gamma-aminobutyric acid gamma-Aminobutyric Acid: The most common inhibitory neurotransmitter in the central nervous system.. gamma-aminobutyric acid : A gamma-amino acid that is butanoic acid with the amino substituent located at C-4. | 1.99 | 1 | 0 | amino acid zwitterion; gamma-amino acid; monocarboxylic acid | human metabolite; neurotransmitter; Saccharomyces cerevisiae metabolite; signalling molecule |
formaldehyde paraform: polymerized formaldehyde; RN given refers to parent cpd; used in root canal therapy | 2 | 1 | 0 | aldehyde; one-carbon compound | allergen; carcinogenic agent; disinfectant; EC 3.5.1.4 (amidase) inhibitor; environmental contaminant; Escherichia coli metabolite; mouse metabolite; Saccharomyces cerevisiae metabolite |
nitrous oxide Nitrous Oxide: Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.. dinitrogen oxide : A nitrogen oxide consisting of linear unsymmetrical molecules with formula N2O. While it is the most used gaseous anaesthetic in the world, its major commercial use, due to its solubility under pressure in vegetable fats combined with its non-toxicity in low concentrations, is as an aerosol spray propellant and aerating agent for canisters of 'whipped' cream. | 1.96 | 1 | 0 | gas molecular entity; nitrogen oxide | analgesic; bacterial metabolite; food packaging gas; food propellant; general anaesthetic; greenhouse gas; inhalation anaesthetic; NMDA receptor antagonist; raising agent; refrigerant; vasodilator agent |
berberine [no description available] | 1.96 | 1 | 0 | alkaloid antibiotic; berberine alkaloid; botanical anti-fungal agent; organic heteropentacyclic compound | antilipemic drug; antineoplastic agent; antioxidant; EC 1.1.1.141 [15-hydroxyprostaglandin dehydrogenase (NAD(+))] inhibitor; EC 1.1.1.21 (aldehyde reductase) inhibitor; EC 1.13.11.52 (indoleamine 2,3-dioxygenase) inhibitor; EC 1.21.3.3 (reticuline oxidase) inhibitor; EC 2.1.1.116 [3'-hydroxy-N-methyl-(S)-coclaurine 4'-O-methyltransferase] inhibitor; EC 2.1.1.122 [(S)-tetrahydroprotoberberine N-methyltransferase] inhibitor; EC 2.7.11.10 (IkappaB kinase) inhibitor; EC 3.1.1.4 (phospholipase A2) inhibitor; EC 3.1.1.7 (acetylcholinesterase) inhibitor; EC 3.1.1.8 (cholinesterase) inhibitor; EC 3.1.3.48 (protein-tyrosine-phosphatase) inhibitor; EC 3.4.14.5 (dipeptidyl-peptidase IV) inhibitor; EC 3.4.21.26 (prolyl oligopeptidase) inhibitor; geroprotector; hypoglycemic agent; metabolite; potassium channel blocker |
diazepam Diazepam: A benzodiazepine with anticonvulsant, anxiolytic, sedative, muscle relaxant, and amnesic properties and a long duration of action. Its actions are mediated by enhancement of GAMMA-AMINOBUTYRIC ACID activity.. diazepam : A 1,4-benzodiazepinone that is 1,3-dihydro-2H-1,4-benzodiazepin-2-one substituted by a chloro group at position 7, a methyl group at position 1 and a phenyl group at position 5. | 1.96 | 1 | 0 | 1,4-benzodiazepinone; organochlorine compound | anticonvulsant; anxiolytic drug; environmental contaminant; sedative; xenobiotic |
fentanyl Fentanyl: A potent narcotic analgesic, abuse of which leads to habituation or addiction. It is primarily a mu-opioid agonist. Fentanyl is also used as an adjunct to general anesthetics, and as an anesthetic for induction and maintenance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1078). fentanyl : A monocarboxylic acid amide resulting from the formal condensation of the aryl amino group of N-phenyl-1-(2-phenylethyl)piperidin-4-amine with propanoic acid. | 3.25 | 6 | 0 | anilide; monocarboxylic acid amide; piperidines | adjuvant; anaesthesia adjuvant; anaesthetic; intravenous anaesthetic; mu-opioid receptor agonist; opioid analgesic |
