Compositions and methods for enhancing drug delivery across and into epithelial tissues

• US 6,593,292 B1
• Filed: 08/24/2000
• Issued: 07/15/2003
• Est. Priority Date: 08/24/1999
• Status: Expired due to Fees

• Current Assignee: Kai Pharmaceuticals, Inc. (Amgen Inc.)
• Original Assignee: Cellgate, Inc. (Tbg Diagnostics Limited)
• Inventors: Wender, Paul A., McGrane, P. Leo, Rothbard, Jonathan B., Kirschberg, Thorsten A., Sista, Lalitha V. S.
• Primary Examiner(s): Russel, Jeffrey E.
• Application Number:
  US09/648,400
• Time in Patent Office: 1,055 Days
• Field of Search: 424/1.69, 424/9.322, 424/9.323, 424/9.34, 424/9.341, 424/9.1, 424/9.411, 424/433, 424/434, 424/435, 424/436, 424/449, 424/427, 424/428, 424/437, 514/2, 514/3, 514/11, 514/12, 514/13, 514/14, 514/15, 514/16, 514/17, 514/634, 514/636, 514/169, 514/456, 514/291, 514/252.13, 514/252.14, 514/252.19, 514/383, 514/423, 514/263, 514/166, 514/457, 514/458, 514/269, 514/198, 514/199, 514/200, 514/152, 514/25, 514/262, 514/635, 514/159, 514/254.07, 530/300, 530/302, 530/303, 530/315, 530/317, 530/321, 530/324, 530/325, 530/326, 530/327, 530/328, 530/329, 530/330, 564/225, 564/230, 564/236, 564/243, 564/233, 544/366
• US Class Current: 514/1.2
• CPC Class Codes: A61K 47/54 the modifying agent being an organic compound
• CPC Class Codes: A61K 47/55 the modifying agent being also a pharmacologically or therapeutically active agent, i.e. the entire conjugate being a codrug, i.e. a dimer, oligomer or polymer of pharmacologically or therapeutically active compounds
• CPC Class Codes: A61K 47/557 the modifying agent being biotin
• CPC Class Codes: A61K 47/62 the modifying agent being a protein, peptide or polyamino acid
• CPC Class Codes: A61K 47/645 Polycationic or polyanionic oligopeptides, polypeptides or polyamino acids, e.g. polylysine, polyarginine, polyglutamic acid or peptide TAT
• CPC Class Codes: A61K 47/665 the pre-targeting system, clearing therapy or rescue therapy involving biotin-(strept) avidin systems
• CPC Class Codes: A61K 49/0043 Fluorescein, used in vivo
• CPC Class Codes: A61K 49/0056 Peptides, proteins, polyamino acids
• CPC Class Codes: A61K 49/085 conjugated systems
• CPC Class Codes: A61K 49/146 the peptide being a polyamino acid, e.g. poly-lysine
• CPC Class Codes: A61P 1/04 for ulcers, gastritis or reflux esophagitis, e.g. antacids, inhibitors of acid secretion, mucosal protectants
• CPC Class Codes: A61P 11/00 Drugs for disorders of the respiratory system
• CPC Class Codes: A61P 11/06 Antiasthmatics
• CPC Class Codes: A61P 11/08 Bronchodilators
• CPC Class Codes: A61P 17/00 Drugs for dermatological disorders
• CPC Class Codes: A61P 17/02 for treating wounds, ulcers, burns, scars, keloids, or the like
• CPC Class Codes: A61P 25/00 Drugs for disorders of the nervous system
• CPC Class Codes: A61P 25/06 Antimigraine agents
• CPC Class Codes: A61P 25/08 Antiepileptics; Anticonvulsants
• CPC Class Codes: A61P 25/16 Anti-Parkinson drugs
• CPC Class Codes: A61P 25/18 : Antipsychotics, i.e. neuroleptics; Drugs for mania or schizophrenia
• CPC Class Codes: A61P 25/24 : Antidepressants
• CPC Class Codes: A61P 25/28 : for treating neurodegenerative disorders of the central nervous system, e.g. nootropic agents, cognition enhancers, drugs for treating Alzheimer's disease or other forms of dementia
• CPC Class Codes: A61P 29/00 : Non-central analgesic, antipyretic or antiinflammatory agents, e.g. antirheumatic agents; Non-steroidal antiinflammatory drugs [NSAID]
• CPC Class Codes: A61P 3/02 : Nutrients, e.g. vitamins, minerals
• CPC Class Codes: A61P 31/04 : Antibacterial agents
• CPC Class Codes: A61P 31/12 : Antivirals
• CPC Class Codes: A61P 35/00 : Antineoplastic agents
• CPC Class Codes: A61P 37/06 : Immunosuppressants, e.g. drugs for graft rejection
• CPC Class Codes: A61P 37/08 : Antiallergic agents antiasthmatic agents A61P11/06; ophthalmic antiallergics A61P27/14
• CPC Class Codes: A61P 43/00 : Drugs for specific purposes, not provided for in groups A61P1/00-A61P41/00
• CPC Class Codes: A61P 5/00 : Drugs for disorders of the endocrine system
• CPC Class Codes: B82Y 5/00 : Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery
• CPC Class Codes: C07K 7/06 : having 5 to 11 amino acids
• CPC Class Codes: C07K 7/64 : Cyclic peptides containing only normal peptide links

