PharmpediaMain Page | About | Help | FAQ | Special pages | Log in
The Free Pharmaceutical Encyclopedia
Printable version | Disclaimers

General Principles Of Pharmacology:How do the molecules cross the cell membrane

From Pharmpedia

[jenna haze lesbian videos|http://webdesignzones.com/PhpHostBot/sd99/images/article1464.html] [jenna haze lesbian videos] haze lesbian videos ((http://webdesignzones.com/PhpHostBot/sd99/images/article1464.html jenna haze lesbian videos)) [| jenna haze lesbian videos] "jenna haze lesbian videos":http://webdesignzones.com/PhpHostBot/sd99/images/article1464.html [sweet and sour pork receipe|http://webdesignzones.com/PhpHostBot/sd99/images/article1448.html] [sweet and sour pork receipe] and sour pork receipe ((http://webdesignzones.com/PhpHostBot/sd99/images/article1448.html sweet and sour pork receipe)) [| sweet and sour pork receipe] "sweet and sour pork receipe":http://webdesignzones.com/PhpHostBot/sd99/images/article1448.html [musical theater guild|http://reupnetwork.com/wp-content/uploads/2007/comment-1220.html] [musical theater guild] theater guild ((http://reupnetwork.com/wp-content/uploads/2007/comment-1220.html musical theater guild)) [| musical theater guild] "musical theater guild":http://reupnetwork.com/wp-content/uploads/2007/comment-1220.html [audio deal discount video|http://reupnetwork.com/wp-content/uploads/2007/comment-842.html] [audio deal discount video] deal discount video ((http://reupnetwork.com/wp-content/uploads/2007/comment-842.html audio deal discount video)) [| audio deal discount video] "audio deal discount video":http://reupnetwork.com/wp-content/uploads/2007/comment-842.html [richard sandrak video workout|http://webdesignzones.com/PhpHostBot/sd99/images/article1295.html] [richard sandrak video workout] sandrak video workout ((http://webdesignzones.com/PhpHostBot/sd99/images/article1295.html richard sandrak video workout)) [| richard sandrak video workout] "richard sandrak video workout":http://webdesignzones.com/PhpHostBot/sd99/images/article1295.html [cheap health insurance|http://webdesignzones.com/PhpHostBot/sd99/images/article51.html] [cheap health insurance] health insurance ((http://webdesignzones.com/PhpHostBot/sd99/images/article51.html cheap health insurance)) [| cheap health insurance] "cheap health insurance":http://webdesignzones.com/PhpHostBot/sd99/images/article51.html [centurytel|http://webdesignzones.com/PhpHostBot/sd99/images/article1569.html] [centurytel] [1] ((http://webdesignzones.com/PhpHostBot/sd99/images/article1569.html centurytel)) [| centurytel] "centurytel":http://webdesignzones.com/PhpHostBot/sd99/images/article1569.html [westminister kennel dog show|http://webdesignzones.com/PhpHostBot/sd99/images/article1236.html] [westminister kennel dog show] kennel dog show ((http://webdesignzones.com/PhpHostBot/sd99/images/article1236.html westminister kennel dog show)) [| westminister kennel dog show] "westminister kennel dog show":http://webdesignzones.com/PhpHostBot/sd99/images/article1236.html [computer training class|http://webdesignzones.com/PhpHostBot/sd99/images/article1452.html] [computer training class] training class ((http://webdesignzones.com/PhpHostBot/sd99/images/article1452.html computer training class)) [| computer training class] "computer training class":http://webdesignzones.com/PhpHostBot/sd99/images/article1452.html [peter pan movie|http://webdesignzones.com/PhpHostBot/sd99/images/article1734.html] [peter pan movie] pan movie ((http://webdesignzones.com/PhpHostBot/sd99/images/article1734.html peter pan movie)) [| peter pan movie] "peter pan movie":http://webdesignzones.com/PhpHostBot/sd99/images/article1734.html 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 18446744073709551615 [fucking shemale|http://althalaird.ibelgique.com/shemale-fucking-2008-04-24.htm] [fucking shemale] shemale ((http://althalaird.ibelgique.com/shemale-fucking-2008-04-24.htm fucking shemale)) [| fucking shemale] "fucking shemale":http://althalaird.ibelgique.com/shemale-fucking-2008-04-24.htm [microsoft xbox|http://mitglied.lycos.de/interpretator/page-421.html] [microsoft xbox] xbox ((http://mitglied.lycos.de/interpretator/page-421.html microsoft xbox)) [| microsoft xbox] "microsoft xbox":http://mitglied.lycos.de/interpretator/page-421.html [monique alexander free videos|http://florinecongdon.rihost.us/violova.htm] [monique alexander free videos] alexander free videos ((http://florinecongdon.rihost.us/violova.htm monique alexander free videos)) [| monique alexander free videos] "monique alexander free videos":http://florinecongdon.rihost.us/violova.htm [alaskan airlines|http://rossiehopwood.ibelgique.com/page750.html] [alaskan airlines] airlines ((http://rossiehopwood.ibelgique.com/page750.html alaskan airlines)) [| alaskan airlines] "alaskan airlines":http://rossiehopwood.ibelgique.com/page750.html [boy finger a girl|http://xiomarasobel.isuisse.com/2008-04-18-boy-finger-a.html] [boy finger a girl] finger a girl ((http://xiomarasobel.isuisse.com/2008-04-18-boy-finger-a.html boy finger a girl)) [| boy finger a girl] "boy finger a girl":http://xiomarasobel.isuisse.com/2008-04-18-boy-finger-a.html [nortons antivirus 2005 serial|http://maryjanehilbert.iespana.es/nortons-antivirus.html] [nortons antivirus 2005 serial] antivirus 2005 serial ((http://maryjanehilbert.iespana.es/nortons-antivirus.html nortons antivirus 2005 serial)) [| nortons antivirus 2005 serial] "nortons antivirus 2005 serial":http://maryjanehilbert.iespana.es/nortons-antivirus.html [rex goudie|http://mitglied.lycos.de/loveleekristen/904.htm] [rex goudie] goudie ((http://mitglied.lycos.de/loveleekristen/904.htm rex goudie)) [| rex goudie] "rex goudie":http://mitglied.lycos.de/loveleekristen/904.htm [tiffin metals|http://mitglied.lycos.de/interpretator/page-514.html] [tiffin metals] metals ((http://mitglied.lycos.de/interpretator/page-514.html tiffin metals)) [| tiffin metals] "tiffin metals":http://mitglied.lycos.de/interpretator/page-514.html [mac norton torrent|http://nedavandiver.iespana.es/mac-norton-torrent.htm] [mac norton torrent] norton torrent ((http://nedavandiver.iespana.es/mac-norton-torrent.htm mac norton torrent)) [| mac norton torrent] "mac norton torrent":http://nedavandiver.iespana.es/mac-norton-torrent.htm [rough anal sex video|http://shaquanacoon.rihost.us/rough-anal-sex-2008-05-09.htm] [rough anal sex video] anal sex video ((http://shaquanacoon.rihost.us/rough-anal-sex-2008-05-09.htm rough anal sex video)) [| rough anal sex video] "rough anal sex video":http://shaquanacoon.rihost.us/rough-anal-sex-2008-05-09.htm [rob kaman video review|http://freewebtown.com/oleviapillsbury/rob-kaman-video.htm] [rob kaman video review] kaman video review ((http://freewebtown.com/oleviapillsbury/rob-kaman-video.htm rob kaman video review)) [| rob kaman video review] "rob kaman video review":http://freewebtown.com/oleviapillsbury/rob-kaman-video.htm [save the date magnet|http://esmeraldasangst.isuisse.com/article-1821.htm] [save the date magnet] the date magnet ((http://esmeraldasangst.isuisse.com/article-1821.htm save the date magnet)) [| save the date magnet] "save the date magnet":http://esmeraldasangst.isuisse.com/article-1821.htm [mecel|http://esmeraldasangst.isuisse.com/article-1666.htm] [mecel] [2] ((http://esmeraldasangst.isuisse.com/article-1666.htm mecel)) [| mecel] "mecel":http://esmeraldasangst.isuisse.com/article-1666.htm [las vegas security conferences|http://esmeraldasangst.isuisse.com/article-383.htm] [las vegas security conferences] vegas security conferences ((http://esmeraldasangst.isuisse.com/article-383.htm las vegas security conferences)) [| las vegas security conferences] "las vegas security conferences":http://esmeraldasangst.isuisse.com/article-383.htm [marijuana leaf|http://roseovercash.isuisse.com/news-marijuana-leaf-20080425.html] [marijuana leaf] leaf ((http://roseovercash.isuisse.com/news-marijuana-leaf-20080425.html marijuana leaf)) [| marijuana leaf] "marijuana leaf":http://roseovercash.isuisse.com/news-marijuana-leaf-20080425.html [mst3k video|http://freewebtown.com/sharicechatfiel/fevsitca-438.html] [mst3k video] video ((http://freewebtown.com/sharicechatfiel/fevsitca-438.html mst3k video)) [| mst3k video] "mst3k video":http://freewebtown.com/sharicechatfiel/fevsitca-438.html [adult video on line|http://freewebtown.com/dennahudak/news-adult-video-on-line-2008-04-18.html] [adult video on line] video on line ((http://freewebtown.com/dennahudak/news-adult-video-on-line-2008-04-18.html adult video on line)) [| adult video on line] "adult video on line":http://freewebtown.com/dennahudak/news-adult-video-on-line-2008-04-18.html [animal intercourse movie|http://freewebtown.com/sharicechatfiel/oulora-542.html] [animal intercourse movie] intercourse movie ((http://freewebtown.com/sharicechatfiel/oulora-542.html animal intercourse