haloperidol Haloperidol: A phenyl-piperidinyl-butyrophenone that is used primarily to treat SCHIZOPHRENIA and other PSYCHOSES. It is also used in schizoaffective disorder, DELUSIONAL DISORDERS, ballism, and TOURETTE SYNDROME (a drug of choice) and occasionally as adjunctive therapy in INTELLECTUAL DISABILITY and the chorea of HUNTINGTON DISEASE. It is a potent antiemetic and is used in the treatment of intractable HICCUPS. (From AMA Drug Evaluations Annual, 1994, p279). haloperidol : A compound composed of a central piperidine structure with hydroxy and p-chlorophenyl substituents at position 4 and an N-linked p-fluorobutyrophenone moiety. | 2 | 1 | 0 | aromatic ketone; hydroxypiperidine; monochlorobenzenes; organofluorine compound; tertiary alcohol | antidyskinesia agent; antiemetic; dopaminergic antagonist; first generation antipsychotic; serotonergic antagonist |
meperidine Meperidine: A narcotic analgesic that can be used for the relief of most types of moderate to severe pain, including postoperative pain and the pain of labor. Prolonged use may lead to dependence of the morphine type; withdrawal symptoms appear more rapidly than with morphine and are of shorter duration.. pethidine : A piperidinecarboxylate ester that is piperidine which is substituted by a methyl group at position 1 and by phenyl and ethoxycarbonyl groups at position 4. It is an analgesic which is used for the treatment of moderate to severe pain, including postoperative pain and labour pain. | 1.96 | 1 | 0 | ethyl ester; piperidinecarboxylate ester; tertiary amino compound | antispasmodic drug; kappa-opioid receptor agonist; mu-opioid receptor agonist; opioid analgesic |
methadone Methadone: A synthetic opioid that is used as the hydrochloride. It is an opioid analgesic that is primarily a mu-opioid agonist. It has actions and uses similar to those of MORPHINE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1082-3). methadone : A racemate comprising equimolar amounts of dextromethadone and levomethadone. It is a opioid analgesic which is used as a painkiller and as a substitute for heroin in the treatment of heroin addiction.. 6-(dimethylamino)-4,4-diphenylheptan-3-one : A ketone that is heptan-3-one substituted by a dimethylamino group at position 6 and two phenyl groups at position 4. | 4.29 | 4 | 1 | benzenes; diarylmethane; ketone; tertiary amino compound | |
procaine Procaine: A local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1016).. procaine : A benzoate ester, formally the result of esterification of 4-aminobenzoic acid with 2-diethylaminoethanol but formed experimentally by reaction of ethyl 4-aminobenzoate with 2-diethylaminoethanol. | 1.99 | 1 | 0 | benzoate ester; substituted aniline; tertiary amino compound | central nervous system depressant; drug allergen; local anaesthetic; peripheral nervous system drug |
propranolol Propranolol: A widely used non-cardioselective beta-adrenergic antagonist. Propranolol has been used for MYOCARDIAL INFARCTION; ARRHYTHMIA; ANGINA PECTORIS; HYPERTENSION; HYPERTHYROIDISM; MIGRAINE; PHEOCHROMOCYTOMA; and ANXIETY but adverse effects instigate replacement by newer drugs.. propranolol : A propanolamine that is propan-2-ol substituted by a propan-2-ylamino group at position 1 and a naphthalen-1-yloxy group at position 3. | 1.99 | 1 | 0 | naphthalenes; propanolamine; secondary amine | anti-arrhythmia drug; antihypertensive agent; anxiolytic drug; beta-adrenergic antagonist; environmental contaminant; human blood serum metabolite; vasodilator agent; xenobiotic |
spiperone Spiperone: A spiro butyrophenone analog similar to HALOPERIDOL and other related compounds. It has been recommended in the treatment of SCHIZOPHRENIA.. spiperone : An azaspiro compound that is 1,3,8-triazaspiro[4.5]decane which is substituted at positions 1, 4, and 8 by phenyl, oxo, and 4-(p-fluorophenyl)-4-oxobutyl groups, respectively. | 2 | 1 | 0 | aromatic ketone; azaspiro compound; organofluorine compound; piperidines; tertiary amino compound | alpha-adrenergic antagonist; antipsychotic agent; dopaminergic antagonist; psychotropic drug; serotonergic antagonist |