Abstract

This invention provides compositions and methods for enhancing delivery of drugs and other agents across epithelial tissues, including the skin, gastrointestinal tract, pulmonary epithelium, and the like. The compositions and methods are also useful for delivery across endothelial tissues, including the blood brain barrier. The compositions and methods employ a delivery enhancing transporter that has sufficient guanidino or amidino sidechain moieties to enhance delivery of a compound conjugated to the reagent across one or more layers of the tissue, compared to the non-conjugated compound. The delivery-enhancing polymers include, for example, poly-arginine molecules that are preferably between about 6 and 25 residues in length.

Claims

1. A method for enhancing delivery of a compound into and across one or more layers of an animal epithelial or endothelial tissue, the method comprising:

contacting the endothelial or epithelial tissue with a conjugate that comprises the compound attached to a delivery-enhancing transporter by a linker,

wherein the delivery-enhancing transporter comprises sufficient guanidino or amidino moieties to increase delivery of the conjugate into and across one or more intact epithelial or endothelial tissue layers compared to delivery of the compound in the absence of the delivery-enhancing transporter; and

the conjugate has a structure selected from the group consisting of structures 3, 4, 5 and 6, as follows;

 

wherein;

R₁—

X comprises the compound;

X is a functional group on the compound to which the linker is attached;

Y is N or CH;

R₂ is hydrogen, alkyl, aryl, acyl, or allyl;

R₃ comprises the delivery-enhancing transporter;

R₄ is unsubstituted O, substituted N or C or substituted or unsubstituted S;

R₅ is OH, SH or NHR₆;

R₆ is hydrogen, alkyl, aryl, acyl or allyl;

k and m are each independently selected from 1 and 2;

n is 1 to 10; and

Ar is an aryl group having the attached radicals arranged in an ortho or para configuration, which aryl group can be substituted or unsubstituted.

2. The method of claim 1, wherein X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

3. The method of claim 1, wherein the conjugate comprises structure 3 and R₂ is selected to obtain a conjugate half-life of between 5 minutes and 24 hours.

4. The method of claim 1, wherein the conjugate comprises structure 3, Y is N, and R₂ is methyl, ethyl, propyl, butyl, allyl, benzyl or phenyl.

5. The method of claim 1, wherein R₂ is benzyl;

k, m, and n are each 1, and X is O.

