option d medicinal chem

theraputic window

the range of dosages between the minimum amounts of the drug that produced the desired effect and a medically unacceptable adverse effect

dosage

The amount of a drug taken at one time, and the frequency of taking it

therapeutic index

a ratio that compares the effective dose of a drug to the toxic dose (in humans) or lethal dose (in animals

effective dose

dose that is effective in 50% of the population

lethal dose

dose that is lethal to 50% of the population

toxic dose

dose that is toxic to 50% of the population

theraputic index in animals

LD50/ED50

theraputic index in humans

TD50/ED50

high theraptuc index means

large theraputic window so safer to consume ex:penicillin

low theraputic index means

small theraputic window so less safe to consume ex: warfarin

tolerance

when a person is given repeated dose of a drug a higher dose is required to acieve a theraputic effect,as the drug becomes less effective

addiction / dependence

a condition where there is an inability to function without being able to take a substance

bioavailability

The fraction of the administered dosage that reaches the target part of the human body.

which method of administration has 100% bioavailability

intraveneous injection

true or false: polar drugs have greater bioaviablability as they are more soluble in the aqueous solutions of blood

true

non-polar molecules effectivness

Drugs that are more non-polar can cross the lipid cell membranes efficiently and enter the blood, ex; the blood brain barrier

analgesic

a substance which reduces pain

explain how mild analgesics function

by intercepting the pain stimulus at the source, often by interfering with the production of substances that cause pain, swelling or fever.

function of asprin

it is a mild analgesic which reduces swelling , inflammation and fever

where was asprin orginally found

in willow bark, actually the compound salicylic acid was converted to asprin (its ester derivative) as salicylic acidirritated the stomach .

explain the process of asprin synthesis

• salicylic acid is reacted with ethanoic anhydride

• and warmed gently in the presence of conc. sulphuric or phosphoric acid

explain importance of beta lactum structure in antibiotics likep encillin

• The atoms in the beta-lactam ring are at 90° and this puts them under strain. This means that the bonds in the beta-lactam ring break easily.

• When penicillin breaks its beta-lactam ring, it is able to bind to a bacterial enzyme and so block the action of the enzyme.

explian how pencillin works

• Penicillin inhibits the enzyme transpeptidase responsible for forming cross linkages in the cell wall, thereby it prevents the formation of cross-links in the cell walls of the bacteria. This causes the bacteria
  to burst and die.

how is pencillin made more resistant

the r-groups of the pencillin antibiotic are modified , due to the resistance of some pencillium bacteria, which produce the enzyme pencilillase responsible for breaking the beta lactam ring structure.

• These forms of the antibiotic are more resistant to the penicillinase enzyme. As a result, these drugs are more effective against resistant bacteria.

opiates definition

natural narcotic analgesics that are derived from the opium poppy. they are strong analgesics

explain how strong analgesics work

Strong analgesiscs temporarily binding to receptor sites

in the brain, preventing the transmission of pain impulse without depressing the central nervous system.

potency of strong analgesics from least to highest

codeine , morphine , diamorphine(heroin)

Skill: description and explanation of use of strong analgesics

• Opiates act as drugs by binding to opioid receptors in the brain. This is the

  reason for both their therapeutic effects and their side-effects.

• The therapeutic effect of strong analgesics is relief from severe pain.

• The side-effects of opiates include constipation, constriction of the pupil of the eye and effects on brain function, called narcotic effects.

• Narcotic effects include a lowering of brain activity, sleepiness and addiction.

opiates provide the best relief from strong pain in the short term, however it can lead to dependece on the drug leading to addiction