sulpiride Sulpiride: A dopamine D2-receptor antagonist. It has been used therapeutically as an antidepressant, antipsychotic, and as a digestive aid. (From Merck Index, 11th ed). sulpiride : A member of the class of benzamides obtained from formal condensation between the carboxy group of 2-methoxy-5-sulfamoylbenzoic acid and the primary amino group of (1-ethylpyrrolidin-2-yl)methylamine. | 2 | 1 | 0 | benzamides; N-alkylpyrrolidine; sulfonamide | antidepressant; antiemetic; antipsychotic agent; dopaminergic antagonist |
reserpine Reserpine: An alkaloid found in the roots of Rauwolfia serpentina and R. vomitoria. Reserpine inhibits the uptake of norepinephrine into storage vesicles resulting in depletion of catecholamines and serotonin from central and peripheral axon terminals. It has been used as an antihypertensive and an antipsychotic as well as a research tool, but its adverse effects limit its clinical use.. reserpine : An alkaloid found in the roots of Rauwolfia serpentina and R. vomitoria. | 1.98 | 1 | 0 | alkaloid ester; methyl ester; yohimban alkaloid | adrenergic uptake inhibitor; antihypertensive agent; EC 3.4.21.26 (prolyl oligopeptidase) inhibitor; environmental contaminant; first generation antipsychotic; plant metabolite; xenobiotic |
phentolamine Phentolamine: A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and hypertensive emergencies, pheochromocytoma, vasospasm of RAYNAUD DISEASE and frostbite, clonidine withdrawal syndrome, impotence, and peripheral vascular disease.. phentolamine : A substituted aniline that is 3-aminophenol in which the hydrogens of the amino group are replaced by 4-methylphenyl and 4,5-dihydro-1H-imidazol-2-ylmethyl groups respectively. An alpha-adrenergic antagonist, it is used for the treatment of hypertension. | 1.99 | 1 | 0 | imidazoles; phenols; substituted aniline; tertiary amino compound | alpha-adrenergic antagonist; vasodilator agent |
pilocarpine Pilocarpine: A slowly hydrolyzed muscarinic agonist with no nicotinic effects. Pilocarpine is used as a miotic and in the treatment of glaucoma.. (+)-pilocarpine : The (+)-enantiomer of pilocarpine. | 1.96 | 1 | 0 | pilocarpine | antiglaucoma drug |
aspartic acid Aspartic Acid: One of the non-essential amino acids commonly occurring in the L-form. It is found in animals and plants, especially in sugar cane and sugar beets. It may be a neurotransmitter.. aspartic acid : An alpha-amino acid that consists of succinic acid bearing a single alpha-amino substituent. L-aspartic acid : The L-enantiomer of aspartic acid. | 1.99 | 1 | 0 | aspartate family amino acid; aspartic acid; L-alpha-amino acid; proteinogenic amino acid | Escherichia coli metabolite; mouse metabolite; neurotransmitter |
methylene chloride Methylene Chloride: A chlorinated hydrocarbon that has been used as an inhalation anesthetic and acts as a narcotic in high concentrations. Its primary use is as a solvent in manufacturing and food technology.. dichloromethane : A member of the class of chloromethanes that is methane in which two of the hydrogens have been replaced by chlorine. A dense, non-flammible colourless liquid at room temperature (b.p. 40degreeC, d = 1.33) which is immiscible with water, it is widely used as a solvent, a paint stripper, and for the removal of caffeine from coffee and tea. | 1.98 | 1 | 0 | chloromethanes; volatile organic compound | carcinogenic agent; polar aprotic solvent; refrigerant |
diphenhydramine hydrochloride Antitussive Agents: Agents that suppress cough. They act centrally on the medullary cough center. EXPECTORANTS, also used in the treatment of cough, act locally.. diphenhydramine hydrochloride : The hydrochloride salt of diphenhydramine. | 1.98 | 1 | 0 | hydrochloride; organoammonium salt | anti-allergic agent; antiemetic; antiparkinson drug; antipruritic drug; H1-receptor antagonist; local anaesthetic; muscarinic antagonist; sedative |