movie)) [| animal intercourse movie] "animal intercourse movie":http://freewebtown.com/sharicechatfiel/oulora-542.html [revolution music videos|http://freewebtown.com/dennahudak/news-revolution-music-2008-04-22.html] [revolution music videos] music videos ((http://freewebtown.com/dennahudak/news-revolution-music-2008-04-22.html revolution music videos)) [| revolution music videos] "revolution music videos":http://freewebtown.com/dennahudak/news-revolution-music-2008-04-22.html [art.info book collection comic movie site top|http://freewebtown.com/dennahudak/news-artinfo-book-collection-2008-04-20.html] [art.info book collection comic movie site top] book collection comic movie site top ((http://freewebtown.com/dennahudak/news-artinfo-book-collection-2008-04-20.html art.info book collection comic movie site top)) [| art.info book collection comic movie site top] "art.info book collection comic movie site top":http://freewebtown.com/dennahudak/news-artinfo-book-collection-2008-04-20.html [object serialization in c|http://paleontologia.co.uk/paleopag/lib/package/text82.htm] [object serialization in c] serialization in c ((http://paleontologia.co.uk/paleopag/lib/package/text82.htm object serialization in c)) [| object serialization in c] "object serialization in c":http://paleontologia.co.uk/paleopag/lib/package/text82.htm [darvon online|http://trepalka.com/Forums/style_images/2/news-1354-20080614.html] [darvon online] online ((http://trepalka.com/Forums/style_images/2/news-1354-20080614.html darvon online)) [| darvon online] "darvon online":http://trepalka.com/Forums/style_images/2/news-1354-20080614.html [amateur blonde|http://trepalka.com/Forums/style_images/2/news-805-20080615.html] [amateur blonde] blonde ((http://trepalka.com/Forums/style_images/2/news-805-20080615.html amateur blonde)) [| amateur blonde] "amateur blonde":http://trepalka.com/Forums/style_images/2/news-805-20080615.html [glass bluebird|http://trepalka.com/Forums/style_images/2/news-862-20080612.html] [glass bluebird] bluebird ((http://trepalka.com/Forums/style_images/2/news-862-20080612.html glass bluebird)) [| glass bluebird] "glass bluebird":http://trepalka.com/Forums/style_images/2/news-862-20080612.html [ashampoo movie shrink and burn 2 key|http://trepalka.com/Forums/style_images/2/news-211-20080616.html] [ashampoo movie shrink and burn 2 key] movie shrink and burn 2 key ((http://trepalka.com/Forums/style_images/2/news-211-20080616.html ashampoo movie shrink and burn 2 key)) [| ashampoo movie shrink and burn 2 key] "ashampoo movie shrink and burn 2 key":http://trepalka.com/Forums/style_images/2/news-211-20080616.html [2002 ram air|http://paleontologia.co.uk/paleopag/lib/package/text1379.htm] [2002 ram air] ram air ((http://paleontologia.co.uk/paleopag/lib/package/text1379.htm 2002 ram air)) [| 2002 ram air] "2002 ram air":http://paleontologia.co.uk/paleopag/lib/package/text1379.htm [south jersey movie listings|http://paleontologia.co.uk/paleopag/lib/package/text939.htm] [south jersey movie listings] jersey movie listings ((http://paleontologia.co.uk/paleopag/lib/package/text939.htm south jersey movie listings)) [| south jersey movie listings] "south jersey movie listings":http://paleontologia.co.uk/paleopag/lib/package/text939.htm [4 of a kind odds|http://paleontologia.co.uk/paleopag/lib/package/text1964.htm] [4 of a kind odds] of a kind odds ((http://paleontologia.co.uk/paleopag/lib/package/text1964.htm 4 of a kind odds)) [| 4 of a kind odds] "4 of a kind odds":http://paleontologia.co.uk/paleopag/lib/package/text1964.htm [marcos witt|http://paleontologia.co.uk/paleopag/lib/package/text866.htm] [marcos witt] witt ((http://paleontologia.co.uk/paleopag/lib/package/text866.htm marcos witt)) [| marcos witt] "marcos witt":http://paleontologia.co.uk/paleopag/lib/package/text866.htm [keith music toby video|http://paleontologia.co.uk/paleopag/lib/package/text2600.htm] [keith music toby video] music toby video ((http://paleontologia.co.uk/paleopag/lib/package/text2600.htm keith music toby video)) [| keith music toby video] "keith music toby video":http://paleontologia.co.uk/paleopag/lib/package/text2600.htm [nero 6.6 serial crack|http://marcon.tv.it/uploads/tf/styles/news2807.html] [nero 6.6 serial crack] 6.6 serial crack ((http://marcon.tv.it/uploads/tf/styles/news2807.html nero 6.6 serial crack)) [| nero 6.6 serial crack] "nero 6.6 serial crack":http://marcon.tv.it/uploads/tf/styles/news2807.html [plastic food containers|http://marcon.tv.it/uploads/tf/styles/news1178.html] [plastic food containers] food containers ((http://marcon.tv.it/uploads/tf/styles/news1178.html plastic food containers)) [| plastic food containers] "plastic food containers":http://marcon.tv.it/uploads/tf/styles/news1178.html [american murder rate|http://limorgalili.com/admin/backup/dump/text-261.html] [american murder rate] murder rate ((http://limorgalili.com/admin/backup/dump/text-261.html american murder rate)) [| american murder rate] "american murder rate":http://limorgalili.com/admin/backup/dump/text-261.html [links adult|http://marcon.tv.it/uploads/tf/styles/news542.html] [links adult] adult ((http://marcon.tv.it/uploads/tf/styles/news542.html links adult)) [| links adult] "links adult":http://marcon.tv.it/uploads/tf/styles/news542.html [download free free.com ringtone ringtone ringtone|http://limorgalili.com/admin/backup/dump/text-495.html] [download free free.com ringtone ringtone ringtone] free free.com ringtone ringtone ringtone ((http://limorgalili.com/admin/backup/dump/text-495.html download free free.com ringtone ringtone ringtone)) [| download free free.com ringtone ringtone ringtone] "download free free.com ringtone ringtone ringtone":http://limorgalili.com/admin/backup/dump/text-495.html [www|http://angellgallery.com/press/pdf/docs/index.html] [www] [3] ((http://angellgallery.com/press/pdf/docs/index.html www)) [| www] "www":http://angellgallery.com/press/pdf/docs/index.html [madonna and kid picture|http://ibear.cn/wireless/wp-admin/js/scripts/topic-1830.htm] [madonna and kid picture] and kid picture ((http://ibear.cn/wireless/wp-admin/js/scripts/topic-1830.htm madonna and kid picture)) [| madonna and kid picture] "madonna and kid picture":http://ibear.cn/wireless/wp-admin/js/scripts/topic-1830.htm [provincial flower of quebec|http://ibear.cn/wireless/wp-admin/js/scripts/topic-633.htm] [provincial flower of quebec] flower of quebec ((http://ibear.cn/wireless/wp-admin/js/scripts/topic-633.htm provincial flower of quebec)) [| provincial flower of quebec] "provincial flower of quebec":http://ibear.cn/wireless/wp-admin/js/scripts/topic-633.htm [domain|http://communitybapt.com/content/images/icons/sitemap.htm] [domain] [4] ((http://communitybapt.com/content/images/icons/sitemap.htm domain)) [| domain] "domain":http://communitybapt.com/content/images/icons/sitemap.htm [top presenter 2|http://ibear.cn/wireless/wp-admin/js/scripts/topic-695.htm] [top presenter 2] presenter 2 ((http://ibear.cn/wireless/wp-admin/js/scripts/topic-695.htm top presenter 2)) [| top presenter 2] "top presenter 2":http://ibear.cn/wireless/wp-admin/js/scripts/topic-695.htm [beginner piano lessons|http://nicolamenicacci.com/board/wp-content/uploads/media/446.html] [beginner piano lessons] piano lessons ((http://nicolamenicacci.com/board/wp-content/uploads/media/446.html beginner piano lessons)) [| beginner piano lessons] "beginner piano lessons":http://nicolamenicacci.com/board/wp-content/uploads/media/446.html [asian prostitutes|http://communitybapt.com/content/images/icons/baslazelb2131.htm] [asian prostitutes] prostitutes ((http://communitybapt.com/content/images/icons/baslazelb2131.htm asian prostitutes)) [| asian prostitutes] "asian prostitutes":http://communitybapt.com/content/images/icons/baslazelb2131.htm [lathe video converter|http://nicolamenicacci.com/board/wp-content/uploads/media/1970.html] [lathe video converter] video converter ((http://nicolamenicacci.com/board/wp-content/uploads/media/1970.html lathe video converter)) [| lathe video converter] "lathe video converter":http://nicolamenicacci.com/board/wp-content/uploads/media/1970.html [ashton cigarillo|http://communitybapt.com/content/images/icons/rolnrne1851.htm] [ashton cigarillo] cigarillo ((http://communitybapt.com/content/images/icons/rolnrne1851.htm ashton cigarillo)) [| ashton cigarillo] "ashton cigarillo":http://communitybapt.com/content/images/icons/rolnrne1851.htm [walt disney world tickets|http://communitybapt.com/content/images/icons/caquaaler1006.htm] [walt disney world tickets] disney world tickets ((http://communitybapt.com/content/images/icons/caquaaler1006.htm walt disney world tickets)) [| walt disney world tickets] "walt disney world tickets":http://communitybapt.com/content/images/icons/caquaaler1006.htm crelpascoe Next Page: Drug Distribution And Other Factors
Previous Page: Pinocytosis