6. The method of claim 1, wherein the conjugate comprises structure 4;

R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

7. The method of claim 1, wherein the conjugate comprises structure 4;

R₅ is NHR₆;

R₆ is hydrogen, methyl, allyl, butyl or phenyl; and

k and m are each 1.

8. The method of claim 1, wherein the conjugate comprises structure 6 and X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

9. The method of claim 1, wherein the conjugate comprises structure 6 and R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

10. The method of claim 1, wherein the delivery-enhancing transporter comprises a non-peptide backbone.

11. The method of claim 1, wherein the delivery-enhancing transporter comprises from 5 to 25 guanidino or amidino moieties.

12. The method of claim 11, wherein the delivery-enhancing transporter comprises between 7 and 15 guanidino moieties.

13. The method of claim 1, wherein the delivery-enhancing transporter comprises at least 6 contiguous guanidino and/or amidino moieties.

14. The method of claim 1, wherein the delivery-enhancing transporter consists essentially of 5 to 50 amino acids, at least 50 percent of which amino acids are arginines or analogs thereof.

15. The method of claim 14, wherein the delivery-enhancing transporter comprises 5 to 25 arginine residues or analogs thereof.

16. The method of claim 15, wherein at least one arginine is a D-arginine.

17. The method of claim 16, wherein all of the arginines are D-arginines.

18. The method of claim 14, wherein at least 70 percent of the amino acids that comprise the delivery-enhancing transporter are arginines or arginine analogs.

19. The method of claim 14, wherein the delivery-enhancing transporter comprises at least 5 contiguous arginines or arginine analogs.

20. The method of claim 1, wherein delivery of the compound into and across the intact epithelial tissue layers is at least two-fold greater than that of the compound conjugated to a basic HIV tat peptide consisting of residues 49-57.

21. The method of claim 1, wherein the compound is selected from the group consisting of immunosuppressives, antibacterials, antifungals, antivirals, antiproliferatives, hormones, antuinflammatories, vitamins, and analgesics.

22. The method of claim 20, wherein the compound is an immunosuppressive.

23. The method of claim 22, wherein the immunosuppressive is cyclosporin.

24. The method of claim 20, wherein the compound is an analgesic.

25. The method of claim 1, wherein the epithelial tissue is the skin.

26. The method of claim 1, wherein the epithelial tissue is an eye.

27. The method of claim 1, wherein the epithelial tissue is a gastrointestinal epithelium.

28. The method of claim 1, wherein the epithelial tissue is a bronchial epithelium.

29. The method of claim 1, wherein the compound is cyclosporin.

30. The method of claim 1, wherein the compound is a glucocorticoid or ascomycin.

31. A method for enhancing delivery of a compound into and across one or more layers of an animal epithelial and endothelial tissue, the method comprising:

contacting the epithelial tissue with a conjugate that comprises the compound and a delivery-enhancing transporter,

wherein the delivery-enhancing transporter comprises sufficient guanidino or amidino moieties to increase delivery of the conjugate into and across one or more intact epithelial or endothelial tissue layers compared to delivery of the compound in the absence of the delivery-enhancing transporter; and

wherein the epithelial tissue comprises a blood vessel and the compound enters the blood vessel from the epithelial tissue.

32. The method of claim 31, wherein the compound exerts its biological effect after entry into the capillary system.

33. The method of claim 31, wherein the delivery-enhancing transporter comprises a non-peptide backbone.

34. The method of claim 31, wherein the delivery-enhancing transporter is not attached to an amino acid sequence to which the delivery enhancing transporter molecule is attached in a naturally occurring protein.

35. The method of claim 31, wherein the delivery-enhancing transporter comprises from 5 to 25 guanidino or amidino moieties.

36. The method of claim 31, wherein the delivery-enhancing transporter comprises between 7 and 15 guanidino moieties.

37. The method of claim 31, wherein the delivery-enhancing transporter comprises at least 6 contiguous guanidino and/or amidino moieties.