etorphine Etorphine: A narcotic analgesic morphinan used as a sedative in veterinary practice. | 9.3 | 59 | 3 | | |
glutamic acid Glutamic Acid: A non-essential amino acid naturally occurring in the L-form. Glutamic acid is the most common excitatory neurotransmitter in the CENTRAL NERVOUS SYSTEM.. glutamic acid : An alpha-amino acid that is glutaric acid bearing a single amino substituent at position 2. | 1.99 | 1 | 0 | glutamic acid; glutamine family amino acid; L-alpha-amino acid; proteinogenic amino acid | Escherichia coli metabolite; ferroptosis inducer; micronutrient; mouse metabolite; neurotransmitter; nutraceutical |
tramadol Tramadol: A narcotic analgesic proposed for severe pain. It may be habituating.. tramadol : A racemate consisting of equal amounts of (R,R)- and (S,S)-tramadol. A centrally acting synthetic opioid analgesic, used (as the hydrochloride salt) to treat moderately severe pain. The (R,R)-enantiomer exhibits ten-fold higher analgesic potency than the (S,S)-enantiomer. Originally developed by Gruenenthal GmbH and launched in 1977, it was subsequently isolated from the root bark of the South African tree Nauclea latifolia.. (R,R)-tramadol : A 2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol in which both stereocentres have R-configuration; the (R,R)-enantiomer of the racemic opioid analgesic tramadol, it exhibits ten-fold higher analgesic potency than the (S,S)-enantiomer. | 3.79 | 2 | 1 | 2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol | adrenergic uptake inhibitor; antitussive; capsaicin receptor antagonist; delta-opioid receptor agonist; kappa-opioid receptor agonist; metabolite; mu-opioid receptor agonist; muscarinic antagonist; nicotinic antagonist; NMDA receptor antagonist; opioid analgesic; serotonergic antagonist; serotonin uptake inhibitor |
colforsin Colforsin: Potent activator of the adenylate cyclase system and the biosynthesis of cyclic AMP. From the plant COLEUS FORSKOHLII. Has antihypertensive, positive inotropic, platelet aggregation inhibitory, and smooth muscle relaxant activities; also lowers intraocular pressure and promotes release of hormones from the pituitary gland. | 2.42 | 2 | 0 | acetate ester; cyclic ketone; labdane diterpenoid; organic heterotricyclic compound; tertiary alpha-hydroxy ketone; triol | adenylate cyclase agonist; anti-HIV agent; antihypertensive agent; plant metabolite; platelet aggregation inhibitor; protein kinase A agonist |
f 7302 F 7302: structure given in first source | 2.05 | 1 | 0 | piperidines | |
enpiperate enpiperate: RN given refers to parent cpd | 1.96 | 1 | 0 | | |
1-(heptafluorobutyryl)imidazole [no description available] | 1.98 | 1 | 0 | | |
4-(alpha-(4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl)-n,n-diethylbenzamide 4-(alpha-(4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl)-N,N-diethylbenzamide: a highly-selective, nonpeptide delta opioid receptor agonist; structure given in first source | 2 | 1 | 0 | diarylmethane | |
atropine tropan-3alpha-yl 3-hydroxy-2-phenylpropanoate : A tropane alkaloid that is (1R,5)-8-methyl-8-azabicyclo[3.2.1]octane substituted by a (3-hydroxy-2-phenylpropanoyl)oxy group at position 3. | 1.96 | 1 | 0 | | |
diprenorphine Diprenorphine: A narcotic antagonist similar in action to NALOXONE. It is used to remobilize animals after ETORPHINE neuroleptanalgesia and is considered a specific antagonist to etorphine. | 2.39 | 2 | 0 | morphinane alkaloid | |
