) 4 Transderm-Nitro (Novartis) Each of these products maintains nitroglycerin drug delivery for 24 HOURS after application. |
| CONSTRUCTION OF NITROGLYCERIN SYSTEM 1 four-layer drug pouch system 2 thin two-layer matrix system resembling 3 Nitroglycerin TDDS should be placed in the __ 4 may increase the absorption of nitroglycerin. | . 1 Transderm-Nitro TDDS 2 Deponit TDDS 3 chest, back, upper arms, or shoulders. 4 physical exercise and elevated ambient temperatures (such as in a sauna) |
| The first transdermal system for hypertension, was marketed in 1985. | Catapres TTS (clonidine transdermal therapeutic system, Boehringer Ingelheim) |
| 1 Catapres TTS amount of drug released is proportional to the __ 2 To ensure constant release over the 7-day use period, the drug content is __ (CATAPRES TTS) | 1 patch size 2 greater than the total amount of drug delivered. |
| 1 Clonidine flows in the direction of the lower concentration at a constant rate limited by a rate-controlling membrane. TRUE OR FALSE | 1 TRUE The system is applied to the hairless area of intact skin on the upper outer arm or chest. |
| 1 used as adjuncts in smoking cessation programs. | 1 Nicotine TDDSs (Transdermal Nicotine) |
| 1 users of nicotine TDDSs are more than twice as likely to quit smoking than individuals wearing a __ 2 provide sustained blood levels of nicotine as “nicotine-replacement-therapy” to help the patient establish and sustain remission from __ 3 The commercially available patches contain __ of nicotine 4 nicotine TDDS usually is applied to __ | 1 placebo patch. 2 smoking 3) 7 to 22 mg 4 arm or upper front torso, with patients advised not to smoke when wearing the system. |
| 1 Testosterone transdermal systems examples 2 Transdermal testosterone application | 1 Testoderm (Alza), Androderm (SmithKline Beecham) 2 applied daily, usually in the morning to mimic endogenous testosterone release. |
| Other transdermal therapeutic systems | Diltiazem Isosorbide dinitrate Propranolol Nifedipine Mepindolol Verapamil |
| Other transdermal therapeutic systems 1 for hormonal contraception 2 for Alzheimer’s disease therapy 3 for substance addiction 4 for anxiety 5 for smoking cessation 6 male impotence | 1 levonorgestrel/estradiol 2 Physostigmine 3 Naltrexone and methadone 4 Buspirone 5 Bupropion 6 Papaverine |
| 1 may vary with the site of application. (Rotating locations) 2 TDDSs should be applied to clean, dry skin that is | 1 Percutaneous absorption 2 free of hair and not oily, irritated, inflamed, broken, or callused. |
| TDDSs should be applied to clean, dry skin that is | Free of hair and not oily, irritated, inflamed, broken, or callused. |
| TDDSs should not be physically altered by __, since this destroys the integrity of the system. | Cutting |
| 1 Civilization to use suppositories 2 There is a continuous tendency not to use rectal delivery for routine administration. TRUE OR FALSE | 1 Ancient Egypt 2 TRUE |
| 1 for treatment in male erectile dysfunction 2 for post menopausal women | 1 Urethral suppository 2 Progesterone vaginal inserts |
| Suppositories have been generally employed for three reasons | 1. Promote defecation 2. Introduce drugs into the body 3. Treat anorectal diseases (like hemorrhoids) |
| Often not first choice good alternative for oral route low cost and lack of technical difficulties compared to parenteral therapy | Rectal administration |
| DOWNSIDE OF Rectal administration | Stigma of violating patient's dignity AND aesthetics, potential rectal irritation, difficulty in titrating correct dose |
| Rectal administration advantages | Essential in palliative medicine Excellent dosage forms for patients who does not want to administer numerous injections daily Administered to avoid nausea and vomiting for Paediatric and hospice patients Fast onset of action |
| Suppositories latin and meaning | Latin: "supponere" meaning 'to place under' sub (under) ponere (to place) |
| Solid dosage forms that is inserted into a naturally occurring (nonsurgical) body cavity other than mouth or rectum, including vagina and urethra. Tablet in appearance | Insert ex. Monistat |
| Convenient form for administering topical drugs. | Medication sticks ex. Mentholatum (medicated lip stick) Oxy (acne medication) |
