G200 Units 1-3

What is ionization and how it pertains to the movement of a drug?

  • Discuss factors which influence the rate of drug passage through membranes including the size and shape of the molecule, its lipid solubility, and its degree of ionization especially as influenced by the pH of the surrounding medium.

    • Size & shape of drug molec.- SMALL

    • Lipid-solubility of drug- LIPID-LOVERS

      • Cell membrane interior > hydrophobic

    • Degree of drug ionization- NONIONIZED / NON CHARGED

      • The greater the degree, the less likely absorbed

      • Cell membranes repel charged particles

      • Ionized > "trapped"!!

    • pH of local environment- make pH of drug the same

      • Stomach acid- aspirin nonionized, more likely absorbed

      • Small intestine- aspirin ionized, less likely absorbed

What are the differences between potency and efficacy?

  • Compare and contrast the terms potency and efficacy.

    • Efficacy- effectiveness of drug producing pharmacologic response; how well does it relieve symptoms

      • NOT HOW MUCH person has to take for effect

      • Magnitude of max. response can produced from particular drug

    • Potency- amount of drug actually taken to produce pharmacologic response; quantitative; depends on DOSE

      • HOW MUCH person has to take for effect

      • NOT related to max. effect

    • Higher potency drug > therapeutic effect at lower dose

    • Lower potency drug > therapeutic effect at higher dose

What are the drug schedules/prescription writing procedures?

  • Identify the five drugs schedules and be familiar with the prescription writing procedure for drugs on the schedule.

    • **According to potential for abuse & medical usefulness

    • Schedule 1 (most strict)

      • Use forbidden except for research

      • All drugs start here even if destined to become

        • OTC

        • Regular "legend" prescription medications

        • "controlled substances"

      • Remain here if no therapeutic use even w/ medical supervision (bc too high potential for abuse)

      • Only available for RESEARCH; researchers MUST apply to FDA for clearance to use

    • Schedule 2

      • High potential for abuse

        • Sever psychological / physiological dependence

        • ie. Morphine, methadone, secobarbital (short acting, lipid soluble, barbiturate), amphetamines

      • Prescription may not be refilled

        • Cannot be faxed in,

        • Max. 30 day supply

        • Must rewrite prescription on "security paper"

      • Emergency in managed care setting- may be renewed by telephone BUT written prescription must follow in 72 hrs

    • Schedule 3

      • Abuse potential medium

        • Moderate to low physical dependence

        • Perhaps high psychological dependence                                                                                                                                                    

          • ie. Many of barbiturates (especially longer acting), drugs combined with codeine / other narcotics (higher concentration than in cough syrup)

          • Must renew prescriptions for schedule 3-5 medications after 6 months or 5 refills.

          • May be renewed by telephone / FAX (but need a security form with required license numbers & info.)

    • Schedule 4

      • Lower potential for abuse

        • May lead to limited physical / psychological dependence

          • ie. Include some tranquilizers

        • Same prescription issues as schedule 3 but different penalties for illegal possession

    • Schedule 3 & 4

      • Does not differ in how prescribed (can be different in penalties for illegal possession)

      • Prescription can be refilled up to five times OR good for only 6 months, may be given to pharmacist by telephone (if pharmacist writes down immediately)

    • Schedule 5

      • No prescription necessary (but still federally controlled)

        • Small amount of controlled narcotic (NOT in CA including "signature drugs")

      • Pharmacy keeps record of purchaser, address, date, etc. for 2 yrs

How are drugs named (trade names, generic names, etc.)?

  • Distinguish among a drug's chemical name, generic (official) name, and trade name.

    • Chemical name- describes drug's exact chemical composition; useful if you are chemist

    • Generic name can be official name if drug included in USP

      • Official name- used in official drug reference, USP; used to be two with NF - combined

      • Generic name

        • Older drugs- handed down thru antiquity

        • Newer drugs- "code" name given during testing phase, based on chemical name; decided by USAN committee

    • Trade name- aka proprietary, product, brand name; copyrighted name whose use is restricted to single company; exclusive rights for 17 yrs. post-NDA submission; renewable, any other drug company can

  • Explain the differences between trade-name drugs and their generic equivalents.

    • Trade-name drugs- the "default" drugs branded by the company itself; marketing, selling, branding, etc.

    • Generic equivalents- drugs with "filler" ingredients that may cause problems; the inactive stuff does NOT have to be the same, but the active stuff has to be the same; most recognizable, doesn’t matter who makes it esp. after drug off-patent

      • trade name & generic medications work the same is important!!!

What are the advantages of the major drug reference books?

  • Recognize various American drug references as being official or nonofficial and identify the type of information contained in each.

    • Pharmacopeia of the USA (USP)

      • Published in 1820, renewed every 5 yrs w/ supplements as need

        • Single drugs

        • Full time directors, voluntary team of pharmacologists, physicians, etc.

        • Older drugs deleted in favor of newer, effective agents

          • Authoritative- gives avg dose, toxicity, methods of administration

          • Also- how to prep drugs, standards for tablet disintegration, etc.

    • National Formulary (NF)

      • Published independently 1888-1975, now combined with USP

      • Single drugs & formulas for drug mixes

      • Often included drugs deleted from USP

    • AMA Drug evals

      • Prepped by appointed experts

      • Drugs grouped according to use

      • General discussion provided of each group

      • Favorable and unfavorable judgements expressed

    • Physician's desk reference (PDR)

      • One for non-prescription medications too

      • Manufacturers buy space

      • Info similar to drug inserts

      • Cross-referenced to generic & chemical names

      • Esp. useful section on drug ID & dosage forms

        • No "unlabeled" or "off-label" uses listed

      • Maybe getting smaller bc drug manufacturers are going more online

    • Drug facts & Comparisons

      • Drugs grouped according to use

      • Comparison of various drug forms

      • Now includes color photo section (including OTC)

      • American hospital formulary service (AHFS)

      • Similar to DF&C

      • Pharmacists use

    • Other sources

      • Journals- nursing & medical journals, the medical letter

      • Package insert- must be approved by FDA, legally may only include "labeled" uses, others may include "unlabeled" uses

      • Textbooks- the pharmacological basis of therapeutics by Gilman, Goodman, Gilman 

What are the differences between local vs. systemic drug administration?

  • Differentiate between local and systemic drug activity.

    • Local drug activity- intended to act where it is placed; on skin, mucus membranes; some gray areas (sprays, etc.)

    • Systemic actions- drug action absorbed then distributed throughout body; action may be on whole body or specific target organ

    • Toxic effects may occur when drug intended for local effects become systemically absorbed