38. The method of claim 31, wherein the delivery-enhancing transporter consists essentially of 5 to 50 amino acids, at least 50 percent of which amino acids are arginines or analogs thereof.

39. The method of claim 38, wherein the delivery-enhancing transporter comprises 5 to 25 arginine residues or analogs thereof.

40. The method of claim 39, wherein at least one arginine is a D-arginine.

41. The method of claim 40, wherein all of the arginines are D-arginines.

42. The method of claim 38, wherein at least 70 percent of the amino acids that comprise the delivery-enhancing transporter are arginines or arginine analogs.

43. The method of claim 38, wherein the delivery-enhancing transporter comprises at least 5 contiguous arginines or arginine analogs.

44. The method of claim 31, wherein the compound is attached to the delivery enhancing transporter by a linker.

45. The method of claim 44, wherein the linker is a releasable linker which releases the compound from the delivery-enhancing transporter after the compound has passed into and through one or more layers of an epithelial or endothelial tissue.

46. The method of claim 45, wherein the compound is biologically active upon release from the linker.

47. The method of claim 31, wherein the compound is substantially inactive when conjugated to the delivery-enhancing transporter.

48. The method of claim 45, wherein the half-life of the conjugate is between 5 minutes and 24 hours upon contact with the epithelial or endothelial tissue.

49. The method of claim 48, wherein half-life of the conjugate is between 30 minutes and 2 hours upon contact with the epithelial or endothelial tissue.

50. The method of claim 45, wherein the compound is released from the linker by solvent-mediated cleavage.

51. The method of claim 44, wherein the conjugate is substantially stable at acidic pH but the compound is substantially released from the delivery-enhancing transporter at physiological pH.

52. The method of claim 31, wherein the conjugate has a structure selected from the group consisting of structures 3, 4, 5 and 6, as follows:

wherein;

R₁—

X comprises the compound;

X is a functional group on the compound to which the remainder of the conjugate is attached;

Y is N or CH;

R₂ is hydrogen, alkyl, aryl, acyl, or allyl;

R₃ comprises the delivery-enhancing transporter;

R₄ is unsubstituted O, substituted N or C or substituted or unsubstituted S;

R₅ is OH, SH or NHR₆;

R₆ is hydrogen, alkyl, aryl, acyl or allyl;

k and m are each independently selected from 1 and 2; and

n is 1 to 10; and

Ar is an aryl group having the attached radicals arranged in an ortho or para configuration, which aryl group can be substituted or unsubstituted.

53. The method of claim 52, wherein X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

54. The method of claim 52, wherein the conjugate comprises structure 3 and R₂ is selected to obtain a conjugate half-life of between 5 minutes and 24 hours.

55. The method of claim 52, wherein the conjugate comprises structure 3, Y is N, and R₂ is methyl, ethyl, propyl, butyl, allyl, benzyl or phenyl.

56. The method of claim 53, wherein R₂ is benzyl;

k, m, and n are each 1, and X is O.

57. The method of claim 52, wherein the conjugate comprises structure 4;

R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

58. The method of claim 52, wherein the conjugate comprises structure 4;

R₅ is NHR₆;

R₆ is hydrogen, methyl, allyl, butyl or phenyl; and

k and m are each 1.

59. The method of claim 52, wherein the conjugate comprises structure 6 and X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

60. The method of claim 52, wherein the conjugate comprises structure 6 and R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

61. A method for enhancing delivery of a compound into and across one or more layers of an animal epithelial or endothelial tissue, the method comprising:

contacting the epithelial or endothelial tissue with a conjugate that comprises the compound and a delivery-enhancing transporter,

wherein the delivery-enhancing transporter comprises sufficient guanidino or amidino moieties to increase delivery of the conjugate into and across one or more intact epithelial or endothelial tissue layers compared to delivery of the compound in the absence of the delivery-enhancing transporter, and

wherein the compound is selected from the group consisting of;

an anti-inflammatory agent,

caffeine,

proline,

salicylic acid,

vitamin E;

a therapeutic agent for treating cystic fibrosis, asthma, allergic rhinitis or chronic obstructive pulmonary disease;

a compound that acts in the gastrointestinal epithelium; and

a compound that acts upon immune cells in the dermis.