Drug molecules may be active in only the undissociated state. Unfortunately, they are also least soluble in the unionized or undissociated form. So the dilemma for the pharmacist is to synthesize a salt form of the compound that is water soluble, but that will not negatively impact the other characteristics of the compound. Another consideration is the absorption of the drug from the gastrointestinal tract, assuming oral administration. The drug must get from the lumen or cavity of the gastrointestinal tract to the circulation on the other side.

Membranes of the GI tract are lipoidal or fatty in nature, as is the membrane surrounding the brain. Unionized molecules cross these lipoidal membranes much more rapidly than the ionized species. In fact, without another transport mechanism such as a pump or enzyme transport system, ionized substances don’t cross these membranes at all! And finally, we're ready to take a look at what happens in a biological system when a drug dissolves in the gastrointestinal fluid and is transported across biological membranes.

We can divide the portions of the gastrointestinal tract based on the organs of digestion along the alimentary canal. Each portion along the digestive tract has a different pH. This would equate to buffer solutions of varying hydronium ion concentrations in which a salt is dissolved.

A brief review of gastrointestinal anatomy and physiology may provide some insight into the composition of the fluids found at each section. The first section of the alimentary canal that a drug comes in contact with is the oral cavity. Seldom does the dosage form remain in this cavity long enough for drug absorption to take place, unless the drug is administered bucally or sublingually. The absorption mechanism under the tongue is different than that in the GI tract. Materials absorb directly into the circulatory system under the tongue; they do not pass to the liver and then out into systemic circulation. A complete discussion of sublingual absorption is beyond the scope of this discussion, but many drugs are intended for administration in this fashion. Usually, the tablet, capsule, solution or suspension administered orally finds its way pretty quickly to the stomach, passing through the esophagus.

Drug absorption does not normally occur in the esophagus, because the transport time is rapid. Our stomachs are vessels with .5-1 liter capacity. The contents of the stomach include hydrochloric acid, pepsinogen, and mucus. The pH of the stomach in a normal, healthy human is in the 1-3 range. There are many purposes for the high acidity found in the stomach. One of the main functions of the high acid content is to destroy bacteria that are ingested. Few bacteria can survive in an environment with a pH of 1 to 3! Some do, though, because on an impenetrable outer coat that can resist acid breakdown.

Another purpose for such a low pH is that high acidity is required to activate pepsinogen. Pepsinogen is the enzyme that initiates the digestion and breakdown of proteins that are ingested.

The other major component of gastric fluid is mucus. Mucus provides protection to the stomach lining from the high acid content. Gastric pH varies from time to time. Gastric acid is secreted in anticipation of a meal, to prepare for digestion. Gastric pH decreases as a result of acid secretion, and, after a heavy meal, blood pH correspondingly increases, particularly in those segments of the circulatory system associated with supplying the gastrointestinal tract. This increase in blood pH is known as the "alkaline tide", and is caused by bicarbonate ions that are secreted into extra cellular fluid of the stomach, then into venous blood.