buprenorphine Buprenorphine: A derivative of the opioid alkaloid THEBAINE that is a more potent and longer lasting analgesic than MORPHINE. It appears to act as a partial agonist at mu and kappa opioid receptors and as an antagonist at delta receptors. The lack of delta-agonist activity has been suggested to account for the observation that buprenorphine tolerance may not develop with chronic use.. buprenorphine : A morphinane alkaloid that is 7,8-dihydromorphine 6-O-methyl ether in which positions 6 and 14 are joined by a -CH2CH2- bridge, one of the hydrogens of the N-methyl group is substituted by cyclopropyl, and a hydrogen at position 7 is substituted by a 2-hydroxy-3,3-dimethylbutan-2-yl group. It is highly effective for the treatment of opioid use disorder and is also increasingly being used in the treatment of chronic pain. | 4.35 | 6 | 0 | morphinane alkaloid | delta-opioid receptor antagonist; kappa-opioid receptor antagonist; mu-opioid receptor agonist; opioid analgesic |
tetrahydropalmatine [no description available] | 1.96 | 1 | 0 | | |
hydromorphone Hydromorphone: An opioid analgesic made from MORPHINE and used mainly as an analgesic. It has a shorter duration of action than morphine.. hydromorphone : A morphinane alkaloid that is a hydrogenated ketone derivative of morphine. A semi-synthetic drug, it is a centrally acting pain medication of the opioid class. | 3.11 | 1 | 0 | morphinane alkaloid; organic heteropentacyclic compound | mu-opioid receptor agonist; opioid analgesic |
nalorphine Nalorphine: A narcotic antagonist with some agonist properties. It is an antagonist at mu opioid receptors and an agonist at kappa opioid receptors. Given alone it produces a broad spectrum of unpleasant effects and it is considered to be clinically obsolete. | 1.96 | 1 | 0 | morphinane alkaloid | |
naloxone Naloxone: A specific opiate antagonist that has no agonist activity. It is a competitive antagonist at mu, delta, and kappa opioid receptors.. naloxone : A synthetic morphinane alkaloid that is morphinone in which the enone double bond has been reduced to a single bond, the hydrogen at position 14 has been replaced by a hydroxy group, and the methyl group attached to the nitrogen has been replaced by an allyl group. A specific opioid antagonist, it is used (commonly as its hydrochloride salt) to reverse the effects of opioids, both following their use of opioids during surgery and in cases of known or suspected opioid overdose. | 3.7 | 10 | 0 | morphinane alkaloid; organic heteropentacyclic compound; tertiary alcohol | antidote to opioid poisoning; central nervous system depressant; mu-opioid receptor antagonist |
morphine Meconium: The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the INTESTINAL GLANDS; BILE PIGMENTS; FATTY ACIDS; AMNIOTIC FLUID; and intrauterine debris. It constitutes the first stools passed by a newborn. | 4.07 | 15 | 0 | morphinane alkaloid; organic heteropentacyclic compound; tertiary amino compound | anaesthetic; drug allergen; environmental contaminant; geroprotector; mu-opioid receptor agonist; opioid analgesic; plant metabolite; vasodilator agent; xenobiotic |
beta-funaltrexamine beta-funaltrexamine: RN given refers to parent cpd(E)-isomer; structure given in first source | 2.39 | 2 | 0 | morphinane alkaloid | |
thebaine Thebaine: A drug that is derived from opium, which contains from 0.3-1.5% thebaine depending on its origin. It produces strychnine-like convulsions rather than narcosis. It may be habit-forming and is a controlled substance (opiate) listed in the U.S. Code of Federal Regulations, Title 21 Part 1308.12 (1985). (From Merck Index, 11th ed) | 2.4 | 2 | 0 | morphinane alkaloid; organic heteropentacyclic compound | |