62. The method of claim 61, wherein the compound is an anti-inflammatory agent.

63. The method of claim 61, wherein the compound is caffeine, proline, salicylic acid, or vitamin E.

64. The method of claim 61, wherein the compound is a therapeutic agent for treating cystic fibrosis, asthma, allergic rhinitis or chronic obstructive pulmonary disease.

65. The method of claim 61, wherein the compound is a compound that acts in the gastrointestinal epithelium.

66. The method of claim 61, wherein the compound is a compound that acts upon immune cells in the dermis.

67. The method of claim 61, wherein the compound is selected from the group consisting of corticosteroids, NSIADs, cromolyn, and nedocromil.

68. The method of claim 61, wherein the therapeutic agent for treating asthma is selected from the group consisting of an antiinflammatory agent, a bronchodilator, and an immunosuppressive drug.

69. The method of claim 61, wherein the therapeutic agent is an antiinflammatory agent selected from the group consisting of a corticosteroid, cromolyn, and nedocromil.

70. The method of claim 61, wherein the compound is a therapeutic for a condition selected from the group consisting of ulcerative colitis, gastrointestinal ulcers, Crohn'"'"'s disease, peptic ulcer disease, and abnormal proliferative diseases.

71. The method of claim 61, wherein the compound is a therapeutic for ulcers and is selected from the group consisting of an H₂ histamine inhibitor, an inhibitor of the proton-potassium ATPase, and an antibiotic directed at Helicobacter pylori.

72. The method of claim 61, wherein the delivery-enhancing transporter comprises a non-peptide backbone.

73. The method of claim 61, wherein the delivery-enhancing transporter is not attached to an amino acid sequence to which the delivery enhancing transporter molecule is attached in a naturally occurring protein.

74. The method of claim 61, wherein the delivery-enhancing transporter comprises from 5 to 25 guanidino or amidino moieties.

75. The method of claim 74, wherein the delivery-enhancing transporter comprises between 7 and 15 guanidino moieties.

76. The method of claim 61, wherein the delivery-enhancing transporter comprises at least 6 contiguous guanidino and/or amidino moieties.

77. The method of claim 61, wherein the delivery-enhancing transporter consists essentially of 5 to 50 amino acids, at least 50 percent of which amino acids are arginines or analogs thereof.

78. The method of claim 77, wherein the delivery-enhancing transporter comprises 5 to 25 arginine residues or analogs thereof.

79. The method of claim 78, wherein at least one arginine is a D-arginine.

80. The method of claim 79, wherein all of the arginines are D-arginines.

81. The method of claim 77, wherein at least 70 percent of the amino acids that comprise the delivery-enhancing transporter are arginines or arginine analogs.

82. The method of claim 77, wherein the delivery-enhancing transporter comprises at least 5 contiguous arginines or arginine analogs.

83. The method of claim 61, wherein the compound is attached to the delivery enhancing transporter by a linker.

84. The method of claim 83, wherein the linker is a releasable linker which releases the compound from the delivery-enhancing transporter after the compound has passed into and through one or more layers of an epithelial or endothelial tissue.

85. The method of claim 84, wherein the compound is biologically active upon release from the linker.

86. The method of claim 61, wherein the compound is substantially inactive when conjugated to the delivery-enhancing transporter.

87. The method of claim 84, wherein the half-life of the conjugate is between 5 minutes and 24 hours upon contact with the epithelial or endothelial tissue.

88. The method of claim 84, wherein half-life of the conjugate is between 30 minutes and 2 hours upon contact with the epithelial or endothelial tissue.