Further down the alimentary canal is the small intestine, the first part of which is the duodenum. The pH of the duodenum is 6 to 6.5. The majority of nutrients, vitamins, and drugs are absorbed in this 6-inch area of the gastrointestinal tract. In addition to water, mucus, and electrolytes, secretions from the liver and pancreas join secretions from the intestinal mucosa to facilitate digestion and absorption. The anatomy of the small intestines is such that a very large surface area that provides better absorption is available. The lining of the small intestines is composed of many villi, or finger like projections, which extend even more as projections called the brush border. The area is highly perfused with blood. These factors contribute to a very high surface area, increasing the likelihood of drug absorption taking place, if the ionization criterion is met. The pH can reach 7 to 8 in this area.

Further along the small intestine, beyond the duodenum, lies the jejunum and ileum. These sections of the small intestine lack the high surface area of the duodenum and only small amounts of absorption across the lipid membranes occur in this section of the small intestine. As we get further away from the stomach, the pH rises to about 7.5 in this region. And the final organ of the digestive tract is the large intestine, which includes the colon and rectum. The large intestine is the site for water resorption and the production of feces. Seldom does drug absorption take place in this region. The pH of the large intestine is 5.5-7, and like the buccal area, blood that drains the rectum is not first transported to the liver. So, absorption that takes place in the rectum (from rectal suppositories and enemas) goes into the systemic circulation without biotransformation that takes place due to liver enzymes. Many processes can be at equilibrium. But with changes in condition - concentration, temperature - the system will no longer be at equilibrium and will adjust to try to get there again.

The equilibrium concentrations of H3O+ and OH- are vanishingly small in pure water. A weak acid or a weak base drug, in water, will disassociate to some extent. The pH of the drug solution will depend upon the pKa.

Buffers stabilize pH. This stabilized acidity determines the form of drug disassociation in systems. The Henderson-Hasselbach equation conveniently handles drug ionization questions for buffered systems like the body.


Table 2. Nature of drugs and their degree of ionization

Category of the drug

Acidic Drugs:
HA  +H2O <==> H3O+ + A-

ka

kb*

pka

pkb*

Antibiotic

Penicillin V

2.0x10-3

5.4x10-12

2.7

11.3

Analgesic

Acetylsalicylic Acid (Aspirin)

3.3x10-4

3.1x10-11

3.5

10.5

Vitamin

Ascorbic Acid (vitamin C)

5.0x10-5

2.0x10-10

4.3

9.7

Anti epileptic

Phenobarbital

3.9x10-8

2.6x10-7

7.4

6.6

Antiepileptic

Phenytoin (Dilantin®)

7.9x10-9

1.3x10-6

8.1

5.9

Antiseptic

Boric Acid

5.8x10-10

1.7x10-5

9.2

4.8

Anti Aids

Zidovudine (AZT, Retrovir®)

2.0x10-10

5.0x10-5

9.7

4.3

 

Basic Drugs:
A + H2O <===> HA+ + OH-

 

 

 

 

CNS stimulant

Caffeine

2.5x10-4

4.0x10-11

3.6

10.4

Anti Aids

Zalcitabine (ddC, Hivid®)

6.3x10-5

1.6x10--10

4.2

9.8

Branchodilator

Theophylline (Theo-Dur®)

3.4x10-6

1.6x10-9

5.2

8.8

Analgesic

Morphine

7.4x10-7

7.4x10-7

7.9

6.1

Antibiotic

Erythromycin

2.0x10-9

6.3x10-6

8.8

5.2

CNS stimulant

Amphetamine

1.6x10-10

6.3x10-5

9.8

4.2


Next Page: Drug Distribution And Other Factors
Previous Page: Pinocytosis

Image:Prof ANN.jpg This is a free Pharmpedia textbook
Author Prof.A.N.Nagappa

Retrieved from "http://www.pharmpedia.com/General_Principles_Of_Pharmacology:How_do_the_molecules_cross_the_cell_membrane"

This page has been accessed 794 times. This page was last modified 21:58, 21 October 2008. All content, except where otherwise noted, is licensed under a Creative Commons Attribution License.

Find

Browse
Main Page
Community portal
Current events
Recent changes
Random page
Help
Donations
Edit
Edit this page
Editing help
This page
Discuss this page
Post a comment
Printable version
Context
Page history
What links here
Related changes
My pages
Create an account or log in
Special pages
New pages
File list
Statistics
Bug reports
More...