| Suppository, Insert and Stick shapes various shapes: __ | 1 Round oval 2 Long oval 3 Teardrop 4 Bullet 5 Tampon |
| 1 Rectal Suppositories Length and Shape 2 Adult rectal suppositories Weight 3 What shape is mostly available in the market? | 1) 32 mm (1.5 inches) in length Cylindrical, one or both ends tapered. Some are Bullet shaped, Torpedo or The Little Finger 2) about 2 grams when cocoa butter (theobroma oil) is used as a base. 3) Bullet Shaped |
| Vaginal Inserts shape | 1 Globular 2 Oviform 3 Teardrop 4 Bullet 5 Tampon |
| Called bougies, are slender, pencil-shaped suppositories intended for insertion into the male or female urethra. | Urethral suppositories |
| 1 Male urethral suppositories Length and Weight 2 Female urethral suppositories Length and Weight | 1) 140 mm long, 4 g (Cocoa Butter is employed as base) 2) 70 mm long (half), 2 g (half) |
| Advantages of Rectal Administration | 1. Avoidance of first-pass effect 2. Drug stability- avoiding breakdown of drugs that are susceptible to gastric degradation 3. Large dose drugs: Ability to administer somewhat large dose of drugs than oral administration 4. Irritating drugs: ability to administer drugs that have an irritating effect on the oral or GI mucosa 5. Unpleasant tasting and smelling drugs 6. Rectal route is especially useful for children 7. Patient experiencing nausea and vomiting, unconscious 8. Presence of dx of the upper GI tract that interferes drug absorptions 9. Objectional taste or odor of a drug ( impt. in children) 10. Achievement of rapid drug effect systemically (alternate to injection) |
| Disadvantages of Rectal Administration | 1. A perceived lack of flexibility regarding dosage of commercially available suppositories in underuse and a lack of availability 2. If made on demand, may be EXPENSIVE 3. Exhibit VARIABLE EFFECTIVENESS 4. Formulations with NARROW THERAPEUTIC MARGIN, cannot be interchanged w/o risk of toxicity 5. Bullet shaped suppository after insertion can leave the anorectal site and ascend to rectostigmoid and descending colon, should not be used at bedtime 6. Defecation may interrupt the absorption process of drug, occur if drug is irritating 7. The absorbing SA of the rectum is much smaller than that of the small intestine 8. Fluid content of the rectum is much less than that of the SI, which may affect dissolution rate 9. Possibility of degradation of some drugs by the microflora present in the rectum 10. Dose of drug may be greater or less than the dose of the oral drug 11. Factors that affect rectal absorption of a drug administered in the form of suppository: a. anatomic and physiologic factors b. physicochemical factors of the drug and the base |
| Used to relieve constipation, as laxative | RECTAL SUPPOSITORIES FOR LOCAL EFFECT/ ACTION Ex. Dulcolax (Bisacodyl) suppositories Glycerin suppositories |
| Promote laxation by local irritation of the mucous membranes, due to the dehydrating effect of the glycerin on those membranes | Glycerin suppositories |
| Used to relieve pain, irritation, itching, and inflammation associated with hemorrhoids and other anorectal conditions example suppositories | RECTAL SUPPOSITORIES FOR LOCAL EFFECT/ ACTION ex. Hydrocortisone suppositories Mesalamine suppositories |
| Frequently contain a number of components, including : Local anesthetics, vasoconstrictors, astringents, analgesics, soothing emollients, and protective agents. | Antihemorrhoidal suppositories |
| 1 __ permit the absorption of many soluble drugs. 2 site for the systemic absorption of drugs 3 not as frequently used | 1 Mucous membranes of the rectum and vagina 2 Rectum 3 Vagina |
| 1 Physiologic factors affecting the absorption of drugs from rectal suppositories 2 Physicochemical factors | 1 Colonic content (Emptier, the more absorption), Circulation route (Avoids first pass effect), pH and lack of buffering capacity of the rectal fluids 2 Lipid-water solubility, Particle Size, Nature of the base Mnemonic: CCP, LPN |
| 1 For systemic effect, absorption is greater in a rectum that is __ 2 They slow down rectal drug absorption | 1 void or empty 2 Diarrhea, Fecal matter, Tumor growth, Tissue dehydration Mnemonics: DFTT |