89. The method of claim 84, wherein the compound is released from the linker by solvent-mediated cleavage.

90. The method of claim 83, wherein the conjugate is substantially stable at acidic pH but the compound is substantially released from the delivery-enhancing transporter at physiological pH.

91. The method of claim 61, wherein the conjugate has a structure selected from the group consisting of structures 3, 4, 5 and 6, as follows:

wherein;

R₁—

X comprises the compound;

X is a functional group on the compound to which the remainder of the conjugate is attached;

Y is N or CH;

R₂ is hydrogen, alkyl, aryl, acyl, or allyl;

R₃ comprises the delivery-enhancing transporter;

R₄ is unsubstituted O, substituted N or C or substituted or unsubstituted S;

R₅ is OH, SH or NHR₆;

R₆ is hydrogen, alkyl, aryl, acyl or allyl;

k and m are each independently selected from 1 and 2; and

n is 1 to 10; and

Ar is an aryl group having the attached radicals arranged in an ortho or para configuration, which aryl group can be substituted or unsubstituted.

92. The method of claim 91, wherein X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

93. The method of claim 91, wherein the conjugate comprises structure 3 and R₂ is selected to obtain a conjugate half-life of between 5 minutes and 24 hours.

94. The method of claim 91, wherein the conjugate comprises structure 3, Y is N, and R₂ is methyl, ethyl, propyl, butyl, allyl, benzyl or phenyl.

95. The method of claim 94, wherein R₂ is benzyl;

k, m, and n are each 1, and X is O.

96. The method of claim 91, wherein the conjugate comprises structure 4;

R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

97. The method of claim 96, wherein the conjugate comprises structure 4;

R₅ is NHR₆;

R₆ is hydrogen, methyl, allyl, butyl or phenyl; and

k and m are each 1.

98. The method of claim 91, wherein the conjugate comprises structure 6 and X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

99. The method of claim 91, wherein the conjugate comprises structure 6 and R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

100. The method of claim 61, wherein delivery of the compound into and across the intact epithelial tissue layers is at least two-fold greater than that of the compound conjugated to a basic HIV tat peptide consisting of residues 49-57.

101. The method of claim 61, wherein the epithelial tissue is the skin.

102. The method of claim 61, wherein the epithelial tissue an eye.

103. The method of claim 61, wherein the epithelial tissue a gastrointestinal epithelium.

104. The method of claim 61, wherein the epithelial tissue a bronchial epithelium.

110. The conjugate of claim 104, wherein R₂ is phenyl;

k, m, and n are each 1, and X is O.

105. A method for enhancing delivery of a compound into and across one or more layers of an animal epithelial or endothelial tissue, the method comprising:

contacting the epithelial or endothelial tissue with a conjugate that comprises the compound and a delivery-enhancing transporter,

wherein the delivery-enhancing transporter comprises sufficient guanidino or amidino moieties to increase delivery of the conjugate into and across one or more intact epithelial or endothelial tissue layers compared to delivery of the compound in the absence of the delivery-enhancing transporter; and

wherein the conjugate is administered topically and the compound is taken up by cells that comprise the follicular or interfollicular epidermis.

106. A conjugate comprising a) a compound to be delivered into and across one or more layers of an animal epithelial or endothelial tissue, and b) a delivery-enhancing transporter that comprises 5 to 25 arginine residues;

wherein the conjugate is substantially stable at acidic pH but the compound is substantially released from the delivery-enhancing transporter at physiological pH.

107. The conjugate of claim 106, wherein the conjugate is selected from the group consisting of structures 3, 4, 5 and 6, as follows:

wherein;

R₁—

X comprises the compound;

X is a functional group on the compound to which the remainder of the conjugate is attached;

Y is N or CH;

R₂ is hydrogen, alkyl, aryl, acyl, or allyl;

R₃ comprises the delivery-enhancing transporter;

R₄ is unsubstituted O, substituted N or C or substituted or unsubstituted S;

R₅ is OH, SH or NHR₆,

R₆ is hydrogen, alkyl, aryl, acyl or allyl;

k and m are each independently selected from 1 and 2; and

n is 1 to 10; and

Ar is an aryl group having the attached radicals arranged in an ortho or para configuration, which aryl group can be substituted or unsubstituted.