naltrexone Naltrexone: Derivative of noroxymorphone that is the N-cyclopropylmethyl congener of NALOXONE. It is a narcotic antagonist that is effective orally, longer lasting and more potent than naloxone, and has been proposed for the treatment of heroin addiction. The FDA has approved naltrexone for the treatment of alcohol dependence.. naltrexone : An organic heteropentacyclic compound that is naloxone substituted in which the allyl group attached to the nitrogen is replaced by a cyclopropylmethyl group. A mu-opioid receptor antagonist, it is used to treat alcohol dependence. | 2.9 | 4 | 0 | cyclopropanes; morphinane-like compound; organic heteropentacyclic compound | antidote to opioid poisoning; central nervous system depressant; environmental contaminant; mu-opioid receptor antagonist; xenobiotic |
oripavine oripavine: from, Papaver orientale L. & P. bacterium Lindl; structure in Merck Index, 9th ed, #6707; RN given refers to (5alpha)-isomer. oripavine : A morphinane alkaloid with formula C18H19NO3. It is the major metabolite of thebaine. | 2.4 | 2 | 0 | ether; morphinane alkaloid; organic heteropentacyclic compound; organic hydroxy compound; tertiary amino compound | bacterial xenobiotic metabolite; opioid analgesic |
heroin Heroin: A narcotic analgesic that may be habit-forming. It is a controlled substance (opium derivative) listed in the U.S. Code of Federal Regulations, Title 21 Parts 329.1, 1308.11 (1987). Sale is forbidden in the United States by Federal statute. (Merck Index, 11th ed). heroin : A morphinane alkaloid that is morphine bearing two acetyl substituents on the O-3 and O-6 positions. As with other opioids, heroin is used as both an analgesic and a recreational drug. Frequent and regular administration is associated with tolerance and physical dependence, which may develop into addiction. Its use includes treatment for acute pain, such as in severe physical trauma, myocardial infarction, post-surgical pain, and chronic pain, including end-stage cancer and other terminal illnesses. | 3.25 | 6 | 0 | morphinane alkaloid | mu-opioid receptor agonist; opioid analgesic; prodrug |
6-o-monoacetylmorphine 6-O-monoacetylmorphine: RN given refers to parent cpd(5alpha,6alpha)-isomer | 1.99 | 1 | 0 | morphinane alkaloid | |
norbinaltorphimine norbinaltorphimine: kappa opiate receptor antagonist; structure given in first source | 2.39 | 2 | 0 | isoquinolines | |
binaltorphimine binaltorphimine: kappa opiate receptor antagonist; structure given in first source | 1.98 | 1 | 0 | | |
enkephalin, ala(2)-mephe(4)-gly(5)- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-: An enkephalin analog that selectively binds to the MU OPIOID RECEPTOR. It is used as a model for drug permeability experiments. | 2 | 1 | 0 | | |
naltrindole naltrindole: delta opioid receptor antagonist | 2.39 | 2 | 0 | isoquinolines | |
morphinans Morphinans: Compounds based on a partially saturated iminoethanophenanthrene, which can be described as ethylimino-bridged benzo-decahydronaphthalenes. They include some of the OPIOIDS found in PAPAVER that are used as ANALGESICS. | 4.57 | 8 | 0 | isoquinoline alkaloid fundamental parent; morphinane alkaloid | |
enkephalin, leucine-2-alanine Enkephalin, Leucine-2-Alanine: A delta-selective opioid (ANALGESICS, OPIOID). It can cause transient depression of mean arterial blood pressure and heart rate. | 1.98 | 1 | 0 | | |
stepholidine stepholidine: protoberberine alkaloid isolated from opium; dual D1 receptor agonist and D2 receptor antagonist | 1.96 | 1 | 0 | | |
naloxonazine naloxonazine: binds irreversibly to opiate receptor sites; structure given in first source | 1.98 | 1 | 0 | | |
piperidines Piperidines: A family of hexahydropyridines. | 1.96 | 1 | 0 | | |
guanosine 5'-o-(3-thiotriphosphate) Guanosine 5'-O-(3-Thiotriphosphate): Guanosine 5'-(trihydrogen diphosphate), monoanhydride with phosphorothioic acid. A stable GTP analog which enjoys a variety of physiological actions such as stimulation of guanine nucleotide-binding proteins, phosphoinositide hydrolysis, cyclic AMP accumulation, and activation of specific proto-oncogenes. | 2.93 | 4 | 0 | nucleoside triphosphate analogue | |