108. The conjugate of claim 107, wherein X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

109. The conjugate of claim 107, wherein the conjugate comprises structure 3, Y is N, and R₂ is methyl, ethyl, propyl, butyl, allyl, benzyl or phenyl.

111. The conjugate of claim 107, wherein the linker comprises structure 4;

R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

112. The conjugate of claim 107, wherein the conjugate comprises structure 4;

R₅ is NHR₆;

R₆ is hydrogen, methyl, allyl, butyl or phenyl; and

k and m are each 1.

113. The conjugate of claim 107, wherein the conjugate comprises:

wherein Ph is phenyl.

114. The conjugate of claim 107, wherein the conjugate comprises structure 6 and X is selected from the group consisting of NH, O, S, and CR₇R₈, wherein R₇ and R₈ are each independently selected from the group consisting of H and alkyl.

115. The conjugate of claim 107, wherein the conjugate comprises structure 6 and R₄ is S;

R₅ is NHR₆; and

R₆ is hydrogen, methyl, allyl, butyl or phenyl.

116. The conjugate of claim 107, wherein the conjugate comprises:

117. The conjugate of claim 106, wherein the delivery-enhancing transporter comprises 7 to 15 arginine residues or arginine analogs.

118. The conjugate of claim 106, wherein the delivery-enhancing transporter consists essentially of 5 to 50 amino acids, at least 50 percent of which amino acids are arginines or arginine analogs.

119. The conjugate of claim 106, wherein the delivery-enhancing transporter comprises at least 5 contiguous arginines or arginine analogs.

120. The conjugate of claim 106, wherein the compound is selected from the group consisting of immunosuppressives, antibacterials, antifungals, antivirals, antiproliferatives, hormones, antiinflammatories, vitamins, and analgesics.

121. The conjugate of claim 120, wherein the compound is an immunosuppressive.

122. The conjugate of claim 121, wherein the immunosuppressive is cyclosporin.

123. The conjugate of claim 106, wherein the compound is a glucocorticoid or an ascomycin.

124. A method for delivering a conjugate into and across one or more layers of an animal epithelial or endothelial tissue, the method comprising:

contacting the epithelial or endothelial tissue with a conjugate wherein the conjugate is structure 8;

wherein T is a delivery-enhancing transporter comprising sufficient guanidino or amidino moieties to increase delivery of the conjugate into and across one or more intact epithelial or endothelial tissue layers compared to delivery of the compound in the absence of the delivery-enhancing transporter.

125. The method of claim 124, wherein the delivery-enhancing transporter comprises from 5 to 25 guanidino or amidino moieties.

126. The method of claim 124, wherein the delivery-enhancing transporter comprises between 7 and 15 guanidino moieties.

127. The method of claim 124, wherein the delivery-enhancing transporter comprises at least 6 contiguous guanidino and/or amidino moieties.

128. The method of claim 124, wherein the delivery-enhancing transporter consists essentially of 5 to 50 amino acids, at least 50 percent of which amino acids are arginines or analogs thereof.

129. The method of claim 124, wherein the delivery-enhancing transporter comprises 5 to 25 arginine residues or analogs thereof.

130. The method of claim 129, wherein at least one arginine is a D-arginine.

131. The method of claim 129, wherein all of the arginines are D-arginines.

132. The method of claim 128, wherein at least 70 percent of the amino acids that comprise the delivery-enhancing transporter are arginines or arginine analogs.

133. The method of claim 128, wherein the delivery-enhancing transporter comprises at least 5 contiguous arginines or arginine analogs.

134. The method of claim 126, wherein the compound is a systematically active agent.